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Index: head/share/man/man9/Makefile
===================================================================
--- head/share/man/man9/Makefile
+++ head/share/man/man9/Makefile
@@ -1570,7 +1570,6 @@
timeout.9 callout_active.9 \
timeout.9 callout_deactivate.9 \
timeout.9 callout_drain.9 \
- timeout.9 callout_drain_async.9 \
timeout.9 callout_handle_init.9 \
timeout.9 callout_init.9 \
timeout.9 callout_init_mtx.9 \
Index: head/share/man/man9/timeout.9
===================================================================
--- head/share/man/man9/timeout.9
+++ head/share/man/man9/timeout.9
@@ -29,14 +29,13 @@
.\"
.\" $FreeBSD$
.\"
-.Dd January 14, 2015
+.Dd October 8, 2014
.Dt TIMEOUT 9
.Os
.Sh NAME
.Nm callout_active ,
.Nm callout_deactivate ,
.Nm callout_drain ,
-.Nm callout_drain_async ,
.Nm callout_handle_init ,
.Nm callout_init ,
.Nm callout_init_mtx ,
@@ -64,232 +63,279 @@
.In sys/systm.h
.Bd -literal
typedef void timeout_t (void *);
-typedef void callout_func_t (void *);
.Ed
+.Ft int
+.Fn callout_active "struct callout *c"
+.Ft void
+.Fn callout_deactivate "struct callout *c"
+.Ft int
+.Fn callout_drain "struct callout *c"
+.Ft void
+.Fn callout_handle_init "struct callout_handle *handle"
+.Bd -literal
+struct callout_handle handle = CALLOUT_HANDLE_INITIALIZER(&handle);
+.Ed
+.Ft void
+.Fn callout_init "struct callout *c" "int mpsafe"
+.Ft void
+.Fn callout_init_mtx "struct callout *c" "struct mtx *mtx" "int flags"
+.Ft void
+.Fn callout_init_rm "struct callout *c" "struct rmlock *rm" "int flags"
+.Ft void
+.Fn callout_init_rw "struct callout *c" "struct rwlock *rw" "int flags"
+.Ft int
+.Fn callout_pending "struct callout *c"
+.Ft int
+.Fn callout_reset "struct callout *c" "int ticks" "timeout_t *func" "void *arg"
+.Ft int
+.Fn callout_reset_curcpu "struct callout *c" "int ticks" "timeout_t *func" \
+"void *arg"
+.Ft int
+.Fn callout_reset_on "struct callout *c" "int ticks" "timeout_t *func" \
+"void *arg" "int cpu"
+.Ft int
+.Fn callout_reset_sbt "struct callout *c" "sbintime_t sbt" \
+"sbintime_t pr" "timeout_t *func" "void *arg" "int flags"
+.Ft int
+.Fn callout_reset_sbt_curcpu "struct callout *c" "sbintime_t sbt" \
+"sbintime_t pr" "timeout_t *func" "void *arg" "int flags"
+.Ft int
+.Fn callout_reset_sbt_on "struct callout *c" "sbintime_t sbt" \
+"sbintime_t pr" "timeout_t *func" "void *arg" "int cpu" "int flags"
+.Ft int
+.Fn callout_schedule "struct callout *c" "int ticks"
+.Ft int
+.Fn callout_schedule_curcpu "struct callout *c" "int ticks"
+.Ft int
+.Fn callout_schedule_on "struct callout *c" "int ticks" "int cpu"
+.Ft int
+.Fn callout_schedule_sbt "struct callout *c" "sbintime_t sbt" \
+"sbintime_t pr" "int flags"
+.Ft int
+.Fn callout_schedule_sbt_curcpu "struct callout *c" "sbintime_t sbt" \
+"sbintime_t pr" "int flags"
+.Ft int
+.Fn callout_schedule_sbt_on "struct callout *c" "sbintime_t sbt" \
+"sbintime_t pr" "int cpu" "int flags"
+.Ft int
+.Fn callout_stop "struct callout *c"
+.Ft struct callout_handle
+.Fn timeout "timeout_t *func" "void *arg" "int ticks"
+.Ft void
+.Fn untimeout "timeout_t *func" "void *arg" "struct callout_handle handle"
.Sh DESCRIPTION
The
.Nm callout
API is used to schedule a call to an arbitrary function at a specific
-time in the future in a single-shot fashion.
-Consumers of this API are required to allocate a
-.Pq struct callout
-structure for each pending function invocation.
-The
+time in the future.
+Consumers of this API are required to allocate a callout structure
.Pq struct callout
-structure stores the full state about any pending function call and
-should be drained by a call to
-.Fn callout_drain
-or
-.Fn callout_drain_async
-before freeing.
-.Sh INITIALISATION
-.Ft void
-.Fn callout_handle_init "struct callout_handle *handle"
-This function is deprecated and is used to prepare a
-.Pq struct callout_handle
-structure before it can be used the first time.
-If this function is called on a pending timeout, the pending timeout
-cannot be cancelled and the
-.Fn untimeout
-function will return as if there was no timeout pending.
+for each pending function invocation.
+This structure stores state about the pending function invocation including
+the function to be called and the time at which the function should be invoked.
+Pending function calls can be cancelled or rescheduled to a different time.
+In addition,
+a callout structure may be reused to schedule a new function call after a
+scheduled call is completed.
+.Pp
+Callouts only provide a single-shot mode.
+If a consumer requires a periodic timer,
+it must explicitly reschedule each function call.
+This is normally done by rescheduling the subsequent call within the called
+function.
.Pp
-.Fn CALLOUT_HANDLE_INITIALIZER "&handle"
-This macro is deprecated and can be used instead of
-.Fn callout_handle_init
-to assign the default state to the
-.Pq struct callout_handle
-structure when declaring static timeouts.
+Callout functions must not sleep.
+They may not acquire sleepable locks,
+wait on condition variables,
+perform blocking allocation requests,
+or invoke any other action that might sleep.
.Pp
-.Ft void
-.Fn callout_init "struct callout *c" "int mpsafe"
-This function prepares a
-.Pq struct callout
-structure before it can be used.
-This function should not be used when the callout is pending a timeout.
+Each callout structure must be initialized by
+.Fn callout_init ,
+.Fn callout_init_mtx ,
+.Fn callout_init_rm ,
+or
+.Fn callout_init_rw
+before it is passed to any of the other callout functions.
+The
+.Fn callout_init
+function initializes a callout structure in
+.Fa c
+that is not associated with a specific lock.
If the
.Fa mpsafe
-argument is non-zero, the callback function will be running unlocked.
-Else the Giant mutex will be locked before calling the callback function.
+argument is zero,
+the callout structure is not considered to be
+.Dq multi-processor safe ;
+and the Giant lock will be acquired before calling the callout function
+and released when the callout function returns.
.Pp
-.Ft void
-.Fn callout_init_mtx "struct callout *c" "struct mtx *mtx" "int flags"
-This function prepares a
-.Pq struct callout
-structure before it can be used.
-This function should not be used when the callout is pending a timeout.
The
-.Fa mtx
-argument should be non-zero and should specify a pointer to a valid
-spinlock type of mutex or a valid regular non-sleepable mutex which
-the callback subsystem should lock before calling the callback
-function.
-Valid
+.Fn callout_init_mtx ,
+.Fn callout_init_rm ,
+and
+.Fn callout_init_rw
+functions initialize a callout structure in
+.Fa c
+that is associated with a specific lock.
+The lock is specified by the
+.Fa mtx ,
+.Fa rm ,
+or
+.Fa rw
+parameter.
+The associated lock must be held while stopping or rescheduling the
+callout.
+The callout subsystem acquires the associated lock before calling the
+callout function and releases it after the function returns.
+If the callout was cancelled while the callout subsystem waited for the
+associated lock,
+the callout function is not called,
+and the associated lock is released.
+This ensures that stopping or rescheduling the callout will abort any
+previously scheduled invocation.
+.Pp
+Only regular mutexes may be used with
+.Fn callout_init_mtx ;
+spin mutexes are not supported.
+A sleepable read-mostly lock
+.Po
+one initialized with the
+.Dv RM_SLEEPABLE
+flag
+.Pc
+may not be used with
+.Fn callout_init_rm .
+Similarly, other sleepable lock types such as
+.Xr sx 9
+and
+.Xr lockmgr 9
+cannot be used with callouts because sleeping is not permitted in
+the callout subsystem.
+.Pp
+These
.Fa flags
-are:
+may be specified for
+.Fn callout_init_mtx ,
+.Fn callout_init_rm ,
+or
+.Fn callout_init_rw :
.Bl -tag -width ".Dv CALLOUT_RETURNUNLOCKED"
.It Dv CALLOUT_RETURNUNLOCKED
-It is assumed that the callout function has released the specified
-mutex before returning.
-Else the callout subsystem will release the specified mutex after the
-callout function has returned.
+The callout function will release the associated lock itself,
+so the callout subsystem should not attempt to unlock it
+after the callout function returns.
+.It Dv CALLOUT_SHAREDLOCK
+The lock is only acquired in read mode when running the callout handler.
+This flag is ignored by
+.Fn callout_init_mtx .
.El
.Pp
-.Ft void
-.Fn callout_init_rm "struct callout *c" "struct rmlock *rm" "int flags"
-This function is the same like the
-.Fn callout_init_mtx
-function except it accepts a read-mostly type of lock.
-The read-mostly lock must not be initialised with the
-.Dv RM_SLEEPABLE
-flag.
+The function
+.Fn callout_stop
+cancels a callout
+.Fa c
+if it is currently pending.
+If the callout is pending, then
+.Fn callout_stop
+returns a non-zero value.
+If the callout is not set,
+has already been serviced,
+or is currently being serviced,
+then zero will be returned.
+If the callout has an associated lock,
+then that lock must be held when this function is called.
.Pp
-.Ft void
-.Fn callout_init_rw "struct callout *c" "struct rwlock *rw" "int flags"
-This function is the same like the
-.Fn callout_init_mtx
-function except it accepts a reader-writer type of lock.
-.Sh SCHEDULING CALLOUTS
-.Ft struct callout_handle
-.Fn timeout "timeout_t *func" "void *arg" "int ticks"
-This function is deprecated and schedules a call to the function given by the argument
-.Fa func
-to take place after
+The function
+.Fn callout_drain
+is identical to
+.Fn callout_stop
+except that it will wait for the callout
+.Fa c
+to complete if it is already in progress.
+This function MUST NOT be called while holding any
+locks on which the callout might block, or deadlock will result.
+Note that if the callout subsystem has already begun processing this
+callout, then the callout function may be invoked before
+.Fn callout_drain
+returns.
+However, the callout subsystem does guarantee that the callout will be
+fully stopped before
+.Fn callout_drain
+returns.
+.Pp
+The
+.Fn callout_reset
+and
+.Fn callout_schedule
+function families schedule a future function invocation for callout
+.Fa c .
+If
+.Fa c
+already has a pending callout,
+it is cancelled before the new invocation is scheduled.
+These functions return a non-zero value if a pending callout was cancelled
+and zero if there was no pending callout.
+If the callout has an associated lock,
+then that lock must be held when any of these functions are called.
+.Pp
+The time at which the callout function will be invoked is determined by
+either the
+.Fa ticks
+argument or the
+.Fa sbt ,
+.Fa pr ,
+and
+.Fa flags
+arguments.
+When
+.Fa ticks
+is used,
+the callout is scheduled to execute after
.Fa ticks Ns No /hz
seconds.
Non-positive values of
.Fa ticks
are silently converted to the value
.Sq 1 .
-The
-.Fa func
-argument should be a valid pointer to a function that takes a single
-.Fa void *
-argument.
-Upon invocation, the
-.Fa func
-function will receive
-.Fa arg
-as its only argument.
-The Giant lock is locked when the
-.Fa arg
-function is invoked and should not be unlocked by this function.
-The returned value from
-.Fn timeout
-is a
-.Ft struct callout_handle
-structure which can be used in conjunction with the
-.Fn untimeout
-function to request that a scheduled timeout be cancelled.
-As handles are recycled by the system, it is possible, although unlikely,
-that a handle from one invocation of
-.Fn timeout
-may match the handle of another invocation of
-.Fn timeout
-if both calls used the same function pointer and argument, and the first
-timeout is expired or canceled before the second call.
-Please ensure that the function and argument pointers are unique when using this function.
.Pp
-.Ft int
-.Fn callout_reset "struct callout *c" "int ticks" "callout_func_t *func" "void *arg"
-This function is used to schedule or re-schedule a callout.
-This function at first stops the callout given by the
-.Fa c
-argument, if any.
-Then it will start the callout given by the
-.Fa c
-argument.
-The relative time until the timeout callback happens is given by the
-.Fa ticks
-argument.
-The number of ticks in a second is defined by
-.Dv hz
-and can vary from system to system.
-This function returns a non-zero value if the given callout was pending and
-the callback function was prevented from being called.
-Else a value of zero is returned.
-If a lock is associated with the callout given by the
-.Fa c
-argument and it is exclusivly locked when this function is called this
-function will always ensure that previous callback function, if any,
-is never reached.
-In other words the callout will be atomically restarted.
-Else there is no such guarantee.
-The callback function is given by the
-.Fa func
-argument and its function argument is given by the
-.Fa arg
-argument.
-.Pp
-.Ft int
-.Fn callout_reset_curcpu "struct callout *c" "int ticks" "callout_func_t *func" \
-"void *arg"
-This function works the same like the
-.Fn callout_reset
-function except the callback function given by the
-.Fa func
-argument will be executed on the same CPU which called this function.
-A change in the CPU selection can happen if the callout has a lock
-associated with it and is locked when this function is called.
-A change in the CPU selection cannot happen if this function is
-re-scheduled inside a callout function.
-Else the callback function given by the
-.Fa func
-argument will be executed on the same CPU like previously done.
-.Pp
-.Ft int
-.Fn callout_reset_on "struct callout *c" "int ticks" "callout_func_t *func" \
-"void *arg" "int cpu"
-This function works the same like the
-.Fn callout_reset
-function except the callback function given by the
-.Fa func
-argument will be executed on the CPU given by the
-.Fa cpu
-argument.
-A change in the CPU selection can happen if the callout has a lock
-associated with it and is locked when this function is called.
-A change in the CPU selection cannot happen if this function is
-re-scheduled inside a callout function.
-Else the callback function given by the
-.Fa func
-argument will be executed on the same CPU like previously done.
-.Pp
-.Ft int
-.Fn callout_reset_sbt "struct callout *c" "sbintime_t sbt" \
-"sbintime_t pr" "callout_func_t *func" "void *arg" "int flags"
-This function works the same like the
-.Fn callout_reset
-function except the relative or absolute time after which the timeout
-callback should happen is given by the
+The
+.Fa sbt ,
+.Fa pr ,
+and
+.Fa flags
+arguments provide more control over the scheduled time including
+support for higher resolution times,
+specifying the precision of the scheduled time,
+and setting an absolute deadline instead of a relative timeout.
+The callout is scheduled to execute in a time window which begins at
+the time specified in
.Fa sbt
-argument and extends for the amount of time specified in the
-.Fa pr
-argument.
-This function is used when you need high precision timeouts.
-If the
+and extends for the amount of time specified in
+.Fa pr .
+If
.Fa sbt
-argument specifies a time in the past,
+specifies a time in the past,
the window is adjusted to start at the current time.
A non-zero value for
.Fa pr
allows the callout subsystem to coalesce callouts scheduled close to each
other into fewer timer interrupts,
reducing processing overhead and power consumption.
-The
+These
.Fa flags
-argument may be non-zero to adjust the interpretation of the
+may be specified to adjust the interpretation of
.Fa sbt
-and the
-.Fa pr
-arguments:
+and
+.Fa pr :
.Bl -tag -width ".Dv C_DIRECT_EXEC"
.It Dv C_ABSOLUTE
Handle the
.Fa sbt
argument as an absolute time since boot.
-By default, the
+By default,
.Fa sbt
-argument is treated like a relative amount of time,
+is treated as a relative amount of time,
similar to
.Fa ticks .
.It Dv C_DIRECT_EXEC
@@ -301,7 +347,7 @@
and should be as small as possible because they run with absolute priority.
.It Fn C_PREL
Specifies relative event time precision as binary logarithm of time interval
-divided by acceptable time deviation: 1 -- 1/2, 2 -- 1/4 and so on.
+divided by acceptable time deviation: 1 -- 1/2, 2 -- 1/4, etc.
Note that the larger of
.Fa pr
or this value is used as the length of the time window.
@@ -314,215 +360,65 @@
calls if possible.
.El
.Pp
-.Ft int
-.Fn callout_reset_sbt_curcpu "struct callout *c" "sbintime_t sbt" \
-"sbintime_t pr" "callout_func_t *func" "void *arg" "int flags"
-This function works the same like the
-.Fn callout_reset_sbt
-function except the callback function given by the
-.Fa func
-argument will be executed on the same CPU which called this function.
-A change in the CPU selection can happen if the callout has a lock
-associated with it and is locked when this function is called.
-A change in the CPU selection cannot happen if this function is
-re-scheduled inside a callout function.
-Else the callback function given by the
-.Fa func
-argument will be executed on the same CPU like previously done.
-.Pp
-.Ft int
-.Fn callout_reset_sbt_on "struct callout *c" "sbintime_t sbt" \
-"sbintime_t pr" "callout_func_t *func" "void *arg" "int cpu" "int flags"
-This function works the same like the
-.Fn callout_reset_sbt
-function except the callback function given by the
+The
+.Fn callout_reset
+functions accept a
.Fa func
-argument will be executed on the CPU given by the
-.Fa cpu
+argument which identifies the function to be called when the time expires.
+It must be a pointer to a function that takes a single
+.Fa void *
argument.
-A change in the CPU selection can happen if the callout has a lock
-associated with it and is locked when this function is called.
-A change in the CPU selection cannot happen if this function is
-re-scheduled inside a callout function.
-Else the callback function given by the
+Upon invocation,
.Fa func
-argument will be executed on the same CPU like previously done.
-.Pp
-.Ft int
-.Fn callout_schedule "struct callout *c" "int ticks"
-This function works the same like the
-.Fn callout_reset
-function except it re-uses the callback function and the callback argument
-already stored in the
-.Pq struct callout
-structure.
-.Pp
-.Ft int
-.Fn callout_schedule_curcpu "struct callout *c" "int ticks"
-This function works the same like the
-.Fn callout_reset_curcpu
-function except it re-uses the callback function and the callback argument
-already stored in the
-.Pq struct callout
-structure.
-.Pp
-.Ft int
-.Fn callout_schedule_on "struct callout *c" "int ticks" "int cpu"
-This function works the same like the
-.Fn callout_reset_on
-function except it re-uses the callback function and the callback argument
-already stored in the
-.Pq struct callout
-structure.
-.Pp
-.Ft int
-.Fn callout_schedule_sbt "struct callout *c" "sbintime_t sbt" \
-"sbintime_t pr" "int flags"
-This function works the same like the
-.Fn callout_reset_sbt
-function except it re-uses the callback function and the callback argument
-already stored in the
-.Pq struct callout
-structure.
-.Pp
-.Ft int
-.Fn callout_schedule_sbt_curcpu "struct callout *c" "sbintime_t sbt" \
-"sbintime_t pr" "int flags"
-This function works the same like the
-.Fn callout_reset_sbt_curcpu
-function except it re-uses the callback function and the callback argument
-already stored in the
-.Pq struct callout
-structure.
-.Pp
-.Ft int
-.Fn callout_schedule_sbt_on "struct callout *c" "sbintime_t sbt" \
-"sbintime_t pr" "int cpu" "int flags"
-This function works the same like the
-.Fn callout_reset_sbt_on
-function except it re-uses the callback function and the callback argument
-already stored in the
-.Pq struct callout
-structure.
-.Sh CHECKING THE STATE OF CALLOUTS
-.Ft int
-.Fn callout_pending "struct callout *c"
-This function returns non-zero if the callout pointed to by the
-.Fa c
-argument is pending for callback.
-Else this function returns zero.
-This function returns zero when inside the callout function if the
-callout is not re-scheduled.
-.Pp
-.Ft int
-.Fn callout_active "struct callout *c"
-This function is deprecated and returns non-zero if the callout
-pointed to by the
-.Fa c
-argument was scheduled in the past.
-Else this function returns zero.
-This function also returns zero after the
-.Fn callout_deactivate
-or the
-.Fn callout_stop
-or the
-.Fn callout_drain
-or the
-.Fn callout_drain_async
-function is called on the same callout as given by the
-.Fa c
-argument.
-.Pp
-.Ft void
-.Fn callout_deactivate "struct callout *c"
-This function is deprecated and ensures that subsequent calls to the
-.Fn callout_activate
-function returns zero until the callout is scheduled again.
-.Sh STOPPING CALLOUTS
-.Ft void
-.Fn untimeout "timeout_t *func" "void *arg" "struct callout_handle handle"
-This function is deprecated and cancels the timeout associated with the
-.Fa handle
-argument using the function pointed to by the
+will receive
+.Fa arg
+as its only argument.
+The
+.Fn callout_schedule
+functions reuse the
.Fa func
-argument and having the
+and
.Fa arg
-arguments to validate the handle.
-If the handle does not correspond to a timeout with
-the function
+arguments from the previous callout.
+Note that one of the
+.Fn callout_reset
+functions must always be called to initialize
.Fa func
-taking the argument
+and
.Fa arg
-no action is taken. The
-.Fa handle
-must be initialised by a previous call to
-.Fn timeout ,
-.Fn callout_handle_init
-or assigned the value of
-.Fn CALLOUT_HANDLE_INITIALIZER "&handle"
-before being passed to
-.Fn untimeout .
-The behavior of calling
-.Fn untimeout
-with an uninitialised handle
-is undefined.
+before one of the
+.Fn callout_schedule
+functions can be used.
.Pp
-.Ft int
-.Fn callout_stop "struct callout *c"
-This function is used to stop a timeout function invocation associated with the callout pointed to by the
-.Fa c
-argument, in a non-blocking fashion.
-This function can be called multiple times in a row with no side effects, even if the callout is already stopped. This function however should not be called before the callout has been initialised.
-This function returns a non-zero value if the given callout was pending and
-the callback function was prevented from being called.
-Else a value of zero is returned.
-If a lock is associated with the callout given by the
-.Fa c
-argument and it is exclusivly locked when this function is called, the
-.Fn callout_stop
-function will always ensure that the callback function is never reached.
-In other words the callout will be atomically stopped.
-Else there is no such guarantee.
-.Sh DRAINING CALLOUTS
-.Ft int
-.Fn callout_drain "struct callout *c"
-This function works the same like the
-.Fn callout_stop
-function except it ensures that all callback functions have returned and there are no more references to the callout pointed to by the
-.Fa c
-argument inside the callout subsystem before it returns.
-Also this function ensures that the lock, if any, associated with the
-callout is no longer being used.
-When this function returns, it is safe to free the callout structure pointed to by the
-.Fa c
-argument.
+The callout subsystem provides a softclock thread for each CPU in the system.
+Callouts are assigned to a single CPU and are executed by the softclock thread
+for that CPU.
+Initially,
+callouts are assigned to CPU 0.
+The
+.Fn callout_reset_on ,
+.Fn callout_reset_sbt_on ,
+.Fn callout_schedule_on
+and
+.Fn callout_schedule_sbt_on
+functions assign the callout to CPU
+.Fa cpu .
+The
+.Fn callout_reset_curcpu ,
+.Fn callout_reset_sbt_curpu ,
+.Fn callout_schedule_curcpu
+and
+.Fn callout_schedule_sbt_curcpu
+functions assign the callout to the current CPU.
+The
+.Fn callout_reset ,
+.Fn callout_reset_sbt ,
+.Fn callout_schedule
+and
+.Fn callout_schedule_sbt
+functions schedule the callout to execute in the softclock thread of the CPU
+to which it is currently assigned.
.Pp
-.Ft int
-.Fn callout_drain_async "struct callout *c" "callout_func_t *fn" "void *arg"
-This function is non-blocking and works the same like the
-.Fn callout_stop
-function except if it returns non-zero it means the callback function pointed to by the
-.Fa fn
-argument will be called back with the
-.Fa arg
-argument when all references to the callout pointed to by the
-.Fa c
-argument are gone.
-If this function returns zero, it is safe to free the callout structure pointed to by the
-.Fa c
-argument right away.
-.Sh CALLOUT FUNCTION RESTRICTIONS
-Callout functions must not sleep.
-They may not acquire sleepable locks, wait on condition variables,
-perform blocking allocation requests, or invoke any other action that
-might sleep.
-.Sh CALLOUT SUBSYSTEM INTERNALS
-The callout subsystem has its own set of spinlocks to protect its internal state.
-The callout subsystem provides a softclock thread for each CPU in the
-system.
-Callouts are assigned to a single CPU and are executed by the
-softclock thread for that CPU.
-Initially, callouts are assigned to CPU 0.
Softclock threads are not pinned to their respective CPUs by default.
The softclock thread for CPU 0 can be pinned to CPU 0 by setting the
.Va kern.pin_default_swi
@@ -531,7 +427,50 @@
respective CPUs by setting the
.Va kern.pin_pcpu_swi
loader tunable to a non-zero value.
-.Sh "AVOIDING RACE CONDITIONS"
+.Pp
+The macros
+.Fn callout_pending ,
+.Fn callout_active
+and
+.Fn callout_deactivate
+provide access to the current state of the callout.
+The
+.Fn callout_pending
+macro checks whether a callout is
+.Em pending ;
+a callout is considered
+.Em pending
+when a timeout has been set but the time has not yet arrived.
+Note that once the timeout time arrives and the callout subsystem
+starts to process this callout,
+.Fn callout_pending
+will return
+.Dv FALSE
+even though the callout function may not have finished
+.Pq or even begun
+executing.
+The
+.Fn callout_active
+macro checks whether a callout is marked as
+.Em active ,
+and the
+.Fn callout_deactivate
+macro clears the callout's
+.Em active
+flag.
+The callout subsystem marks a callout as
+.Em active
+when a timeout is set and it clears the
+.Em active
+flag in
+.Fn callout_stop
+and
+.Fn callout_drain ,
+but it
+.Em does not
+clear it when a callout expires normally via the execution of the
+callout function.
+.Ss "Avoiding Race Conditions"
The callout subsystem invokes callout functions from its own thread
context.
Without some kind of synchronization,
@@ -548,7 +487,7 @@
The first approach is preferred as it is the simplest:
.Bl -enum -offset indent
.It
-Callouts can be associated with a specific lock when they are initialised
+Callouts can be associated with a specific lock when they are initialized
by
.Fn callout_init_mtx ,
.Fn callout_init_rm ,
@@ -569,7 +508,7 @@
.Fn callout_schedule
functions to provide this safety.
.Pp
-A callout initialised via
+A callout initialized via
.Fn callout_init
with
.Fa mpsafe
@@ -592,8 +531,9 @@
.Pc
indicates whether or not the callout was removed.
If it is known that the callout was set and the callout function has
-not yet executed, then a return value of zero indicates that the
-callout function is about to be called.
+not yet executed, then a return value of
+.Dv FALSE
+indicates that the callout function is about to be called.
For example:
.Bd -literal -offset indent
if (sc->sc_flags & SCFLG_CALLOUT_RUNNING) {
@@ -649,14 +589,16 @@
.Em pending
flag and return without action if
.Fn callout_pending
-returns non-zero.
+returns
+.Dv TRUE .
This indicates that the callout was rescheduled using
.Fn callout_reset
just before the callout function was invoked.
If
.Fn callout_active
-returns zero then the callout function should also return without
-action.
+returns
+.Dv FALSE
+then the callout function should also return without action.
This indicates that the callout has been stopped.
Finally, the callout function should call
.Fn callout_deactivate
@@ -726,13 +668,129 @@
or releasing the storage for the callout structure.
.Sh LEGACY API
.Bf Sy
-The
+The functions below are a legacy API that will be removed in a future release.
+New code should not use these routines.
+.Ef
+.Pp
+The function
+.Fn timeout
+schedules a call to the function given by the argument
+.Fa func
+to take place after
+.Fa ticks Ns No /hz
+seconds.
+Non-positive values of
+.Fa ticks
+are silently converted to the value
+.Sq 1 .
+.Fa func
+should be a pointer to a function that takes a
+.Fa void *
+argument.
+Upon invocation,
+.Fa func
+will receive
+.Fa arg
+as its only argument.
+The return value from
.Fn timeout
+is a
+.Ft struct callout_handle
+which can be used in conjunction with the
+.Fn untimeout
+function to request that a scheduled timeout be canceled.
+.Pp
+The function
+.Fn callout_handle_init
+can be used to initialize a handle to a state which will cause
+any calls to
+.Fn untimeout
+with that handle to return with no side
+effects.
+.Pp
+Assigning a callout handle the value of
+.Fn CALLOUT_HANDLE_INITIALIZER
+performs the same function as
+.Fn callout_handle_init
+and is provided for use on statically declared or global callout handles.
+.Pp
+The function
+.Fn untimeout
+cancels the timeout associated with
+.Fa handle
+using the
+.Fa func
and
+.Fa arg
+arguments to validate the handle.
+If the handle does not correspond to a timeout with
+the function
+.Fa func
+taking the argument
+.Fa arg
+no action is taken.
+.Fa handle
+must be initialized by a previous call to
+.Fn timeout ,
+.Fn callout_handle_init ,
+or assigned the value of
+.Fn CALLOUT_HANDLE_INITIALIZER "&handle"
+before being passed to
+.Fn untimeout .
+The behavior of calling
.Fn untimeout
-functions are a legacy API that will be removed in a future release.
-New code should not use these routines.
-.Ef
+with an uninitialized handle
+is undefined.
+.Pp
+As handles are recycled by the system, it is possible (although unlikely)
+that a handle from one invocation of
+.Fn timeout
+may match the handle of another invocation of
+.Fn timeout
+if both calls used the same function pointer and argument, and the first
+timeout is expired or canceled before the second call.
+The timeout facility offers O(1) running time for
+.Fn timeout
+and
+.Fn untimeout .
+Timeouts are executed from
+.Fn softclock
+with the
+.Va Giant
+lock held.
+Thus they are protected from re-entrancy.
+.Sh RETURN VALUES
+The
+.Fn callout_active
+macro returns the state of a callout's
+.Em active
+flag.
+.Pp
+The
+.Fn callout_pending
+macro returns the state of a callout's
+.Em pending
+flag.
+.Pp
+The
+.Fn callout_reset
+and
+.Fn callout_schedule
+function families return non-zero if the callout was pending before the new
+function invocation was scheduled.
+.Pp
+The
+.Fn callout_stop
+and
+.Fn callout_drain
+functions return non-zero if the callout was still pending when it was
+called or zero otherwise.
+The
+.Fn timeout
+function returns a
+.Ft struct callout_handle
+that can be passed to
+.Fn untimeout .
.Sh HISTORY
The current timeout and untimeout routines are based on the work of
.An Adam M. Costello
@@ -757,4 +815,4 @@
.Bx
linked list
callout mechanism which offered O(n) insertion and removal running time
-and did not generate or require handles for untimeout operations.
+but did not generate or require handles for untimeout operations.
Index: head/sys/kern/init_main.c
===================================================================
--- head/sys/kern/init_main.c
+++ head/sys/kern/init_main.c
@@ -504,8 +504,7 @@
callout_init_mtx(&p->p_itcallout, &p->p_mtx, 0);
callout_init_mtx(&p->p_limco, &p->p_mtx, 0);
- mtx_init(&td->td_slpmutex, "td_slpmutex", NULL, MTX_SPIN);
- callout_init_mtx(&td->td_slpcallout, &td->td_slpmutex, 0);
+ callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
/* Create credentials. */
p->p_ucred = crget();
Index: head/sys/kern/kern_condvar.c
===================================================================
--- head/sys/kern/kern_condvar.c
+++ head/sys/kern/kern_condvar.c
@@ -313,13 +313,15 @@
DROP_GIANT();
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
- sleepq_release(cvp);
sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
if (lock != &Giant.lock_object) {
+ if (class->lc_flags & LC_SLEEPABLE)
+ sleepq_release(cvp);
WITNESS_SAVE(lock, lock_witness);
lock_state = class->lc_unlock(lock);
+ if (class->lc_flags & LC_SLEEPABLE)
+ sleepq_lock(cvp);
}
- sleepq_lock(cvp);
rval = sleepq_timedwait(cvp, 0);
#ifdef KTRACE
@@ -381,13 +383,15 @@
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
SLEEPQ_INTERRUPTIBLE, 0);
- sleepq_release(cvp);
sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
if (lock != &Giant.lock_object) {
+ if (class->lc_flags & LC_SLEEPABLE)
+ sleepq_release(cvp);
WITNESS_SAVE(lock, lock_witness);
lock_state = class->lc_unlock(lock);
+ if (class->lc_flags & LC_SLEEPABLE)
+ sleepq_lock(cvp);
}
- sleepq_lock(cvp);
rval = sleepq_timedwait_sig(cvp, 0);
#ifdef KTRACE
Index: head/sys/kern/kern_lock.c
===================================================================
--- head/sys/kern/kern_lock.c
+++ head/sys/kern/kern_lock.c
@@ -210,11 +210,9 @@
GIANT_SAVE();
sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
SLEEPQ_INTERRUPTIBLE : 0), queue);
- if ((flags & LK_TIMELOCK) && timo) {
- sleepq_release(&lk->lock_object);
+ if ((flags & LK_TIMELOCK) && timo)
sleepq_set_timeout(&lk->lock_object, timo);
- sleepq_lock(&lk->lock_object);
- }
+
/*
* Decisional switch for real sleeping.
*/
Index: head/sys/kern/kern_switch.c
===================================================================
--- head/sys/kern/kern_switch.c
+++ head/sys/kern/kern_switch.c
@@ -93,6 +93,8 @@
&DPCPU_NAME(sched_switch_stats[SWT_TURNSTILE]), "");
SCHED_STAT_DEFINE_VAR(sleepq,
&DPCPU_NAME(sched_switch_stats[SWT_SLEEPQ]), "");
+SCHED_STAT_DEFINE_VAR(sleepqtimo,
+ &DPCPU_NAME(sched_switch_stats[SWT_SLEEPQTIMO]), "");
SCHED_STAT_DEFINE_VAR(relinquish,
&DPCPU_NAME(sched_switch_stats[SWT_RELINQUISH]), "");
SCHED_STAT_DEFINE_VAR(needresched,
Index: head/sys/kern/kern_synch.c
===================================================================
--- head/sys/kern/kern_synch.c
+++ head/sys/kern/kern_synch.c
@@ -236,16 +236,12 @@
* return from cursig().
*/
sleepq_add(ident, lock, wmesg, sleepq_flags, 0);
+ if (sbt != 0)
+ sleepq_set_timeout_sbt(ident, sbt, pr, flags);
if (lock != NULL && class->lc_flags & LC_SLEEPABLE) {
sleepq_release(ident);
WITNESS_SAVE(lock, lock_witness);
lock_state = class->lc_unlock(lock);
- if (sbt != 0)
- sleepq_set_timeout_sbt(ident, sbt, pr, flags);
- sleepq_lock(ident);
- } else if (sbt != 0) {
- sleepq_release(ident);
- sleepq_set_timeout_sbt(ident, sbt, pr, flags);
sleepq_lock(ident);
}
if (sbt != 0 && catch)
@@ -310,11 +306,8 @@
* We put ourselves on the sleep queue and start our timeout.
*/
sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0);
- if (sbt != 0) {
- sleepq_release(ident);
+ if (sbt != 0)
sleepq_set_timeout_sbt(ident, sbt, pr, flags);
- sleepq_lock(ident);
- }
/*
* Can't call ktrace with any spin locks held so it can lock the
Index: head/sys/kern/kern_thread.c
===================================================================
--- head/sys/kern/kern_thread.c
+++ head/sys/kern/kern_thread.c
@@ -149,9 +149,6 @@
audit_thread_alloc(td);
#endif
umtx_thread_alloc(td);
-
- mtx_init(&td->td_slpmutex, "td_slpmutex", NULL, MTX_SPIN);
- callout_init_mtx(&td->td_slpcallout, &td->td_slpmutex, 0);
return (0);
}
@@ -165,10 +162,6 @@
td = (struct thread *)mem;
- /* make sure to drain any use of the "td->td_slpcallout" */
- callout_drain(&td->td_slpcallout);
- mtx_destroy(&td->td_slpmutex);
-
#ifdef INVARIANTS
/* Verify that this thread is in a safe state to free. */
switch (td->td_state) {
@@ -551,6 +544,7 @@
LIST_INIT(&td->td_lprof[0]);
LIST_INIT(&td->td_lprof[1]);
sigqueue_init(&td->td_sigqueue, p);
+ callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
p->p_numthreads++;
}
Index: head/sys/kern/kern_timeout.c
===================================================================
--- head/sys/kern/kern_timeout.c
+++ head/sys/kern/kern_timeout.c
@@ -54,8 +54,6 @@
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
-#include <sys/rmlock.h>
-#include <sys/rwlock.h>
#include <sys/proc.h>
#include <sys/sdt.h>
#include <sys/sleepqueue.h>
@@ -126,216 +124,37 @@
*/
u_int callwheelsize, callwheelmask;
-typedef void callout_mutex_op_t(struct lock_object *);
-typedef int callout_owned_op_t(struct lock_object *);
-
-struct callout_mutex_ops {
- callout_mutex_op_t *lock;
- callout_mutex_op_t *unlock;
- callout_owned_op_t *owned;
-};
-
-enum {
- CALLOUT_LC_UNUSED_0,
- CALLOUT_LC_UNUSED_1,
- CALLOUT_LC_UNUSED_2,
- CALLOUT_LC_UNUSED_3,
- CALLOUT_LC_SPIN,
- CALLOUT_LC_MUTEX,
- CALLOUT_LC_RW,
- CALLOUT_LC_RM,
-};
-
-static void
-callout_mutex_op_none(struct lock_object *lock)
-{
-}
-
-static int
-callout_owned_op_none(struct lock_object *lock)
-{
- return (0);
-}
-
-static void
-callout_mutex_lock(struct lock_object *lock)
-{
- mtx_lock((struct mtx *)lock);
-}
-
-static void
-callout_mutex_unlock(struct lock_object *lock)
-{
- mtx_unlock((struct mtx *)lock);
-}
-
-static void
-callout_mutex_lock_spin(struct lock_object *lock)
-{
- mtx_lock_spin((struct mtx *)lock);
-}
-
-static void
-callout_mutex_unlock_spin(struct lock_object *lock)
-{
- mtx_unlock_spin((struct mtx *)lock);
-}
-
-static int
-callout_mutex_owned(struct lock_object *lock)
-{
- return (mtx_owned((struct mtx *)lock));
-}
-
-static void
-callout_rm_wlock(struct lock_object *lock)
-{
- rm_wlock((struct rmlock *)lock);
-}
-
-static void
-callout_rm_wunlock(struct lock_object *lock)
-{
- rm_wunlock((struct rmlock *)lock);
-}
-
-static int
-callout_rm_owned(struct lock_object *lock)
-{
- return (rm_wowned((struct rmlock *)lock));
-}
-
-static void
-callout_rw_wlock(struct lock_object *lock)
-{
- rw_wlock((struct rwlock *)lock);
-}
-
-static void
-callout_rw_wunlock(struct lock_object *lock)
-{
- rw_wunlock((struct rwlock *)lock);
-}
-
-static int
-callout_rw_owned(struct lock_object *lock)
-{
- return (rw_wowned((struct rwlock *)lock));
-}
-
-static const struct callout_mutex_ops callout_mutex_ops[8] = {
- [CALLOUT_LC_UNUSED_0] = {
- .lock = callout_mutex_op_none,
- .unlock = callout_mutex_op_none,
- .owned = callout_owned_op_none,
- },
- [CALLOUT_LC_UNUSED_1] = {
- .lock = callout_mutex_op_none,
- .unlock = callout_mutex_op_none,
- .owned = callout_owned_op_none,
- },
- [CALLOUT_LC_UNUSED_2] = {
- .lock = callout_mutex_op_none,
- .unlock = callout_mutex_op_none,
- .owned = callout_owned_op_none,
- },
- [CALLOUT_LC_UNUSED_3] = {
- .lock = callout_mutex_op_none,
- .unlock = callout_mutex_op_none,
- .owned = callout_owned_op_none,
- },
- [CALLOUT_LC_SPIN] = {
- .lock = callout_mutex_lock_spin,
- .unlock = callout_mutex_unlock_spin,
- .owned = callout_mutex_owned,
- },
- [CALLOUT_LC_MUTEX] = {
- .lock = callout_mutex_lock,
- .unlock = callout_mutex_unlock,
- .owned = callout_mutex_owned,
- },
- [CALLOUT_LC_RW] = {
- .lock = callout_rw_wlock,
- .unlock = callout_rw_wunlock,
- .owned = callout_rw_owned,
- },
- [CALLOUT_LC_RM] = {
- .lock = callout_rm_wlock,
- .unlock = callout_rm_wunlock,
- .owned = callout_rm_owned,
- },
-};
-
-static void
-callout_lock_client(int c_flags, struct lock_object *c_lock)
-{
- callout_mutex_ops[CALLOUT_GET_LC(c_flags)].lock(c_lock);
-}
-
-static void
-callout_unlock_client(int c_flags, struct lock_object *c_lock)
-{
- callout_mutex_ops[CALLOUT_GET_LC(c_flags)].unlock(c_lock);
-}
-
-#ifdef SMP
-static int
-callout_lock_owned_client(int c_flags, struct lock_object *c_lock)
-{
- return (callout_mutex_ops[CALLOUT_GET_LC(c_flags)].owned(c_lock));
-}
-#endif
-
/*
- * The callout CPU exec structure represent information necessary for
- * describing the state of callouts currently running on the CPU and
- * for handling deferred callout restarts.
- *
- * In particular, the first entry of the array cc_exec_entity holds
- * information for callouts running from the SWI thread context, while
- * the second one holds information for callouts running directly from
- * the hardware interrupt context.
+ * The callout cpu exec entities represent informations necessary for
+ * describing the state of callouts currently running on the CPU and the ones
+ * necessary for migrating callouts to the new callout cpu. In particular,
+ * the first entry of the array cc_exec_entity holds informations for callout
+ * running in SWI thread context, while the second one holds informations
+ * for callout running directly from hardware interrupt context.
+ * The cached informations are very important for deferring migration when
+ * the migrating callout is already running.
*/
struct cc_exec {
- /*
- * The "cc_curr" points to the currently executing callout and
- * is protected by the "cc_lock" spinlock. If no callback is
- * currently executing it is equal to "NULL".
- */
+ struct callout *cc_next;
struct callout *cc_curr;
- /*
- * The "cc_restart_args" structure holds the argument for a
- * deferred callback restart and is protected by the "cc_lock"
- * spinlock. The structure is only valid if "cc_restart" is
- * "true". If "cc_restart" is "false" the information in the
- * "cc_restart_args" structure shall be ignored.
- */
- struct callout_args cc_restart_args;
- bool cc_restart;
- /*
- * The "cc_cancel" variable allows the currently pending
- * callback to be atomically cancelled. This field is write
- * protected by the "cc_lock" spinlock.
- */
- bool cc_cancel;
- /*
- * The "cc_drain_fn" points to a function which shall be
- * called with the argument stored in "cc_drain_arg" when an
- * asynchronous drain is performed. This field is write
- * protected by the "cc_lock" spinlock.
- */
- callout_func_t *cc_drain_fn;
- void *cc_drain_arg;
+#ifdef SMP
+ void (*ce_migration_func)(void *);
+ void *ce_migration_arg;
+ int ce_migration_cpu;
+ sbintime_t ce_migration_time;
+ sbintime_t ce_migration_prec;
+#endif
+ bool cc_cancel;
+ bool cc_waiting;
};
/*
- * There is one "struct callout_cpu" per CPU, holding all relevant
+ * There is one struct callout_cpu per cpu, holding all relevant
* state for the callout processing thread on the individual CPU.
*/
struct callout_cpu {
struct mtx_padalign cc_lock;
struct cc_exec cc_exec_entity[2];
- struct callout *cc_exec_next_dir;
struct callout *cc_callout;
struct callout_list *cc_callwheel;
struct callout_tailq cc_expireq;
@@ -347,7 +166,27 @@
char cc_ktr_event_name[20];
};
+#define cc_exec_curr cc_exec_entity[0].cc_curr
+#define cc_exec_next cc_exec_entity[0].cc_next
+#define cc_exec_cancel cc_exec_entity[0].cc_cancel
+#define cc_exec_waiting cc_exec_entity[0].cc_waiting
+#define cc_exec_curr_dir cc_exec_entity[1].cc_curr
+#define cc_exec_next_dir cc_exec_entity[1].cc_next
+#define cc_exec_cancel_dir cc_exec_entity[1].cc_cancel
+#define cc_exec_waiting_dir cc_exec_entity[1].cc_waiting
+
#ifdef SMP
+#define cc_migration_func cc_exec_entity[0].ce_migration_func
+#define cc_migration_arg cc_exec_entity[0].ce_migration_arg
+#define cc_migration_cpu cc_exec_entity[0].ce_migration_cpu
+#define cc_migration_time cc_exec_entity[0].ce_migration_time
+#define cc_migration_prec cc_exec_entity[0].ce_migration_prec
+#define cc_migration_func_dir cc_exec_entity[1].ce_migration_func
+#define cc_migration_arg_dir cc_exec_entity[1].ce_migration_arg
+#define cc_migration_cpu_dir cc_exec_entity[1].ce_migration_cpu
+#define cc_migration_time_dir cc_exec_entity[1].ce_migration_time
+#define cc_migration_prec_dir cc_exec_entity[1].ce_migration_prec
+
struct callout_cpu cc_cpu[MAXCPU];
#define CPUBLOCK MAXCPU
#define CC_CPU(cpu) (&cc_cpu[(cpu)])
@@ -372,9 +211,60 @@
static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");
+/**
+ * Locked by cc_lock:
+ * cc_curr - If a callout is in progress, it is cc_curr.
+ * If cc_curr is non-NULL, threads waiting in
+ * callout_drain() will be woken up as soon as the
+ * relevant callout completes.
+ * cc_cancel - Changing to 1 with both callout_lock and cc_lock held
+ * guarantees that the current callout will not run.
+ * The softclock() function sets this to 0 before it
+ * drops callout_lock to acquire c_lock, and it calls
+ * the handler only if curr_cancelled is still 0 after
+ * cc_lock is successfully acquired.
+ * cc_waiting - If a thread is waiting in callout_drain(), then
+ * callout_wait is nonzero. Set only when
+ * cc_curr is non-NULL.
+ */
+
+/*
+ * Resets the execution entity tied to a specific callout cpu.
+ */
+static void
+cc_cce_cleanup(struct callout_cpu *cc, int direct)
+{
+
+ cc->cc_exec_entity[direct].cc_curr = NULL;
+ cc->cc_exec_entity[direct].cc_next = NULL;
+ cc->cc_exec_entity[direct].cc_cancel = false;
+ cc->cc_exec_entity[direct].cc_waiting = false;
+#ifdef SMP
+ cc->cc_exec_entity[direct].ce_migration_cpu = CPUBLOCK;
+ cc->cc_exec_entity[direct].ce_migration_time = 0;
+ cc->cc_exec_entity[direct].ce_migration_prec = 0;
+ cc->cc_exec_entity[direct].ce_migration_func = NULL;
+ cc->cc_exec_entity[direct].ce_migration_arg = NULL;
+#endif
+}
+
+/*
+ * Checks if migration is requested by a specific callout cpu.
+ */
+static int
+cc_cce_migrating(struct callout_cpu *cc, int direct)
+{
+
+#ifdef SMP
+ return (cc->cc_exec_entity[direct].ce_migration_cpu != CPUBLOCK);
+#else
+ return (0);
+#endif
+}
+
/*
- * Kernel low level callwheel initialization called from cpu0 during
- * kernel startup:
+ * Kernel low level callwheel initialization
+ * called on cpu0 during kernel startup.
*/
static void
callout_callwheel_init(void *dummy)
@@ -434,6 +324,8 @@
LIST_INIT(&cc->cc_callwheel[i]);
TAILQ_INIT(&cc->cc_expireq);
cc->cc_firstevent = SBT_MAX;
+ for (i = 0; i < 2; i++)
+ cc_cce_cleanup(cc, i);
snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name),
"callwheel cpu %d", cpu);
if (cc->cc_callout == NULL) /* Only cpu0 handles timeout(9) */
@@ -441,11 +333,41 @@
for (i = 0; i < ncallout; i++) {
c = &cc->cc_callout[i];
callout_init(c, 0);
- c->c_flags |= CALLOUT_LOCAL_ALLOC;
+ c->c_flags = CALLOUT_LOCAL_ALLOC;
SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
}
}
+#ifdef SMP
+/*
+ * Switches the cpu tied to a specific callout.
+ * The function expects a locked incoming callout cpu and returns with
+ * locked outcoming callout cpu.
+ */
+static struct callout_cpu *
+callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu)
+{
+ struct callout_cpu *new_cc;
+
+ MPASS(c != NULL && cc != NULL);
+ CC_LOCK_ASSERT(cc);
+
+ /*
+ * Avoid interrupts and preemption firing after the callout cpu
+ * is blocked in order to avoid deadlocks as the new thread
+ * may be willing to acquire the callout cpu lock.
+ */
+ c->c_cpu = CPUBLOCK;
+ spinlock_enter();
+ CC_UNLOCK(cc);
+ new_cc = CC_CPU(new_cpu);
+ CC_LOCK(new_cc);
+ spinlock_exit();
+ c->c_cpu = new_cpu;
+ return (new_cc);
+}
+#endif
+
/*
* Start standard softclock thread.
*/
@@ -522,8 +444,9 @@
#ifdef CALLOUT_PROFILING
int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0;
#endif
+
cc = CC_SELF();
- CC_LOCK(cc);
+ mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
/* Compute the buckets of the last scan and present times. */
firstb = callout_hash(cc->cc_lastscan);
@@ -626,7 +549,7 @@
avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8;
avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8;
#endif
- CC_UNLOCK(cc);
+ mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
/*
* swi_sched acquires the thread lock, so we don't want to call it
* with cc_lock held; incorrect locking order.
@@ -639,55 +562,49 @@
callout_lock(struct callout *c)
{
struct callout_cpu *cc;
- cc = CC_CPU(c->c_cpu);
- CC_LOCK(cc);
+ int cpu;
+
+ for (;;) {
+ cpu = c->c_cpu;
+#ifdef SMP
+ if (cpu == CPUBLOCK) {
+ while (c->c_cpu == CPUBLOCK)
+ cpu_spinwait();
+ continue;
+ }
+#endif
+ cc = CC_CPU(cpu);
+ CC_LOCK(cc);
+ if (cpu == c->c_cpu)
+ break;
+ CC_UNLOCK(cc);
+ }
return (cc);
}
-static struct callout_cpu *
-callout_cc_add_locked(struct callout *c, struct callout_cpu *cc,
- struct callout_args *coa, bool can_swap_cpu)
+static void
+callout_cc_add(struct callout *c, struct callout_cpu *cc,
+ sbintime_t sbt, sbintime_t precision, void (*func)(void *),
+ void *arg, int cpu, int flags)
{
-#ifndef NO_EVENTTIMERS
- sbintime_t sbt;
-#endif
int bucket;
CC_LOCK_ASSERT(cc);
-
- /* update flags before swapping locks, if any */
- c->c_flags &= ~(CALLOUT_PROCESSED | CALLOUT_DIRECT | CALLOUT_DEFRESTART);
- if (coa->flags & C_DIRECT_EXEC)
- c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING | CALLOUT_DIRECT);
- else
- c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
-
-#ifdef SMP
- /*
- * Check if we are changing the CPU on which the callback
- * should be executed and if we have a lock protecting us:
- */
- if (can_swap_cpu != false && coa->cpu != c->c_cpu &&
- callout_lock_owned_client(c->c_flags, c->c_lock) != 0) {
- CC_UNLOCK(cc);
- c->c_cpu = coa->cpu;
- cc = callout_lock(c);
- }
-#endif
- if (coa->time < cc->cc_lastscan)
- coa->time = cc->cc_lastscan;
- c->c_arg = coa->arg;
- c->c_func = coa->func;
- c->c_time = coa->time;
- c->c_precision = coa->precision;
-
+ if (sbt < cc->cc_lastscan)
+ sbt = cc->cc_lastscan;
+ c->c_arg = arg;
+ c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
+ if (flags & C_DIRECT_EXEC)
+ c->c_flags |= CALLOUT_DIRECT;
+ c->c_flags &= ~CALLOUT_PROCESSED;
+ c->c_func = func;
+ c->c_time = sbt;
+ c->c_precision = precision;
bucket = callout_get_bucket(c->c_time);
CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x",
c, (int)(c->c_precision >> 32),
(u_int)(c->c_precision & 0xffffffff));
LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le);
-
- /* Ensure we are first to be scanned, if called via a callback */
if (cc->cc_bucket == bucket)
cc->cc_exec_next_dir = c;
#ifndef NO_EVENTTIMERS
@@ -700,16 +617,17 @@
sbt = c->c_time + c->c_precision;
if (sbt < cc->cc_firstevent) {
cc->cc_firstevent = sbt;
- cpu_new_callout(coa->cpu, sbt, c->c_time);
+ cpu_new_callout(cpu, sbt, c->c_time);
}
#endif
- return (cc);
}
static void
callout_cc_del(struct callout *c, struct callout_cpu *cc)
{
+ if ((c->c_flags & CALLOUT_LOCAL_ALLOC) == 0)
+ return;
c->c_func = NULL;
SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
}
@@ -721,10 +639,20 @@
#endif
int direct)
{
- callout_func_t *c_func;
+ struct rm_priotracker tracker;
+ void (*c_func)(void *);
void *c_arg;
+ struct lock_class *class;
struct lock_object *c_lock;
+ uintptr_t lock_status;
int c_flags;
+#ifdef SMP
+ struct callout_cpu *new_cc;
+ void (*new_func)(void *);
+ void *new_arg;
+ int flags, new_cpu;
+ sbintime_t new_prec, new_time;
+#endif
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
sbintime_t sbt1, sbt2;
struct timespec ts2;
@@ -735,39 +663,37 @@
KASSERT((c->c_flags & (CALLOUT_PENDING | CALLOUT_ACTIVE)) ==
(CALLOUT_PENDING | CALLOUT_ACTIVE),
("softclock_call_cc: pend|act %p %x", c, c->c_flags));
+ class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
+ lock_status = 0;
+ if (c->c_flags & CALLOUT_SHAREDLOCK) {
+ if (class == &lock_class_rm)
+ lock_status = (uintptr_t)&tracker;
+ else
+ lock_status = 1;
+ }
c_lock = c->c_lock;
c_func = c->c_func;
c_arg = c->c_arg;
c_flags = c->c_flags;
-
- /* remove pending bit */
- c->c_flags &= ~CALLOUT_PENDING;
-
- /* reset our local state */
+ if (c->c_flags & CALLOUT_LOCAL_ALLOC)
+ c->c_flags = CALLOUT_LOCAL_ALLOC;
+ else
+ c->c_flags &= ~CALLOUT_PENDING;
cc->cc_exec_entity[direct].cc_curr = c;
- cc->cc_exec_entity[direct].cc_restart = false;
- cc->cc_exec_entity[direct].cc_drain_fn = NULL;
- cc->cc_exec_entity[direct].cc_drain_arg = NULL;
-
+ cc->cc_exec_entity[direct].cc_cancel = false;
+ CC_UNLOCK(cc);
if (c_lock != NULL) {
- cc->cc_exec_entity[direct].cc_cancel = false;
- CC_UNLOCK(cc);
-
- /* unlocked region for switching locks */
-
- callout_lock_client(c_flags, c_lock);
-
+ class->lc_lock(c_lock, lock_status);
/*
- * Check if the callout may have been cancelled while
- * we were switching locks. Even though the callout is
- * specifying a lock, it might not be certain this
- * lock is locked when starting and stopping callouts.
+ * The callout may have been cancelled
+ * while we switched locks.
*/
- CC_LOCK(cc);
if (cc->cc_exec_entity[direct].cc_cancel) {
- callout_unlock_client(c_flags, c_lock);
- goto skip_cc_locked;
+ class->lc_unlock(c_lock);
+ goto skip;
}
+ /* The callout cannot be stopped now. */
+ cc->cc_exec_entity[direct].cc_cancel = true;
if (c_lock == &Giant.lock_object) {
#ifdef CALLOUT_PROFILING
(*gcalls)++;
@@ -788,11 +714,6 @@
CTR3(KTR_CALLOUT, "callout %p func %p arg %p",
c, c_func, c_arg);
}
- /* The callout cannot be stopped now! */
- cc->cc_exec_entity[direct].cc_cancel = true;
- CC_UNLOCK(cc);
-
- /* unlocked region */
KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running",
"func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct);
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
@@ -819,40 +740,85 @@
#endif
KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle");
CTR1(KTR_CALLOUT, "callout %p finished", c);
-
- /*
- * At this point the callback structure might have been freed,
- * so we need to check the previously copied value of
- * "c->c_flags":
- */
if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0)
- callout_unlock_client(c_flags, c_lock);
-
+ class->lc_unlock(c_lock);
+skip:
CC_LOCK(cc);
-
-skip_cc_locked:
KASSERT(cc->cc_exec_entity[direct].cc_curr == c, ("mishandled cc_curr"));
cc->cc_exec_entity[direct].cc_curr = NULL;
-
- /* Check if there is anything which needs draining */
- if (cc->cc_exec_entity[direct].cc_drain_fn != NULL) {
+ if (cc->cc_exec_entity[direct].cc_waiting) {
/*
- * Unlock the CPU callout last, so that any use of
- * structures belonging to the callout are complete:
+ * There is someone waiting for the
+ * callout to complete.
+ * If the callout was scheduled for
+ * migration just cancel it.
*/
+ if (cc_cce_migrating(cc, direct)) {
+ cc_cce_cleanup(cc, direct);
+
+ /*
+ * It should be assert here that the callout is not
+ * destroyed but that is not easy.
+ */
+ c->c_flags &= ~CALLOUT_DFRMIGRATION;
+ }
+ cc->cc_exec_entity[direct].cc_waiting = false;
CC_UNLOCK(cc);
- /* call drain function unlocked */
- cc->cc_exec_entity[direct].cc_drain_fn(
- cc->cc_exec_entity[direct].cc_drain_arg);
+ wakeup(&cc->cc_exec_entity[direct].cc_waiting);
CC_LOCK(cc);
- } else if (c_flags & CALLOUT_LOCAL_ALLOC) {
- /* return callout back to freelist */
- callout_cc_del(c, cc);
- } else if (cc->cc_exec_entity[direct].cc_restart) {
- /* [re-]schedule callout, if any */
- cc = callout_cc_add_locked(c, cc,
- &cc->cc_exec_entity[direct].cc_restart_args, false);
+ } else if (cc_cce_migrating(cc, direct)) {
+ KASSERT((c_flags & CALLOUT_LOCAL_ALLOC) == 0,
+ ("Migrating legacy callout %p", c));
+#ifdef SMP
+ /*
+ * If the callout was scheduled for
+ * migration just perform it now.
+ */
+ new_cpu = cc->cc_exec_entity[direct].ce_migration_cpu;
+ new_time = cc->cc_exec_entity[direct].ce_migration_time;
+ new_prec = cc->cc_exec_entity[direct].ce_migration_prec;
+ new_func = cc->cc_exec_entity[direct].ce_migration_func;
+ new_arg = cc->cc_exec_entity[direct].ce_migration_arg;
+ cc_cce_cleanup(cc, direct);
+
+ /*
+ * It should be assert here that the callout is not destroyed
+ * but that is not easy.
+ *
+ * As first thing, handle deferred callout stops.
+ */
+ if ((c->c_flags & CALLOUT_DFRMIGRATION) == 0) {
+ CTR3(KTR_CALLOUT,
+ "deferred cancelled %p func %p arg %p",
+ c, new_func, new_arg);
+ callout_cc_del(c, cc);
+ return;
+ }
+ c->c_flags &= ~CALLOUT_DFRMIGRATION;
+
+ new_cc = callout_cpu_switch(c, cc, new_cpu);
+ flags = (direct) ? C_DIRECT_EXEC : 0;
+ callout_cc_add(c, new_cc, new_time, new_prec, new_func,
+ new_arg, new_cpu, flags);
+ CC_UNLOCK(new_cc);
+ CC_LOCK(cc);
+#else
+ panic("migration should not happen");
+#endif
}
+ /*
+ * If the current callout is locally allocated (from
+ * timeout(9)) then put it on the freelist.
+ *
+ * Note: we need to check the cached copy of c_flags because
+ * if it was not local, then it's not safe to deref the
+ * callout pointer.
+ */
+ KASSERT((c_flags & CALLOUT_LOCAL_ALLOC) == 0 ||
+ c->c_flags == CALLOUT_LOCAL_ALLOC,
+ ("corrupted callout"));
+ if (c_flags & CALLOUT_LOCAL_ALLOC)
+ callout_cc_del(c, cc);
}
/*
@@ -933,11 +899,10 @@
/* XXX Attempt to malloc first */
panic("timeout table full");
SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle);
+ callout_reset(new, to_ticks, ftn, arg);
handle.callout = new;
CC_UNLOCK(cc);
- callout_reset(new, to_ticks, ftn, arg);
-
return (handle);
}
@@ -945,7 +910,6 @@
untimeout(timeout_t *ftn, void *arg, struct callout_handle handle)
{
struct callout_cpu *cc;
- bool match;
/*
* Check for a handle that was initialized
@@ -956,11 +920,9 @@
return;
cc = callout_lock(handle.callout);
- match = (handle.callout->c_func == ftn && handle.callout->c_arg == arg);
- CC_UNLOCK(cc);
-
- if (match)
+ if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
callout_stop(handle.callout);
+ CC_UNLOCK(cc);
}
void
@@ -969,119 +931,6 @@
handle->callout = NULL;
}
-static int
-callout_restart_async(struct callout *c, struct callout_args *coa,
- callout_func_t *drain_fn, void *drain_arg)
-{
- struct callout_cpu *cc;
- int cancelled;
- int direct;
-
- cc = callout_lock(c);
-
- /* Figure out if the callout is direct or not */
- direct = ((c->c_flags & CALLOUT_DIRECT) != 0);
-
- /*
- * Check if the callback is currently scheduled for
- * completion:
- */
- if (cc->cc_exec_entity[direct].cc_curr == c) {
- /*
- * Try to prevent the callback from running by setting
- * the "cc_cancel" variable to "true". Also check if
- * the callout was previously subject to a deferred
- * callout restart:
- */
- if (cc->cc_exec_entity[direct].cc_cancel == false ||
- (c->c_flags & CALLOUT_DEFRESTART) != 0) {
- cc->cc_exec_entity[direct].cc_cancel = true;
- cancelled = 1;
- } else {
- cancelled = 0;
- }
-
- /*
- * Prevent callback restart if "callout_drain_xxx()"
- * is being called or we are stopping the callout or
- * the callback was preallocated by us:
- */
- if (cc->cc_exec_entity[direct].cc_drain_fn != NULL ||
- coa == NULL || (c->c_flags & CALLOUT_LOCAL_ALLOC) != 0) {
- CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
- cancelled ? "cancelled and draining" : "draining",
- c, c->c_func, c->c_arg);
-
- /* clear old flags, if any */
- c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING |
- CALLOUT_DEFRESTART | CALLOUT_PROCESSED);
-
- /* clear restart flag, if any */
- cc->cc_exec_entity[direct].cc_restart = false;
-
- /* set drain function, if any */
- if (drain_fn != NULL) {
- cc->cc_exec_entity[direct].cc_drain_fn = drain_fn;
- cc->cc_exec_entity[direct].cc_drain_arg = drain_arg;
- cancelled |= 2; /* XXX define the value */
- }
- } else {
- CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
- cancelled ? "cancelled and restarting" : "restarting",
- c, c->c_func, c->c_arg);
-
- /* get us back into the game */
- c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING |
- CALLOUT_DEFRESTART);
- c->c_flags &= ~CALLOUT_PROCESSED;
-
- /* enable deferred restart */
- cc->cc_exec_entity[direct].cc_restart = true;
-
- /* store arguments for the deferred restart, if any */
- cc->cc_exec_entity[direct].cc_restart_args = *coa;
- }
- } else {
- /* stop callout */
- if (c->c_flags & CALLOUT_PENDING) {
- /*
- * The callback has not yet been executed, and
- * we simply just need to unlink it:
- */
- if ((c->c_flags & CALLOUT_PROCESSED) == 0) {
- if (cc->cc_exec_next_dir == c)
- cc->cc_exec_next_dir = LIST_NEXT(c, c_links.le);
- LIST_REMOVE(c, c_links.le);
- } else {
- TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
- }
- cancelled = 1;
- } else {
- cancelled = 0;
- }
-
- CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
- cancelled ? "rescheduled" : "scheduled",
- c, c->c_func, c->c_arg);
-
- /* [re-]schedule callout, if any */
- if (coa != NULL) {
- cc = callout_cc_add_locked(c, cc, coa, true);
- } else {
- /* clear old flags, if any */
- c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING |
- CALLOUT_DEFRESTART | CALLOUT_PROCESSED);
-
- /* return callback to pre-allocated list, if any */
- if ((c->c_flags & CALLOUT_LOCAL_ALLOC) && cancelled != 0) {
- callout_cc_del(c, cc);
- }
- }
- }
- CC_UNLOCK(cc);
- return (cancelled);
-}
-
/*
* New interface; clients allocate their own callout structures.
*
@@ -1100,32 +949,25 @@
*/
int
callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t precision,
- callout_func_t *ftn, void *arg, int cpu, int flags)
+ void (*ftn)(void *), void *arg, int cpu, int flags)
{
- struct callout_args coa;
+ sbintime_t to_sbt, pr;
+ struct callout_cpu *cc;
+ int cancelled, direct;
- /* store arguments for callout add function */
- coa.func = ftn;
- coa.arg = arg;
- coa.precision = precision;
- coa.flags = flags;
- coa.cpu = cpu;
-
- /* compute the rest of the arguments needed */
- if (coa.flags & C_ABSOLUTE) {
- coa.time = sbt;
+ cancelled = 0;
+ if (flags & C_ABSOLUTE) {
+ to_sbt = sbt;
} else {
- sbintime_t pr;
-
- if ((coa.flags & C_HARDCLOCK) && (sbt < tick_sbt))
+ if ((flags & C_HARDCLOCK) && (sbt < tick_sbt))
sbt = tick_sbt;
- if ((coa.flags & C_HARDCLOCK) ||
+ if ((flags & C_HARDCLOCK) ||
#ifdef NO_EVENTTIMERS
sbt >= sbt_timethreshold) {
- coa.time = getsbinuptime();
+ to_sbt = getsbinuptime();
/* Add safety belt for the case of hz > 1000. */
- coa.time += tc_tick_sbt - tick_sbt;
+ to_sbt += tc_tick_sbt - tick_sbt;
#else
sbt >= sbt_tickthreshold) {
/*
@@ -1135,29 +977,101 @@
* active ones.
*/
#ifdef __LP64__
- coa.time = DPCPU_GET(hardclocktime);
+ to_sbt = DPCPU_GET(hardclocktime);
#else
spinlock_enter();
- coa.time = DPCPU_GET(hardclocktime);
+ to_sbt = DPCPU_GET(hardclocktime);
spinlock_exit();
#endif
#endif
- if ((coa.flags & C_HARDCLOCK) == 0)
- coa.time += tick_sbt;
+ if ((flags & C_HARDCLOCK) == 0)
+ to_sbt += tick_sbt;
} else
- coa.time = sbinuptime();
- if (SBT_MAX - coa.time < sbt)
- coa.time = SBT_MAX;
+ to_sbt = sbinuptime();
+ if (SBT_MAX - to_sbt < sbt)
+ to_sbt = SBT_MAX;
else
- coa.time += sbt;
- pr = ((C_PRELGET(coa.flags) < 0) ? sbt >> tc_precexp :
- sbt >> C_PRELGET(coa.flags));
- if (pr > coa.precision)
- coa.precision = pr;
+ to_sbt += sbt;
+ pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp :
+ sbt >> C_PRELGET(flags));
+ if (pr > precision)
+ precision = pr;
+ }
+ /*
+ * Don't allow migration of pre-allocated callouts lest they
+ * become unbalanced.
+ */
+ if (c->c_flags & CALLOUT_LOCAL_ALLOC)
+ cpu = c->c_cpu;
+ direct = (c->c_flags & CALLOUT_DIRECT) != 0;
+ KASSERT(!direct || c->c_lock == NULL,
+ ("%s: direct callout %p has lock", __func__, c));
+ cc = callout_lock(c);
+ if (cc->cc_exec_entity[direct].cc_curr == c) {
+ /*
+ * We're being asked to reschedule a callout which is
+ * currently in progress. If there is a lock then we
+ * can cancel the callout if it has not really started.
+ */
+ if (c->c_lock != NULL && !cc->cc_exec_entity[direct].cc_cancel)
+ cancelled = cc->cc_exec_entity[direct].cc_cancel = true;
+ if (cc->cc_exec_entity[direct].cc_waiting) {
+ /*
+ * Someone has called callout_drain to kill this
+ * callout. Don't reschedule.
+ */
+ CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
+ cancelled ? "cancelled" : "failed to cancel",
+ c, c->c_func, c->c_arg);
+ CC_UNLOCK(cc);
+ return (cancelled);
+ }
+ }
+ if (c->c_flags & CALLOUT_PENDING) {
+ if ((c->c_flags & CALLOUT_PROCESSED) == 0) {
+ if (cc->cc_exec_next_dir == c)
+ cc->cc_exec_next_dir = LIST_NEXT(c, c_links.le);
+ LIST_REMOVE(c, c_links.le);
+ } else
+ TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
+ cancelled = 1;
+ c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
+ }
+
+#ifdef SMP
+ /*
+ * If the callout must migrate try to perform it immediately.
+ * If the callout is currently running, just defer the migration
+ * to a more appropriate moment.
+ */
+ if (c->c_cpu != cpu) {
+ if (cc->cc_exec_entity[direct].cc_curr == c) {
+ cc->cc_exec_entity[direct].ce_migration_cpu = cpu;
+ cc->cc_exec_entity[direct].ce_migration_time
+ = to_sbt;
+ cc->cc_exec_entity[direct].ce_migration_prec
+ = precision;
+ cc->cc_exec_entity[direct].ce_migration_func = ftn;
+ cc->cc_exec_entity[direct].ce_migration_arg = arg;
+ c->c_flags |= CALLOUT_DFRMIGRATION;
+ CTR6(KTR_CALLOUT,
+ "migration of %p func %p arg %p in %d.%08x to %u deferred",
+ c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
+ (u_int)(to_sbt & 0xffffffff), cpu);
+ CC_UNLOCK(cc);
+ return (cancelled);
+ }
+ cc = callout_cpu_switch(c, cc, cpu);
}
+#endif
+
+ callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags);
+ CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x",
+ cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
+ (u_int)(to_sbt & 0xffffffff));
+ CC_UNLOCK(cc);
- /* get callback started, if any */
- return (callout_restart_async(c, &coa, NULL, NULL));
+ return (cancelled);
}
/*
@@ -1176,105 +1090,204 @@
}
int
-callout_stop(struct callout *c)
+_callout_stop_safe(struct callout *c, int safe)
{
- /* get callback stopped, if any */
- return (callout_restart_async(c, NULL, NULL, NULL));
-}
-
-static void
-callout_drain_function(void *arg)
-{
- wakeup(arg);
-}
-
-int
-callout_drain_async(struct callout *c, callout_func_t *fn, void *arg)
-{
- /* get callback stopped, if any */
- return (callout_restart_async(c, NULL, fn, arg) & 2);
-}
-
-int
-callout_drain(struct callout *c)
-{
- int cancelled;
-
- WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
- "Draining callout");
-
- callout_lock_client(c->c_flags, c->c_lock);
-
- /* at this point the "c->c_cpu" field is not changing */
-
- cancelled = callout_drain_async(c, &callout_drain_function, c);
+ struct callout_cpu *cc, *old_cc;
+ struct lock_class *class;
+ int direct, sq_locked, use_lock;
- if (cancelled != 0) {
- struct callout_cpu *cc;
- int direct;
+ /*
+ * Some old subsystems don't hold Giant while running a callout_stop(),
+ * so just discard this check for the moment.
+ */
+ if (!safe && c->c_lock != NULL) {
+ if (c->c_lock == &Giant.lock_object)
+ use_lock = mtx_owned(&Giant);
+ else {
+ use_lock = 1;
+ class = LOCK_CLASS(c->c_lock);
+ class->lc_assert(c->c_lock, LA_XLOCKED);
+ }
+ } else
+ use_lock = 0;
+ direct = (c->c_flags & CALLOUT_DIRECT) != 0;
+ sq_locked = 0;
+ old_cc = NULL;
+again:
+ cc = callout_lock(c);
- CTR3(KTR_CALLOUT, "need to drain %p func %p arg %p",
- c, c->c_func, c->c_arg);
+ /*
+ * If the callout was migrating while the callout cpu lock was
+ * dropped, just drop the sleepqueue lock and check the states
+ * again.
+ */
+ if (sq_locked != 0 && cc != old_cc) {
+#ifdef SMP
+ CC_UNLOCK(cc);
+ sleepq_release(&old_cc->cc_exec_entity[direct].cc_waiting);
+ sq_locked = 0;
+ old_cc = NULL;
+ goto again;
+#else
+ panic("migration should not happen");
+#endif
+ }
- cc = callout_lock(c);
- direct = ((c->c_flags & CALLOUT_DIRECT) != 0);
+ /*
+ * If the callout isn't pending, it's not on the queue, so
+ * don't attempt to remove it from the queue. We can try to
+ * stop it by other means however.
+ */
+ if (!(c->c_flags & CALLOUT_PENDING)) {
+ c->c_flags &= ~CALLOUT_ACTIVE;
/*
- * We've gotten our callout CPU lock, it is safe to
- * drop the initial lock:
+ * If it wasn't on the queue and it isn't the current
+ * callout, then we can't stop it, so just bail.
*/
- callout_unlock_client(c->c_flags, c->c_lock);
-
- /* Wait for drain to complete */
+ if (cc->cc_exec_entity[direct].cc_curr != c) {
+ CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
+ c, c->c_func, c->c_arg);
+ CC_UNLOCK(cc);
+ if (sq_locked)
+ sleepq_release(
+ &cc->cc_exec_entity[direct].cc_waiting);
+ return (0);
+ }
- while (cc->cc_exec_entity[direct].cc_curr == c)
- msleep_spin(c, (struct mtx *)&cc->cc_lock, "codrain", 0);
+ if (safe) {
+ /*
+ * The current callout is running (or just
+ * about to run) and blocking is allowed, so
+ * just wait for the current invocation to
+ * finish.
+ */
+ while (cc->cc_exec_entity[direct].cc_curr == c) {
+ /*
+ * Use direct calls to sleepqueue interface
+ * instead of cv/msleep in order to avoid
+ * a LOR between cc_lock and sleepqueue
+ * chain spinlocks. This piece of code
+ * emulates a msleep_spin() call actually.
+ *
+ * If we already have the sleepqueue chain
+ * locked, then we can safely block. If we
+ * don't already have it locked, however,
+ * we have to drop the cc_lock to lock
+ * it. This opens several races, so we
+ * restart at the beginning once we have
+ * both locks. If nothing has changed, then
+ * we will end up back here with sq_locked
+ * set.
+ */
+ if (!sq_locked) {
+ CC_UNLOCK(cc);
+ sleepq_lock(
+ &cc->cc_exec_entity[direct].cc_waiting);
+ sq_locked = 1;
+ old_cc = cc;
+ goto again;
+ }
+ /*
+ * Migration could be cancelled here, but
+ * as long as it is still not sure when it
+ * will be packed up, just let softclock()
+ * take care of it.
+ */
+ cc->cc_exec_entity[direct].cc_waiting = true;
+ DROP_GIANT();
+ CC_UNLOCK(cc);
+ sleepq_add(
+ &cc->cc_exec_entity[direct].cc_waiting,
+ &cc->cc_lock.lock_object, "codrain",
+ SLEEPQ_SLEEP, 0);
+ sleepq_wait(
+ &cc->cc_exec_entity[direct].cc_waiting,
+ 0);
+ sq_locked = 0;
+ old_cc = NULL;
+
+ /* Reacquire locks previously released. */
+ PICKUP_GIANT();
+ CC_LOCK(cc);
+ }
+ } else if (use_lock &&
+ !cc->cc_exec_entity[direct].cc_cancel) {
+ /*
+ * The current callout is waiting for its
+ * lock which we hold. Cancel the callout
+ * and return. After our caller drops the
+ * lock, the callout will be skipped in
+ * softclock().
+ */
+ cc->cc_exec_entity[direct].cc_cancel = true;
+ CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
+ c, c->c_func, c->c_arg);
+ KASSERT(!cc_cce_migrating(cc, direct),
+ ("callout wrongly scheduled for migration"));
+ CC_UNLOCK(cc);
+ KASSERT(!sq_locked, ("sleepqueue chain locked"));
+ return (1);
+ } else if ((c->c_flags & CALLOUT_DFRMIGRATION) != 0) {
+ c->c_flags &= ~CALLOUT_DFRMIGRATION;
+ CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p",
+ c, c->c_func, c->c_arg);
+ CC_UNLOCK(cc);
+ return (1);
+ }
+ CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
+ c, c->c_func, c->c_arg);
CC_UNLOCK(cc);
- } else {
- callout_unlock_client(c->c_flags, c->c_lock);
+ KASSERT(!sq_locked, ("sleepqueue chain still locked"));
+ return (0);
}
+ if (sq_locked)
+ sleepq_release(&cc->cc_exec_entity[direct].cc_waiting);
+
+ c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
c, c->c_func, c->c_arg);
+ if ((c->c_flags & CALLOUT_PROCESSED) == 0) {
+ if (cc->cc_exec_next_dir == c)
+ cc->cc_exec_next_dir = LIST_NEXT(c, c_links.le);
+ LIST_REMOVE(c, c_links.le);
+ } else
+ TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
+ callout_cc_del(c, cc);
- return (cancelled & 1);
+ CC_UNLOCK(cc);
+ return (1);
}
void
callout_init(struct callout *c, int mpsafe)
{
+ bzero(c, sizeof *c);
if (mpsafe) {
- _callout_init_lock(c, NULL, CALLOUT_RETURNUNLOCKED);
+ c->c_lock = NULL;
+ c->c_flags = CALLOUT_RETURNUNLOCKED;
} else {
- _callout_init_lock(c, &Giant.lock_object, 0);
+ c->c_lock = &Giant.lock_object;
+ c->c_flags = 0;
}
+ c->c_cpu = timeout_cpu;
}
void
_callout_init_lock(struct callout *c, struct lock_object *lock, int flags)
{
bzero(c, sizeof *c);
- KASSERT((flags & ~CALLOUT_RETURNUNLOCKED) == 0,
- ("callout_init_lock: bad flags 0x%08x", flags));
- flags &= CALLOUT_RETURNUNLOCKED;
- if (lock != NULL) {
- struct lock_class *class = LOCK_CLASS(lock);
- if (class == &lock_class_mtx_sleep)
- flags |= CALLOUT_SET_LC(CALLOUT_LC_MUTEX);
- else if (class == &lock_class_mtx_spin)
- flags |= CALLOUT_SET_LC(CALLOUT_LC_SPIN);
- else if (class == &lock_class_rm)
- flags |= CALLOUT_SET_LC(CALLOUT_LC_RM);
- else if (class == &lock_class_rw)
- flags |= CALLOUT_SET_LC(CALLOUT_LC_RW);
- else
- panic("callout_init_lock: Unsupported lock class '%s'\n", class->lc_name);
- } else {
- flags |= CALLOUT_SET_LC(CALLOUT_LC_UNUSED_0);
- }
c->c_lock = lock;
- c->c_flags = flags;
+ KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0,
+ ("callout_init_lock: bad flags %d", flags));
+ KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0,
+ ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock"));
+ KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags &
+ (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class",
+ __func__));
+ c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK);
c->c_cpu = timeout_cpu;
}
Index: head/sys/kern/subr_sleepqueue.c
===================================================================
--- head/sys/kern/subr_sleepqueue.c
+++ head/sys/kern/subr_sleepqueue.c
@@ -152,8 +152,7 @@
*/
static int sleepq_catch_signals(void *wchan, int pri);
static int sleepq_check_signals(void);
-static int sleepq_check_timeout(struct thread *);
-static void sleepq_stop_timeout(struct thread *);
+static int sleepq_check_timeout(void);
#ifdef INVARIANTS
static void sleepq_dtor(void *mem, int size, void *arg);
#endif
@@ -374,14 +373,17 @@
sleepq_set_timeout_sbt(void *wchan, sbintime_t sbt, sbintime_t pr,
int flags)
{
+ struct sleepqueue_chain *sc;
struct thread *td;
td = curthread;
-
- mtx_lock_spin(&td->td_slpmutex);
+ sc = SC_LOOKUP(wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+ MPASS(TD_ON_SLEEPQ(td));
+ MPASS(td->td_sleepqueue == NULL);
+ MPASS(wchan != NULL);
callout_reset_sbt_on(&td->td_slpcallout, sbt, pr,
sleepq_timeout, td, PCPU_GET(cpuid), flags | C_DIRECT_EXEC);
- mtx_unlock_spin(&td->td_slpmutex);
}
/*
@@ -557,8 +559,11 @@
* Check to see if we timed out.
*/
static int
-sleepq_check_timeout(struct thread *td)
+sleepq_check_timeout(void)
{
+ struct thread *td;
+
+ td = curthread;
THREAD_LOCK_ASSERT(td, MA_OWNED);
/*
@@ -568,18 +573,25 @@
td->td_flags &= ~TDF_TIMEOUT;
return (EWOULDBLOCK);
}
- return (0);
-}
-/*
- * Atomically stop the timeout by using a mutex.
- */
-static void
-sleepq_stop_timeout(struct thread *td)
-{
- mtx_lock_spin(&td->td_slpmutex);
- callout_stop(&td->td_slpcallout);
- mtx_unlock_spin(&td->td_slpmutex);
+ /*
+ * If TDF_TIMOFAIL is set, the timeout ran after we had
+ * already been woken up.
+ */
+ if (td->td_flags & TDF_TIMOFAIL)
+ td->td_flags &= ~TDF_TIMOFAIL;
+
+ /*
+ * If callout_stop() fails, then the timeout is running on
+ * another CPU, so synchronize with it to avoid having it
+ * accidentally wake up a subsequent sleep.
+ */
+ else if (callout_stop(&td->td_slpcallout) == 0) {
+ td->td_flags |= TDF_TIMEOUT;
+ TD_SET_SLEEPING(td);
+ mi_switch(SW_INVOL | SWT_SLEEPQTIMO, NULL);
+ }
+ return (0);
}
/*
@@ -652,11 +664,9 @@
MPASS(!(td->td_flags & TDF_SINTR));
thread_lock(td);
sleepq_switch(wchan, pri);
- rval = sleepq_check_timeout(td);
+ rval = sleepq_check_timeout();
thread_unlock(td);
- sleepq_stop_timeout(td);
-
return (rval);
}
@@ -667,18 +677,12 @@
int
sleepq_timedwait_sig(void *wchan, int pri)
{
- struct thread *td;
int rcatch, rvalt, rvals;
- td = curthread;
-
rcatch = sleepq_catch_signals(wchan, pri);
- rvalt = sleepq_check_timeout(td);
+ rvalt = sleepq_check_timeout();
rvals = sleepq_check_signals();
- thread_unlock(td);
-
- sleepq_stop_timeout(td);
-
+ thread_unlock(curthread);
if (rcatch)
return (rcatch);
if (rvals)
@@ -885,49 +889,64 @@
static void
sleepq_timeout(void *arg)
{
- struct thread *td = arg;
- int wakeup_swapper = 0;
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+ struct thread *td;
+ void *wchan;
+ int wakeup_swapper;
+ td = arg;
+ wakeup_swapper = 0;
CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)",
(void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
- /* Handle the three cases which can happen */
-
+ /*
+ * First, see if the thread is asleep and get the wait channel if
+ * it is.
+ */
thread_lock(td);
- if (TD_ON_SLEEPQ(td)) {
- if (TD_IS_SLEEPING(td)) {
- struct sleepqueue_chain *sc;
- struct sleepqueue *sq;
- void *wchan;
+ if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) {
+ wchan = td->td_wchan;
+ sc = SC_LOOKUP(wchan);
+ THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock);
+ sq = sleepq_lookup(wchan);
+ MPASS(sq != NULL);
+ td->td_flags |= TDF_TIMEOUT;
+ wakeup_swapper = sleepq_resume_thread(sq, td, 0);
+ thread_unlock(td);
+ if (wakeup_swapper)
+ kick_proc0();
+ return;
+ }
- /*
- * Case I - thread is asleep and needs to be
- * awoken:
- */
- wchan = td->td_wchan;
- sc = SC_LOOKUP(wchan);
- THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock);
- sq = sleepq_lookup(wchan);
- MPASS(sq != NULL);
- td->td_flags |= TDF_TIMEOUT;
- wakeup_swapper = sleepq_resume_thread(sq, td, 0);
- } else {
- /*
- * Case II - cancel going to sleep by setting
- * the timeout flag because the target thread
- * is not asleep yet. It can be on another CPU
- * in between sleepq_add() and one of the
- * sleepq_*wait*() routines or it can be in
- * sleepq_catch_signals().
- */
- td->td_flags |= TDF_TIMEOUT;
- }
- } else {
- /*
- * Case III - thread is already woken up by a wakeup
- * call and should not timeout. Nothing to do!
- */
+ /*
+ * If the thread is on the SLEEPQ but isn't sleeping yet, it
+ * can either be on another CPU in between sleepq_add() and
+ * one of the sleepq_*wait*() routines or it can be in
+ * sleepq_catch_signals().
+ */
+ if (TD_ON_SLEEPQ(td)) {
+ td->td_flags |= TDF_TIMEOUT;
+ thread_unlock(td);
+ return;
}
+
+ /*
+ * Now check for the edge cases. First, if TDF_TIMEOUT is set,
+ * then the other thread has already yielded to us, so clear
+ * the flag and resume it. If TDF_TIMEOUT is not set, then the
+ * we know that the other thread is not on a sleep queue, but it
+ * hasn't resumed execution yet. In that case, set TDF_TIMOFAIL
+ * to let it know that the timeout has already run and doesn't
+ * need to be canceled.
+ */
+ if (td->td_flags & TDF_TIMEOUT) {
+ MPASS(TD_IS_SLEEPING(td));
+ td->td_flags &= ~TDF_TIMEOUT;
+ TD_CLR_SLEEPING(td);
+ wakeup_swapper = setrunnable(td);
+ } else
+ td->td_flags |= TDF_TIMOFAIL;
thread_unlock(td);
if (wakeup_swapper)
kick_proc0();
Index: head/sys/ofed/include/linux/completion.h
===================================================================
--- head/sys/ofed/include/linux/completion.h
+++ head/sys/ofed/include/linux/completion.h
@@ -105,9 +105,7 @@
if (c->done)
break;
sleepq_add(c, NULL, "completion", flags, 0);
- sleepq_release(c);
sleepq_set_timeout(c, end - ticks);
- sleepq_lock(c);
if (flags & SLEEPQ_INTERRUPTIBLE) {
if (sleepq_timedwait_sig(c, 0) != 0)
return (-ERESTARTSYS);
Index: head/sys/sys/_callout.h
===================================================================
--- head/sys/sys/_callout.h
+++ head/sys/sys/_callout.h
@@ -46,30 +46,19 @@
SLIST_HEAD(callout_slist, callout);
TAILQ_HEAD(callout_tailq, callout);
-typedef void callout_func_t(void *);
-
-struct callout_args {
- sbintime_t time; /* absolute time for the event */
- sbintime_t precision; /* delta allowed wrt opt */
- void *arg; /* function argument */
- callout_func_t *func; /* function to call */
- int flags; /* flags passed to callout_reset() */
- int cpu; /* CPU we're scheduled on */
-};
-
struct callout {
union {
LIST_ENTRY(callout) le;
SLIST_ENTRY(callout) sle;
TAILQ_ENTRY(callout) tqe;
} c_links;
- sbintime_t c_time; /* absolute time for the event */
+ sbintime_t c_time; /* ticks to the event */
sbintime_t c_precision; /* delta allowed wrt opt */
void *c_arg; /* function argument */
- callout_func_t *c_func; /* function to call */
- struct lock_object *c_lock; /* callback lock */
+ void (*c_func)(void *); /* function to call */
+ struct lock_object *c_lock; /* lock to handle */
int c_flags; /* state of this entry */
- int c_cpu; /* CPU we're scheduled on */
+ volatile int c_cpu; /* CPU we're scheduled on */
};
#endif
Index: head/sys/sys/callout.h
===================================================================
--- head/sys/sys/callout.h
+++ head/sys/sys/callout.h
@@ -45,12 +45,10 @@
#define CALLOUT_PENDING 0x0004 /* callout is waiting for timeout */
#define CALLOUT_MPSAFE 0x0008 /* callout handler is mp safe */
#define CALLOUT_RETURNUNLOCKED 0x0010 /* handler returns with mtx unlocked */
-#define CALLOUT_UNUSED_5 0x0020 /* --available-- */
-#define CALLOUT_DEFRESTART 0x0040 /* callout restart is deferred */
+#define CALLOUT_SHAREDLOCK 0x0020 /* callout lock held in shared mode */
+#define CALLOUT_DFRMIGRATION 0x0040 /* callout in deferred migration mode */
#define CALLOUT_PROCESSED 0x0080 /* callout in wheel or processing list? */
#define CALLOUT_DIRECT 0x0100 /* allow exec from hw int context */
-#define CALLOUT_SET_LC(x) (((x) & 7) << 16) /* set lock class */
-#define CALLOUT_GET_LC(x) (((x) >> 16) & 7) /* get lock class */
#define C_DIRECT_EXEC 0x0001 /* direct execution of callout */
#define C_PRELBITS 7
@@ -67,8 +65,7 @@
#ifdef _KERNEL
#define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE)
#define callout_deactivate(c) ((c)->c_flags &= ~CALLOUT_ACTIVE)
-int callout_drain(struct callout *);
-int callout_drain_async(struct callout *, callout_func_t *, void *);
+#define callout_drain(c) _callout_stop_safe(c, 1)
void callout_init(struct callout *, int);
void _callout_init_lock(struct callout *, struct lock_object *, int);
#define callout_init_mtx(c, mtx, flags) \
@@ -82,7 +79,7 @@
NULL, (flags))
#define callout_pending(c) ((c)->c_flags & CALLOUT_PENDING)
int callout_reset_sbt_on(struct callout *, sbintime_t, sbintime_t,
- callout_func_t *, void *, int, int);
+ void (*)(void *), void *, int, int);
#define callout_reset_sbt(c, sbt, pr, fn, arg, flags) \
callout_reset_sbt_on((c), (sbt), (pr), (fn), (arg), (c)->c_cpu, (flags))
#define callout_reset_sbt_curcpu(c, sbt, pr, fn, arg, flags) \
@@ -106,7 +103,8 @@
int callout_schedule_on(struct callout *, int, int);
#define callout_schedule_curcpu(c, on_tick) \
callout_schedule_on((c), (on_tick), PCPU_GET(cpuid))
-int callout_stop(struct callout *);
+#define callout_stop(c) _callout_stop_safe(c, 0)
+int _callout_stop_safe(struct callout *, int);
void callout_process(sbintime_t now);
#endif
Index: head/sys/sys/param.h
===================================================================
--- head/sys/sys/param.h
+++ head/sys/sys/param.h
@@ -58,7 +58,7 @@
* in the range 5 to 9.
*/
#undef __FreeBSD_version
-#define __FreeBSD_version 1100054 /* Master, propagated to newvers */
+#define __FreeBSD_version 1100055 /* Master, propagated to newvers */
/*
* __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
Index: head/sys/sys/proc.h
===================================================================
--- head/sys/sys/proc.h
+++ head/sys/sys/proc.h
@@ -308,7 +308,6 @@
} td_uretoff; /* (k) Syscall aux returns. */
#define td_retval td_uretoff.tdu_retval
struct callout td_slpcallout; /* (h) Callout for sleep. */
- struct mtx td_slpmutex; /* (h) Mutex for sleep callout */
struct trapframe *td_frame; /* (k) */
struct vm_object *td_kstack_obj;/* (a) Kstack object. */
vm_offset_t td_kstack; /* (a) Kernel VA of kstack. */
@@ -365,7 +364,7 @@
#define TDF_ALLPROCSUSP 0x00000200 /* suspended by SINGLE_ALLPROC */
#define TDF_BOUNDARY 0x00000400 /* Thread suspended at user boundary */
#define TDF_ASTPENDING 0x00000800 /* Thread has some asynchronous events. */
-#define TDF_UNUSED12 0x00001000 /* --available-- */
+#define TDF_TIMOFAIL 0x00001000 /* Timeout from sleep after we were awake. */
#define TDF_SBDRY 0x00002000 /* Stop only on usermode boundary. */
#define TDF_UPIBLOCKED 0x00004000 /* Thread blocked on user PI mutex. */
#define TDF_NEEDSUSPCHK 0x00008000 /* Thread may need to suspend. */
@@ -707,7 +706,7 @@
#define SWT_OWEPREEMPT 2 /* Switching due to opepreempt. */
#define SWT_TURNSTILE 3 /* Turnstile contention. */
#define SWT_SLEEPQ 4 /* Sleepq wait. */
-#define SWT_UNUSED5 5 /* --available-- */
+#define SWT_SLEEPQTIMO 5 /* Sleepq timeout wait. */
#define SWT_RELINQUISH 6 /* yield call. */
#define SWT_NEEDRESCHED 7 /* NEEDRESCHED was set. */
#define SWT_IDLE 8 /* Switching from the idle thread. */

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