Differential D32462 Diff 96717 share/man/man3/pthread_mutex_init.3

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share/man/man3/pthread_mutex_init.3

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	If	If
	.Fa attr	.Fa attr
	is NULL the default attributes are used.	is NULL the default attributes are used.
		.Bd -literal
		struct pthread_mutex_attr {
		enum pthread_mutextype m_type;
		int m_protocol;
		int m_ceiling;
		int m_pshared;
		int m_robust;
		};
		.Ed
		.Pp
		.Va m_type
		can have the following values:
		.Bl -tag -width "PTHREAD_MUTEX_ADAPTIVE_NP"
		.It Dv PTHREAD_MUTEX_ERRORCHECK
		Provide error checking.
		This is the default.
		An error will be returned when attempting to relock a mutex without
		first unlocking it, when attempting to unlock a mutex which another
		thread has locked, or when attempting to unlock an unlocked mutex.
		.It Dv PTHREAD_MUTEX_DEFAULT
		Use the implementation default scheduling.
		For
		.Fx ,
		this is PTHREAD_MUTEX_ERRORCHECK.
		.It Dv PTHREAD_MUTEX_RECURSIVE
		A recursive mutex.
		Multiple locks of this mutex will require the same number of unlocks
		to release the mutex before another thread can acquire the mutex.
		A thread attempting to unlock a mutex held by another thread will
		return with an error.
		.It Dv PTHREAD_MUTEX_NORMAL
		Do not check for deadlock.
		A thread attempting to relock this mutex without first unlocking
		it will deadlock.
		Attempting to unlock a thread mutex locked by a different thread,
		or attempting to unlock an unlocked mutex results in undefined behavior.
		This is the default.
		.It Dv PTHREAD_MUTEX_ADAPTIVE_NP
		Adaptive mutex, spins briefly before blocking on lock.
		.El
		.Pp
		.Va m_protocol
		can have the following values:
		.Bl -tag -width "PTHREAD_PRIO_PROTECT"
		.It Dv PTHREAD_PRIO_NONE
		Scheduling and priority of a thread are not affected by its mutex
		ownership.
		.It Dv PTHREAD_PRIO_INHERIT
		Execute the thread at the higher of the thread's priority or the
		highest priority thread waiting on any of the mutexes owned by this
		thread and initialized with this protocol.
		.It Dv PTHREAD_PRIO_PROTECT
		Execute the thread at the higher of its priority or the highest of
		the priority ceilings of all the mutexes owned by this thread and
		initialized with this attribute, regardless of whether other threads
		are blocked on any of these mutexes or not.
		.El
		.Pp
		If a thread simultaneously owns several mutexes initialized with
		different protocols, it will execute at the highest priority that
		it would have obtained by each of these protocols.
		.Pp
		.Va m_ceiling
		defines the priority ceiling of initialized mutexes, which is the
		minimum priority level at which the critical section guarded by a
		mutex is executed.
		Defined values include:
		.Pp
		.Bl -tag -width "SCHED_OTHER"
		.It Dv SCHED_FIFO
		First in-first out (FIFO) fixed priority scheduling policy
		with no round-robin scheduling.
		If the thread is not interrupted by a higher-priority thread, the
		thread will proceed to completion.
		.It Dv SCHED_OTHER
		The standard time sharing scheduler.
		.It Dv SCHED_RR
		Round-robin scheduling across same priority processes.
		If the thread is not interrupted by a higher-priority thread, the
		thread will execute for a time determined by the system.
		.El
		.Pp
		.Va m_pshared
		is the
		.Em process-shared
		attribute and can have the following values:
		.Bl -tag -width "PTHREAD_PROCESS_PRIVATE"
		.It Dv PTHREAD_PROCESS_PRIVATE
		The mutex can only be operated on by threads created within the
		same process as the thread that initialized the mutex.
		Threads of differing processes attempting to access a mutex
		with this set results in undefined behavior.
		This is the default.
		.It Dv PTHREAD_PROCESS_SHARED
		Any thread that has access to the memory where mutex is allocated
		can operate on this mutex, even if the memory is shared by
		multiple processes.
		.El
	.Sh RETURN VALUES	.Sh RETURN VALUES
	If successful,	If successful,
	.Fn pthread_mutex_init	.Fn pthread_mutex_init
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