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Index: head/sys/kern/uipc_usrreq.c
===================================================================
--- head/sys/kern/uipc_usrreq.c
+++ head/sys/kern/uipc_usrreq.c
@@ -260,7 +260,7 @@
#define UNP_LINK_LOCK_INIT() rw_init(&unp_link_rwlock, \
"unp_link_rwlock")
-#define UNP_LINK_LOCK_ASSERT() rw_assert(&unp_link_rwlock, \
+#define UNP_LINK_LOCK_ASSERT() rw_assert(&unp_link_rwlock, \
RA_LOCKED)
#define UNP_LINK_UNLOCK_ASSERT() rw_assert(&unp_link_rwlock, \
RA_UNLOCKED)
@@ -778,6 +778,8 @@
UNP_LINK_WLOCK();
LIST_REMOVE(unp, unp_link);
+ if (unp->unp_gcflag & UNPGC_DEAD)
+ LIST_REMOVE(unp, unp_dead);
unp->unp_gencnt = ++unp_gencnt;
--unp_count;
UNP_LINK_WUNLOCK();
@@ -2481,50 +2483,61 @@
* synchronization.
*/
static int unp_marked;
-static int unp_unreachable;
static void
-unp_accessable(struct filedescent **fdep, int fdcount)
+unp_remove_dead_ref(struct filedescent **fdep, int fdcount)
{
struct unpcb *unp;
struct file *fp;
int i;
+ /*
+ * This function can only be called from the gc task.
+ */
+ KASSERT(taskqueue_member(taskqueue_thread, curthread) != 0,
+ ("%s: not on gc callout", __func__));
+ UNP_LINK_LOCK_ASSERT();
+
for (i = 0; i < fdcount; i++) {
fp = fdep[i]->fde_file;
if ((unp = fptounp(fp)) == NULL)
continue;
- if (unp->unp_gcflag & UNPGC_REF)
+ if ((unp->unp_gcflag & UNPGC_DEAD) == 0)
continue;
- unp->unp_gcflag &= ~UNPGC_DEAD;
- unp->unp_gcflag |= UNPGC_REF;
- unp_marked++;
+ unp->unp_gcrefs--;
}
}
static void
-unp_gc_process(struct unpcb *unp)
+unp_restore_undead_ref(struct filedescent **fdep, int fdcount)
{
- struct socket *so, *soa;
+ struct unpcb *unp;
struct file *fp;
+ int i;
- /* Already processed. */
- if (unp->unp_gcflag & UNPGC_SCANNED)
- return;
- fp = unp->unp_file;
-
/*
- * Check for a socket potentially in a cycle. It must be in a
- * queue as indicated by msgcount, and this must equal the file
- * reference count. Note that when msgcount is 0 the file is NULL.
+ * This function can only be called from the gc task.
*/
- if ((unp->unp_gcflag & UNPGC_REF) == 0 && fp &&
- unp->unp_msgcount != 0 && fp->f_count == unp->unp_msgcount) {
- unp->unp_gcflag |= UNPGC_DEAD;
- unp_unreachable++;
- return;
+ KASSERT(taskqueue_member(taskqueue_thread, curthread) != 0,
+ ("%s: not on gc callout", __func__));
+ UNP_LINK_LOCK_ASSERT();
+
+ for (i = 0; i < fdcount; i++) {
+ fp = fdep[i]->fde_file;
+ if ((unp = fptounp(fp)) == NULL)
+ continue;
+ if ((unp->unp_gcflag & UNPGC_DEAD) == 0)
+ continue;
+ unp->unp_gcrefs++;
+ unp_marked++;
}
+}
+static void
+unp_gc_scan(struct unpcb *unp, void (*op)(struct filedescent **, int))
+{
+ struct socket *so, *soa;
+
so = unp->unp_socket;
SOCK_LOCK(so);
if (SOLISTENING(so)) {
@@ -2535,7 +2548,7 @@
if (sotounpcb(soa)->unp_gcflag & UNPGC_IGNORE_RIGHTS)
continue;
SOCKBUF_LOCK(&soa->so_rcv);
- unp_scan(soa->so_rcv.sb_mb, unp_accessable);
+ unp_scan(soa->so_rcv.sb_mb, op);
SOCKBUF_UNLOCK(&soa->so_rcv);
}
} else {
@@ -2544,12 +2557,11 @@
*/
if ((unp->unp_gcflag & UNPGC_IGNORE_RIGHTS) == 0) {
SOCKBUF_LOCK(&so->so_rcv);
- unp_scan(so->so_rcv.sb_mb, unp_accessable);
+ unp_scan(so->so_rcv.sb_mb, op);
SOCKBUF_UNLOCK(&so->so_rcv);
}
}
SOCK_UNLOCK(so);
- unp->unp_gcflag |= UNPGC_SCANNED;
}
static int unp_recycled;
@@ -2560,67 +2572,115 @@
SYSCTL_INT(_net_local, OID_AUTO, taskcount, CTLFLAG_RD, &unp_taskcount, 0,
"Number of times the garbage collector has run.");
+SYSCTL_UINT(_net_local, OID_AUTO, sockcount, CTLFLAG_RD, &unp_count, 0,
+ "Number of active local sockets.");
+
static void
unp_gc(__unused void *arg, int pending)
{
struct unp_head *heads[] = { &unp_dhead, &unp_shead, &unp_sphead,
NULL };
struct unp_head **head;
+ struct unp_head unp_deadhead; /* List of potentially-dead sockets. */
struct file *f, **unref;
- struct unpcb *unp;
- int i, total;
+ struct unpcb *unp, *unptmp;
+ int i, total, unp_unreachable;
+ LIST_INIT(&unp_deadhead);
unp_taskcount++;
UNP_LINK_RLOCK();
/*
- * First clear all gc flags from previous runs, apart from
- * UNPGC_IGNORE_RIGHTS.
+ * First determine which sockets may be in cycles.
*/
+ unp_unreachable = 0;
+
for (head = heads; *head != NULL; head++)
- LIST_FOREACH(unp, *head, unp_link)
- unp->unp_gcflag =
- (unp->unp_gcflag & UNPGC_IGNORE_RIGHTS);
+ LIST_FOREACH(unp, *head, unp_link) {
+ KASSERT((unp->unp_gcflag & ~UNPGC_IGNORE_RIGHTS) == 0,
+ ("%s: unp %p has unexpected gc flags 0x%x",
+ __func__, unp, (unsigned int)unp->unp_gcflag));
+
+ f = unp->unp_file;
+
+ /*
+ * Check for an unreachable socket potentially in a
+ * cycle. It must be in a queue as indicated by
+ * msgcount, and this must equal the file reference
+ * count. Note that when msgcount is 0 the file is
+ * NULL.
+ */
+ if (f != NULL && unp->unp_msgcount != 0 &&
+ f->f_count == unp->unp_msgcount) {
+ LIST_INSERT_HEAD(&unp_deadhead, unp, unp_dead);
+ unp->unp_gcflag |= UNPGC_DEAD;
+ unp->unp_gcrefs = unp->unp_msgcount;
+ unp_unreachable++;
+ }
+ }
+
/*
- * Scan marking all reachable sockets with UNPGC_REF. Once a socket
- * is reachable all of the sockets it references are reachable.
+ * Scan all sockets previously marked as potentially being in a cycle
+ * and remove the references each socket holds on any UNPGC_DEAD
+ * sockets in its queue. After this step, all remaining references on
+ * sockets marked UNPGC_DEAD should not be part of any cycle.
+ */
+ LIST_FOREACH(unp, &unp_deadhead, unp_dead)
+ unp_gc_scan(unp, unp_remove_dead_ref);
+
+ /*
+ * If a socket still has a non-negative refcount, it cannot be in a
+ * cycle. In this case increment refcount of all children iteratively.
* Stop the scan once we do a complete loop without discovering
* a new reachable socket.
*/
do {
- unp_unreachable = 0;
unp_marked = 0;
- for (head = heads; *head != NULL; head++)
- LIST_FOREACH(unp, *head, unp_link)
- unp_gc_process(unp);
+ LIST_FOREACH_SAFE(unp, &unp_deadhead, unp_dead, unptmp)
+ if (unp->unp_gcrefs > 0) {
+ unp->unp_gcflag &= ~UNPGC_DEAD;
+ LIST_REMOVE(unp, unp_dead);
+ KASSERT(unp_unreachable > 0,
+ ("%s: unp_unreachable underflow.",
+ __func__));
+ unp_unreachable--;
+ unp_gc_scan(unp, unp_restore_undead_ref);
+ }
} while (unp_marked);
+
UNP_LINK_RUNLOCK();
+
if (unp_unreachable == 0)
return;
/*
- * Allocate space for a local list of dead unpcbs.
+ * Allocate space for a local array of dead unpcbs.
+ * TODO: can this path be simplified by instead using the local
+ * dead list at unp_deadhead, after taking out references
+ * on the file object and/or unpcb and dropping the link lock?
*/
unref = malloc(unp_unreachable * sizeof(struct file *),
M_TEMP, M_WAITOK);
/*
* Iterate looking for sockets which have been specifically marked
- * as as unreachable and store them locally.
+ * as unreachable and store them locally.
*/
UNP_LINK_RLOCK();
- for (total = 0, head = heads; *head != NULL; head++)
- LIST_FOREACH(unp, *head, unp_link)
- if ((unp->unp_gcflag & UNPGC_DEAD) != 0) {
- f = unp->unp_file;
- if (unp->unp_msgcount == 0 || f == NULL ||
- f->f_count != unp->unp_msgcount ||
- !fhold(f))
- continue;
- unref[total++] = f;
- KASSERT(total <= unp_unreachable,
- ("unp_gc: incorrect unreachable count."));
- }
+ total = 0;
+ LIST_FOREACH(unp, &unp_deadhead, unp_dead) {
+ KASSERT((unp->unp_gcflag & UNPGC_DEAD) != 0,
+ ("%s: unp %p not marked UNPGC_DEAD", __func__, unp));
+ unp->unp_gcflag &= ~UNPGC_DEAD;
+ f = unp->unp_file;
+ if (unp->unp_msgcount == 0 || f == NULL ||
+ f->f_count != unp->unp_msgcount ||
+ !fhold(f))
+ continue;
+ unref[total++] = f;
+ KASSERT(total <= unp_unreachable,
+ ("%s: incorrect unreachable count.", __func__));
+ }
UNP_LINK_RUNLOCK();
/*
Index: head/sys/sys/unpcb.h
===================================================================
--- head/sys/sys/unpcb.h
+++ head/sys/sys/unpcb.h
@@ -86,7 +86,9 @@
unp_gen_t unp_gencnt; /* generation count of this instance */
struct file *unp_file; /* back-pointer to file for gc. */
u_int unp_msgcount; /* references from message queue */
+ u_int unp_gcrefs; /* garbage collector refcount */
ino_t unp_ino; /* fake inode number */
+ LIST_ENTRY(unpcb) unp_dead; /* link in dead list */
} __aligned(CACHE_LINE_SIZE);
/*
@@ -113,10 +115,8 @@
/*
* Flags in unp_gcflag.
*/
-#define UNPGC_REF 0x1 /* unpcb has external ref. */
-#define UNPGC_DEAD 0x2 /* unpcb might be dead. */
-#define UNPGC_SCANNED 0x4 /* Has been scanned. */
-#define UNPGC_IGNORE_RIGHTS 0x8 /* Attached rights are freed */
+#define UNPGC_DEAD 0x1 /* unpcb might be dead. */
+#define UNPGC_IGNORE_RIGHTS 0x2 /* Attached rights are freed */
#define sotounpcb(so) ((struct unpcb *)((so)->so_pcb))

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