Date: Tue, 16 Nov 2010 01:56:19 +0000 (UTC) From: David Xu <davidxu@FreeBSD.org> To: src-committers@freebsd.org, svn-src-user@freebsd.org Subject: svn commit: r215364 - user/davidxu/libthr/sys/kern Message-ID: <201011160156.oAG1uJLE035598@svn.freebsd.org>
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Author: davidxu Date: Tue Nov 16 01:56:19 2010 New Revision: 215364 URL: http://svn.freebsd.org/changeset/base/215364 Log: Because umtx_thread_cleanup() no longer is called with process lock held, There is a race that a thread is exiting while another thread tries to add an entry into its mutex contention list, add uq_exiting flag to indicating that a thread is exiting, and a PI entry should not be added to the thread. Modified: user/davidxu/libthr/sys/kern/kern_umtx.c Modified: user/davidxu/libthr/sys/kern/kern_umtx.c ============================================================================== --- user/davidxu/libthr/sys/kern/kern_umtx.c Tue Nov 16 00:32:45 2010 (r215363) +++ user/davidxu/libthr/sys/kern/kern_umtx.c Tue Nov 16 01:56:19 2010 (r215364) @@ -165,7 +165,11 @@ struct umtx_q { int uq_repair_mutex; + /* Robust mutex list */ struct robust_list uq_rob_list; + + /* Thread is exiting. */ + char uq_exiting; }; TAILQ_HEAD(umtxq_head, umtx_q); @@ -324,6 +328,8 @@ static void umtx_thread_cleanup(struct t static void umtx_exec_hook(void *arg __unused, struct proc *p __unused, struct image_params *imgp __unused); static void umtx_exit_hook(void *arg __unused, struct proc *p __unused); +static void umtx_fork_hook(void *arg __unused, struct proc *p1 __unused, + struct proc *p2, int flags __unused); static int robust_alloc(struct robust_info **); static void robust_free(struct robust_info *); static int robust_insert(struct thread *, struct robust_info *); @@ -372,6 +378,8 @@ umtxq_sysinit(void *arg __unused) EVENTHANDLER_PRI_ANY); EVENTHANDLER_REGISTER(process_exit, umtx_exit_hook, NULL, EVENTHANDLER_PRI_ANY); + EVENTHANDLER_REGISTER(process_fork, umtx_fork_hook, NULL, + EVENTHANDLER_PRI_ANY); max_robust_interval.tv_sec = 10; max_robust_interval.tv_usec = 0; @@ -1791,11 +1799,14 @@ umtxq_sleep_pi(struct umtx_q *uq, struct /* XXX Only look up thread in current process. */ td1 = tdfind(owner, curproc->p_pid); mtx_lock_spin(&umtx_lock); - if (td1 != NULL && pi->pi_owner == NULL) { - uq1 = td1->td_umtxq; - umtx_pi_setowner(pi, td1); + if (td1 != NULL) { + if((uq1 = td1->td_umtxq) != NULL && + uq1->uq_exiting == 0) { + if (pi->pi_owner == NULL) + umtx_pi_setowner(pi, td1); + } + PROC_UNLOCK(td1->td_proc); } - PROC_UNLOCK(td1->td_proc); } TAILQ_FOREACH(uq1, &pi->pi_blocked, uq_lockq) { @@ -4351,6 +4362,7 @@ umtx_thread_alloc(struct thread *td) uq = td->td_umtxq; uq->uq_inherited_pri = PRI_MAX; + uq->uq_exiting = 0; KASSERT(uq->uq_flags == 0, ("uq_flags != 0")); KASSERT(uq->uq_thread == td, ("uq_thread != td")); @@ -4374,7 +4386,27 @@ umtx_exec_hook(void *arg __unused, struc static void umtx_exit_hook(void *arg __unused, struct proc *p __unused) { - umtx_thread_cleanup(curthread); + struct umtx_q *uq = curthread->td_umtxq; + + if (uq != NULL) { + uq->uq_exiting = 1; + umtx_thread_cleanup(curthread); + } +} + +/* + * fork() hook. First thread of process never call umtx_thread_alloc() + * again, we should clear uq_exiting here. + */ +void +umtx_fork_hook(void *arg __unused, struct proc *p1 __unused, + struct proc *p2, int flags __unused) +{ + struct thread *td = FIRST_THREAD_IN_PROC(p2); + struct umtx_q *uq = td->td_umtxq; + + if (uq != NULL) + uq->uq_exiting = 0; } /*
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