Date: Fri, 18 Nov 2011 09:12:26 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r227657 - in head/sys: kern sys Message-ID: <201111180912.pAI9CQ8V062873@svn.freebsd.org>
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Author: kib Date: Fri Nov 18 09:12:26 2011 New Revision: 227657 URL: http://svn.freebsd.org/changeset/base/227657 Log: Consistently use process spin lock for protection of the p->p_boundary_count. Race could cause the execve(2) from the threaded process to hung since thread boundary counter was incorrect and single-threading never finished. Reported by: pluknet, pho Tested by: pho MFC after: 1 week Modified: head/sys/kern/kern_thread.c head/sys/sys/proc.h Modified: head/sys/kern/kern_thread.c ============================================================================== --- head/sys/kern/kern_thread.c Fri Nov 18 09:05:25 2011 (r227656) +++ head/sys/kern/kern_thread.c Fri Nov 18 09:12:26 2011 (r227657) @@ -566,6 +566,8 @@ calc_remaining(struct proc *p, int mode) { int remaining; + PROC_LOCK_ASSERT(p, MA_OWNED); + PROC_SLOCK_ASSERT(p, MA_OWNED); if (mode == SINGLE_EXIT) remaining = p->p_numthreads; else if (mode == SINGLE_BOUNDARY) @@ -819,8 +821,11 @@ thread_suspend_check(int return_instead) td->td_flags &= ~TDF_BOUNDARY; thread_unlock(td); PROC_LOCK(p); - if (return_instead == 0) + if (return_instead == 0) { + PROC_SLOCK(p); p->p_boundary_count--; + PROC_SUNLOCK(p); + } } return (0); } Modified: head/sys/sys/proc.h ============================================================================== --- head/sys/sys/proc.h Fri Nov 18 09:05:25 2011 (r227656) +++ head/sys/sys/proc.h Fri Nov 18 09:12:26 2011 (r227657) @@ -532,7 +532,7 @@ struct proc { struct thread *p_singlethread;/* (c + j) If single threading this is it */ int p_suspcount; /* (j) Num threads in suspended mode. */ struct thread *p_xthread; /* (c) Trap thread */ - int p_boundary_count;/* (c) Num threads at user boundary */ + int p_boundary_count;/* (j) Num threads at user boundary */ int p_pendingcnt; /* how many signals are pending */ struct itimers *p_itimers; /* (c) POSIX interval timers. */ struct procdesc *p_procdesc; /* (e) Process descriptor, if any. */
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