Messages in this thread Patch in this message | | | Subject | Re: [PATCH] fix send_sigqueue() vs thread exit race | From | Thomas Gleixner <> | Date | Sun, 21 Aug 2005 23:50:32 +0200 |
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On Sun, 2005-08-21 at 23:24 +0200, Thomas Gleixner wrote: > Oleg,
Sorry for making noise. I introduced the race again.
tglx
--- linux-2.6.13-rc6.signal/kernel/signal.oleg.c 2005-08-21 23:07:03.000000000 +0200 +++ linux-2.6.13-rc6.signal/kernel/signal.c 2005-08-21 23:48:52.000000000 +0200 @@ -1381,8 +1381,15 @@ send_sigqueue(int sig, struct sigqueue * int ret = 0; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); - read_lock(&tasklist_lock); +retry: + if (unlikely(p->flags & PF_EXITING)) + return -1; + + if (unlikely(!read_trylock(&tasklist_lock))) { + cpu_relax(); + goto retry; + } if (unlikely(p->flags & PF_EXITING)) { ret = -1; goto out_err; @@ -1427,7 +1434,18 @@ send_group_sigqueue(int sig, struct sigq int ret = 0; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); - read_lock(&tasklist_lock); +retry: + if (unlikely(p->flags & PF_EXITING)) + return -1; + + if (unlikely(!read_trylock(&tasklist_lock))) { + cpu_relax(); + goto retry; + } + if (unlikely(p->flags & PF_EXITING)) { + ret = -1; + goto out_err; + } spin_lock_irqsave(&p->sighand->siglock, flags); handle_stop_signal(sig, p); @@ -1461,8 +1479,9 @@ send_group_sigqueue(int sig, struct sigq __group_complete_signal(sig, p); out: spin_unlock_irqrestore(&p->sighand->siglock, flags); +out_err: read_unlock(&tasklist_lock); - return(ret); + return ret; } /* --- linux-2.6.13-rc6.signal/kernel/posix-timers.oleg.c 2005-08-21 23:09:58.000000000 +0200 +++ linux-2.6.13-rc6.signal/kernel/posix-timers.c 2005-08-21 23:19:42.000000000 +0200 @@ -501,7 +501,8 @@ static void posix_timer_fn(unsigned long remove_from_abslist(timr); } - if (posix_timer_event(timr, si_private)) + /* Do not rearm the timer, when we are exiting */ + if (posix_timer_event(timr, si_private) > 0) /* * signal was not sent because of sig_ignor * we will not get a call back to restart it AND
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