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Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  posix-timers: fix posix_timer_event() vs dequeue_signal() race
  posix-timers: do_schedule_next_timer: fix the setting of ->si_overrun
This commit is contained in:
Linus Torvalds 2008-08-11 16:46:11 -07:00
commit 67a077dca4
2 changed files with 15 additions and 5 deletions
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19
kernel/posix-timers.c
View file

@ -289,21 +289,29 @@ void do_schedule_next_timer(struct siginfo *info)
else
schedule_next_timer(timr);
info->si_overrun = timr->it_overrun_last;
info->si_overrun += timr->it_overrun_last;
}
if (timr)
unlock_timer(timr, flags);
}
int posix_timer_event(struct k_itimer *timr,int si_private)
int posix_timer_event(struct k_itimer *timr, int si_private)
{
memset(&timr->sigq->info, 0, sizeof(siginfo_t));
/*
* FIXME: if ->sigq is queued we can race with
* dequeue_signal()->do_schedule_next_timer().
*
* If dequeue_signal() sees the "right" value of
* si_sys_private it calls do_schedule_next_timer().
* We re-queue ->sigq and drop ->it_lock().
* do_schedule_next_timer() locks the timer
* and re-schedules it while ->sigq is pending.
* Not really bad, but not that we want.
*/
timr->sigq->info.si_sys_private = si_private;
/* Send signal to the process that owns this timer.*/
timr->sigq->info.si_signo = timr->it_sigev_signo;
timr->sigq->info.si_errno = 0;
timr->sigq->info.si_code = SI_TIMER;
timr->sigq->info.si_tid = timr->it_id;
timr->sigq->info.si_value = timr->it_sigev_value;
@ -435,6 +443,7 @@ static struct k_itimer * alloc_posix_timer(void)
kmem_cache_free(posix_timers_cache, tmr);
tmr = NULL;
}
memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
return tmr;
}

1
kernel/signal.c
View file

@ -1304,6 +1304,7 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
q->info.si_overrun++;
goto out;
}
q->info.si_overrun = 0;
signalfd_notify(t, sig);
pending = group ? &t->signal->shared_pending : &t->pending;