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authorLinus Torvalds <torvalds@linux-foundation.org>2008-08-11 16:46:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-08-11 16:46:11 -0700
commit67a077dca4e648a662e32cbeaaba8094d2e30229 (patch)
tree2f8943838b73b0a8ea590b1aaad9294eb280ea1e /kernel/posix-timers.c
parent9b4d0bab32e18e4f72781f9fa309a81495b2aff3 (diff)
parent2106b531eaa2edd0c2dfa735a0556c08c7ba3c86 (diff)
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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
* '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
Diffstat (limited to 'kernel/posix-timers.c')
-rw-r--r--kernel/posix-timers.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 9a21681aa80f..e36d5798cbff 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -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;
}