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os: make timers signal-safe 

If TimerSet() is called from a signal handler (synaptics tap handling code)
may result in list corruption if we're currently inside TimerSet().

See backtrace in
https://bugzilla.redhat.com/show_bug.cgi?id=814869

Block signals for all list manipulations in the timers.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Chase Douglas <chase.douglas@canonical.com>
This commit is contained in:
Peter Hutterer 2012-04-27 10:52:39 +10:00
parent d662fa2450
commit 08962951de
1 changed files with 16 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
os/WaitFor.c
View File

@ -382,6 +382,7 @@ CheckAllTimers(void)
OsTimerPtr timer; OsTimerPtr timer;
CARD32 now; CARD32 now;
OsBlockSignals();
start: start:
now = GetTimeInMillis(); now = GetTimeInMillis();
@ -391,6 +392,7 @@ CheckAllTimers(void)
goto start; goto start;
} }
} }
OsReleaseSignals();
} }
static void static void
@ -398,11 +400,13 @@ DoTimer(OsTimerPtr timer, CARD32 now, OsTimerPtr *prev)
{ {
CARD32 newTime; CARD32 newTime;
OsBlockSignals();
*prev = timer->next; *prev = timer->next;
timer->next = NULL; timer->next = NULL;
newTime = (*timer->callback) (timer, now, timer->arg); newTime = (*timer->callback) (timer, now, timer->arg);
if (newTime) if (newTime)
TimerSet(timer, 0, newTime, timer->callback, timer->arg); TimerSet(timer, 0, newTime, timer->callback, timer->arg);
OsReleaseSignals();
} }
OsTimerPtr OsTimerPtr
@ -418,6 +422,7 @@ TimerSet(OsTimerPtr timer, int flags, CARD32 millis,
return NULL; return NULL;
} }
else { else {
OsBlockSignals();
for (prev = &timers; *prev; prev = &(*prev)->next) { for (prev = &timers; *prev; prev = &(*prev)->next) {
if (*prev == timer) { if (*prev == timer) {
*prev = timer->next; *prev = timer->next;
@ -426,6 +431,7 @@ TimerSet(OsTimerPtr timer, int flags, CARD32 millis,
break; break;
} }
} }
OsReleaseSignals();
} }
if (!millis) if (!millis)
return timer; return timer;
@ -445,26 +451,32 @@ TimerSet(OsTimerPtr timer, int flags, CARD32 millis,
if (!millis) if (!millis)
return timer; return timer;
} }
OsBlockSignals();
for (prev = &timers; for (prev = &timers;
*prev && (int) ((*prev)->expires - millis) <= 0; *prev && (int) ((*prev)->expires - millis) <= 0;
prev = &(*prev)->next); prev = &(*prev)->next);
timer->next = *prev; timer->next = *prev;
*prev = timer; *prev = timer;
OsReleaseSignals();
return timer; return timer;
} }
Bool Bool
TimerForce(OsTimerPtr timer) TimerForce(OsTimerPtr timer)
{ {
int rc = FALSE;
OsTimerPtr *prev; OsTimerPtr *prev;
OsBlockSignals();
for (prev = &timers; *prev; prev = &(*prev)->next) { for (prev = &timers; *prev; prev = &(*prev)->next) {
if (*prev == timer) { if (*prev == timer) {
DoTimer(timer, GetTimeInMillis(), prev); DoTimer(timer, GetTimeInMillis(), prev);
return TRUE; rc = TRUE;
break;
} }
} }
return FALSE; OsReleaseSignals();
return rc;
} }
void void
@ -474,12 +486,14 @@ TimerCancel(OsTimerPtr timer)
if (!timer) if (!timer)
return; return;
OsBlockSignals();
for (prev = &timers; *prev; prev = &(*prev)->next) { for (prev = &timers; *prev; prev = &(*prev)->next) {
if (*prev == timer) { if (*prev == timer) {
*prev = timer->next; *prev = timer->next;
break; break;
} }
} }
OsReleaseSignals();
} }
void void