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Merge "Fix race condition in timer disarm/delete." into lmp-mr1-dev

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This commit is contained in:
Christopher Ferris
2014-10-22 19:43:44 +00:00
committed by Android (Google) Code Review
parent 702ab5b37e 0724132c32
commit 9b7b0d82eb
2 changed files with 97 additions and 18 deletions
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20
libc/bionic/posix_timers.cpp
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@@ -62,6 +62,7 @@ struct PosixTimer {
pthread_t callback_thread;
void (*callback)(sigval_t);
sigval_t callback_argument;
volatile bool armed;
};
static __kernel_timer_t to_kernel_timer_id(timer_t timer) {
@@ -83,7 +84,7 @@ static void* __timer_thread_start(void* arg) {
continue;
}
if (si.si_code == SI_TIMER) {
if (si.si_code == SI_TIMER && timer->armed) {
// This signal was sent because a timer fired, so call the callback.
timer->callback(timer->callback_argument);
} else if (si.si_code == SI_TKILL) {
@@ -95,6 +96,9 @@ static void* __timer_thread_start(void* arg) {
}
static void __timer_thread_stop(PosixTimer* timer) {
// Immediately mark the timer as disarmed so even if some events
// continue to happen, the callback won't be called.
timer->armed = false;
pthread_kill(timer->callback_thread, TIMER_SIGNAL);
}
@@ -121,6 +125,7 @@ int timer_create(clockid_t clock_id, sigevent* evp, timer_t* timer_id) {
// Otherwise, this must be SIGEV_THREAD timer...
timer->callback = evp->sigev_notify_function;
timer->callback_argument = evp->sigev_value;
timer->armed = false;
// Check arguments that the kernel doesn't care about but we do.
if (timer->callback == NULL) {
@@ -200,7 +205,18 @@ int timer_gettime(timer_t id, itimerspec* ts) {
// http://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_getoverrun.html
int timer_settime(timer_t id, int flags, const itimerspec* ts, itimerspec* ots) {
return __timer_settime(to_kernel_timer_id(id), flags, ts, ots);
PosixTimer* timer= reinterpret_cast<PosixTimer*>(id);
int rc = __timer_settime(timer->kernel_timer_id, flags, ts, ots);
if (rc == 0) {
// Mark the timer as either being armed or disarmed. This avoids the
// callback being called after the disarm for SIGEV_THREAD timers only.
if (ts->it_value.tv_sec != 0 || ts->it_value.tv_nsec != 0) {
timer->armed = true;
} else {
timer->armed = false;
}
}
return rc;
}
// http://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_getoverrun.html