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fix thread leak on timer_create(SIGEV_THREAD) failure

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After commit 5b74eed3b3 the timer thread
doesn't check whether timer_create() actually created the timer,
proceeding to wait for a signal that might never arrive.  We can't fix
this by simply checking for a negative timer_id after
pthread_barrier_wait() because we have no way to distinguish a timer
creation failure and a request to delete a timer with INT_MAX id if it
happens to arrive quickly (a variation of this bug existed before
5b74eed3b3, where the timer would be
leaked in this case).  So (ab)use cancel field of pthread_t instead.
This commit is contained in:
Alexey Izbyshev 2022-09-08 12:18:56 +03:00 • committed by Rich Felker
parent bf14ef193b
commit 3ad3fa962e
1 changed files with 5 additions and 1 deletions
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6
src/time/timer_create.c
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@ -43,6 +43,8 @@ static void *start(void *arg)
union sigval val = args->sev->sigev_value;
pthread_barrier_wait(&args->b);
if (self->cancel)
return 0;
for (;;) {
siginfo_t si;
while (sigwaitinfo(SIGTIMER_SET, &si) < 0);
@ -113,8 +115,10 @@ int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict
ksev.sigev_signo = SIGTIMER;
ksev.sigev_notify = SIGEV_THREAD_ID;
ksev.sigev_tid = td->tid;
if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0) {
timerid = -1;
td->cancel = 1;
}
td->timer_id = timerid;
pthread_barrier_wait(&args.b);
if (timerid < 0) return -1;