From 8ef74e33b636a53a757a945d8ebc51d0986f0d81 Mon Sep 17 00:00:00 2001 From: Dixin Fan Date: Fri, 24 Feb 2023 16:18:47 -0600 Subject: Swapped out pthread_rwlock_xxlock(), which doesn't return if it can't obtain the lock, with pthread_rwlock_xxtrylock() followed by sched yield and error code return. The issue is sometimes a thread calling pthread_cond_init() or pthread_cond_destroy() can't acquire the lock when another thread is waiting on a condition variable notification via pthread_cond_timedwait(), and thus the thread calling pthread_cond_init() or pthread_cond_destroy() end up hanging indefinitely. --- src/libfaketime.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/src/libfaketime.c b/src/libfaketime.c index e8d0441..5fa8152 100644 --- a/src/libfaketime.c +++ b/src/libfaketime.c @@ -3602,9 +3602,9 @@ int pthread_cond_init_232(pthread_cond_t *restrict cond, const pthread_condattr_ struct pthread_cond_monotonic *e = (struct pthread_cond_monotonic*)malloc(sizeof(struct pthread_cond_monotonic)); e->ptr = cond; - if (pthread_rwlock_wrlock(&monotonic_conds_lock) != 0) { - fprintf(stderr,"can't acquire write monotonic_conds_lock\n"); - exit(-1); + if (pthread_rwlock_trywrlock(&monotonic_conds_lock) != 0) { + sched_yield(); + return EAGAIN; } HASH_ADD_PTR(monotonic_conds, ptr, e); pthread_rwlock_unlock(&monotonic_conds_lock); @@ -3617,9 +3617,9 @@ int pthread_cond_destroy_232(pthread_cond_t *cond) { struct pthread_cond_monotonic* e; - if (pthread_rwlock_wrlock(&monotonic_conds_lock) != 0) { - fprintf(stderr,"can't acquire write monotonic_conds_lock\n"); - exit(-1); + if (pthread_rwlock_trywrlock(&monotonic_conds_lock) != 0) { + sched_yield(); + return EBUSY; } HASH_FIND_PTR(monotonic_conds, &cond, e); if (e) { @@ -3701,9 +3701,9 @@ int pthread_cond_timedwait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, if (abstime != NULL) { - if (pthread_rwlock_rdlock(&monotonic_conds_lock) != 0) { - fprintf(stderr,"can't acquire read monotonic_conds_lock\n"); - exit(-1); + if (pthread_rwlock_tryrdlock(&monotonic_conds_lock) != 0) { + sched_yield(); + return EAGAIN; } HASH_FIND_PTR(monotonic_conds, &cond, e); pthread_rwlock_unlock(&monotonic_conds_lock); -- cgit v1.2.1