fix some semaphore wait semantics (race condition deadlock and error checking)

diff --git a/src/thread/sem_timedwait.c b/src/thread/sem_timedwait.c
index e6c2495..ad3bf07 100644 (file)
--- a/src/thread/sem_timedwait.c
+++ b/src/thread/sem_timedwait.c
@@ -8,7 +8,12 @@ int sem_timedwait(sem_t *sem, const struct timespec *at)
        for (;;) {
                if (a_fetch_add(sem->__val, -1) > 0) return 0;
                val = a_fetch_add(sem->__val, 1)+1;
        for (;;) {
                if (a_fetch_add(sem->__val, -1) > 0) return 0;
                val = a_fetch_add(sem->__val, 1)+1;

+               if (val==1) __wake(sem->__val, 1, 0);

                CANCELPT_BEGIN;
                CANCELPT_BEGIN;

+               if (at && at->tv_nsec >= 1000000000UL) {
+                       errno = EINVAL;
+                       return -1;
+               }

                if (val <= 0 && __timedwait(sem->__val, val, CLOCK_REALTIME, at, 0) == ETIMEDOUT) {
                        errno = ETIMEDOUT;
                        return -1;
                if (val <= 0 && __timedwait(sem->__val, val, CLOCK_REALTIME, at, 0) == ETIMEDOUT) {
                        errno = ETIMEDOUT;
                        return -1;

diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index d0e928e..c5370c7 100644 (file)
--- a/src/thread/sem_trywait.c
+++ b/src/thread/sem_trywait.c
@@ -5,7 +5,8 @@ int sem_trywait(sem_t *sem)
 {
        int val = a_fetch_add(sem->__val, -1);
        if (val > 0) return 0;
 {
        int val = a_fetch_add(sem->__val, -1);
        if (val > 0) return 0;

-       a_inc(sem->__val);
+       if (!a_fetch_add(sem->__val, 1))
+               __wake(sem->__val, 1, 0);

        errno = EAGAIN;
        return -1;
 }
        errno = EAGAIN;
        return -1;
 }