Fix a problem in pthread_trylock()

When CONFIG_PTHREAD_MUTEX_UNSAFE=y, the special return value
EAGAIN was not being detected due to differences in reporting of returned values.

diff --git a/os/kernel/pthread/pthread.h b/os/kernel/pthread/pthread.h
index 1793cf0..eda3bea 100644 (file)
--- a/os/kernel/pthread/pthread.h
+++ b/os/kernel/pthread/pthread.h
@@ -122,6 +122,9 @@ void pthread_destroyjoin(FAR struct task_group_s *group, FAR struct join_s *pjoi
 FAR struct join_s *pthread_findjoininfo(FAR struct task_group_s *group, pid_t pid);
 void pthread_release(FAR struct task_group_s *group);
 int pthread_takesemaphore(sem_t *sem, bool intr);
+#ifdef CONFIG_PTHREAD_MUTEX_UNSAFE
+int pthread_sem_trytake(sem_t *sem);
+#endif
 int pthread_givesemaphore(sem_t *sem);
 
 #ifndef CONFIG_PTHREAD_MUTEX_UNSAFE
@@ -131,7 +134,7 @@ int pthread_mutex_give(FAR struct pthread_mutex_s *mutex);
 void pthread_mutex_inconsistent(FAR struct pthread_tcb_s *tcb);
 #else
 #define pthread_mutex_take(m,i) pthread_takesemaphore(&(m)->sem,(i))
-#define pthread_mutex_trytake(m) sem_trywait(&(m)->sem)
+#define pthread_mutex_trytake(m) pthread_sem_trytake(&(m)->sem)
 #define pthread_mutex_give(m)   pthread_givesemaphore(&(m)->sem)
 #endif
 

diff --git a/os/kernel/pthread/pthread_initialize.c b/os/kernel/pthread/pthread_initialize.c
index 84336ce..a5faf40 100644 (file)
--- a/os/kernel/pthread/pthread_initialize.c
+++ b/os/kernel/pthread/pthread_initialize.c
@@ -157,6 +157,25 @@ int pthread_takesemaphore(sem_t *sem, bool intr)
        }
 }
 
+#ifdef CONFIG_PTHREAD_MUTEX_UNSAFE
+int pthread_sem_trytake(sem_t *sem)
+{
+       int ret = EINVAL;
+
+       /* Verify input parameters */
+
+       DEBUGASSERT(sem != NULL);
+       if (sem != NULL) {
+               /* Try to take the semaphore */
+
+               int status = sem_trywait(sem);
+               ret = status < 0 ? get_errno() : OK;
+       }
+
+       return ret;
+}
+#endif
+
 int pthread_givesemaphore(sem_t *sem)
 {
        /* Verify input parameters */