anchao commented on code in PR #14465:
URL: https://github.com/apache/nuttx/pull/14465#discussion_r1811799994
##########
sched/semaphore/sem_post.c:
##########
@@ -217,3 +214,60 @@ int nxsem_post(FAR sem_t *sem)
return OK;
}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxsem_post
+ *
+ * Description:
+ * When a kernel thread has finished with a semaphore, it will call
+ * nxsem_post(). This function unlocks the semaphore referenced by sem
+ * by performing the semaphore unlock operation on that semaphore.
+ *
+ * If the semaphore value resulting from this operation is positive, then
+ * no tasks were blocked waiting for the semaphore to become unlocked; the
+ * semaphore is simply incremented.
+ *
+ * If the value of the semaphore resulting from this operation is zero,
+ * then one of the tasks blocked waiting for the semaphore shall be
+ * allowed to return successfully from its call to nxsem_wait().
+ *
+ * Input Parameters:
+ * sem - Semaphore descriptor
+ *
+ * Returned Value:
+ * This is an internal OS interface and should not be used by applications.
+ * It follows the NuttX internal error return policy: Zero (OK) is
+ * returned on success. A negated errno value is returned on failure.
+ *
+ * Assumptions:
+ * This function may be called from an interrupt handler.
+ *
+ ****************************************************************************/
+
+int nxsem_post(FAR sem_t *sem)
+{
+ DEBUGASSERT(sem != NULL);
+
+ /* If this is a mutex, we can try to unlock the mutex in fast mode,
+ * else try to get it in slow mode.
+ */
+
+#if !defined(CONFIG_PRIORITY_INHERITANCE) && !defined(CONFIG_PRIORITY_PROTECT)
+ if (sem->flags & SEM_TYPE_MUTEX)
Review Comment:
why not move SEM_TYPE_MUTEX related logic inside mutex?
##########
sched/semaphore/sem_wait.c:
##########
@@ -224,6 +213,65 @@ int nxsem_wait(FAR sem_t *sem)
return ret;
}
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxsem_wait
+ *
+ * Description:
+ * This function attempts to lock the semaphore referenced by 'sem'. If
+ * the semaphore value is (<=) zero, then the calling task will not return
+ * until it successfully acquires the lock.
+ *
+ * This is an internal OS interface. It is functionally equivalent to
+ * sem_wait except that:
+ *
+ * - It is not a cancellation point, and
+ * - It does not modify the errno value.
+ *
+ * Input Parameters:
+ * sem - Semaphore descriptor.
+ *
+ * Returned Value:
+ * This is an internal OS interface and should not be used by applications.
+ * It follows the NuttX internal error return policy: Zero (OK) is
+ * returned on success. A negated errno value is returned on failure.
+ * Possible returned errors:
+ *
+ * - EINVAL: Invalid attempt to get the semaphore
+ * - EINTR: The wait was interrupted by the receipt of a signal.
+ *
+ ****************************************************************************/
+
+int nxsem_wait(FAR sem_t *sem)
+{
+ /* This API should not be called from interrupt handlers & idleloop */
+
+ DEBUGASSERT(sem != NULL && up_interrupt_context() == false);
+ DEBUGASSERT(!OSINIT_IDLELOOP() || !sched_idletask());
+
+ /* If this is a mutex, we can try to get the mutex in fast mode,
+ * else try to get it in slow mode.
+ */
+
+#if !defined(CONFIG_PRIORITY_INHERITANCE) && !defined(CONFIG_PRIORITY_PROTECT)
+ if (sem->flags & SEM_TYPE_MUTEX)
+ {
+ short old = 1;
+ if (atomic_compare_exchange_weak_explicit(NXSEM_COUNT(sem), &old, 0,
Review Comment:
ditto
##########
sched/semaphore/sem_post.c:
##########
@@ -217,3 +214,60 @@ int nxsem_post(FAR sem_t *sem)
return OK;
}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxsem_post
+ *
+ * Description:
+ * When a kernel thread has finished with a semaphore, it will call
+ * nxsem_post(). This function unlocks the semaphore referenced by sem
+ * by performing the semaphore unlock operation on that semaphore.
+ *
+ * If the semaphore value resulting from this operation is positive, then
+ * no tasks were blocked waiting for the semaphore to become unlocked; the
+ * semaphore is simply incremented.
+ *
+ * If the value of the semaphore resulting from this operation is zero,
+ * then one of the tasks blocked waiting for the semaphore shall be
+ * allowed to return successfully from its call to nxsem_wait().
+ *
+ * Input Parameters:
+ * sem - Semaphore descriptor
+ *
+ * Returned Value:
+ * This is an internal OS interface and should not be used by applications.
+ * It follows the NuttX internal error return policy: Zero (OK) is
+ * returned on success. A negated errno value is returned on failure.
+ *
+ * Assumptions:
+ * This function may be called from an interrupt handler.
+ *
+ ****************************************************************************/
+
+int nxsem_post(FAR sem_t *sem)
+{
+ DEBUGASSERT(sem != NULL);
+
+ /* If this is a mutex, we can try to unlock the mutex in fast mode,
+ * else try to get it in slow mode.
+ */
+
+#if !defined(CONFIG_PRIORITY_INHERITANCE) && !defined(CONFIG_PRIORITY_PROTECT)
+ if (sem->flags & SEM_TYPE_MUTEX)
+ {
+ short old = 0;
+ if (atomic_compare_exchange_weak_explicit(NXSEM_COUNT(sem), &old, 1,
Review Comment:
let us wrapper inline function named nxsem_post_fast
https://github.com/torvalds/linux/blob/master/kernel/locking/mutex.c#L177-L182
##########
sched/semaphore/sem_destroy.c:
##########
@@ -72,10 +74,18 @@ int nxsem_destroy(FAR sem_t *sem)
* leave the count unchanged but still return OK.
*/
- if (sem->semcount >= 0)
+ do
{
- sem->semcount = 1;
Review Comment:
I think this PR should be split to two, one is replace semaphore count type
to atomic, another one is fast mutex
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