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This commit backs out most of commit b4747286b1.  That change was added because sem_wait() would sometimes cause cancellation points inappropriated.  But with these recent changes, nxsem_wait() is used instead and it is not a cancellation point.

    In the OS, all calls to sem_wait() changed to nxsem_wait().  nxsem_wait() does not return errors via errno so each place where nxsem_wait() is now called must not examine the errno variable.

    In all OS functions (not libraries), change sem_wait() to nxsem_wait().  This will prevent the OS from creating bogus cancellation points and from modifying the per-task errno variable.

    sched/semaphore:  Add the function nxsem_wait().  This is a new internal OS interface.  It is functionally equivalent to sem_wait() except that (1) it is not a cancellation point, and (2) it does not set the per-thread errno value on return.
This commit is contained in:
Gregory Nutt
2017-10-04 15:22:27 -06:00
parent 42a0796615
commit 9568600ab1
307 changed files with 3421 additions and 2423 deletions
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mm/iob/iob_alloc_qentry.c
+6 -17
View File
@@ -1,7 +1,7 @@
/****************************************************************************
* mm/iob/iob_alloc_qentry.c
*
* Copyright (C) 2014, 2016 Gregory Nutt. All rights reserved.
* Copyright (C) 2014, 2016-2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@@ -130,11 +130,9 @@ static FAR struct iob_qentry_s *iob_allocwait_qentry(void)
* semaphore count will be incremented.
*/
ret = sem_wait(&g_qentry_sem);
ret = nxsem_wait(&g_qentry_sem);
if (ret < 0)
{
int errcode = get_errno();
/* EINTR is not an error! EINTR simply means that we were
* awakened by a signal and we should try again.
*
@@ -144,20 +142,11 @@ static FAR struct iob_qentry_s *iob_allocwait_qentry(void)
* the error should be returned.
*/
if (errcode == EINTR)
if (ret == -EINTR)
{
/* Force a success indication so that we will continue
* looping.
*/
/* Force a success indication so that we will continue looping. */
ret = 0;
}
else
{
/* Stop the loop and return a error */
DEBUGASSERT(errcode > 0);
ret = -errcode;
ret = OK;
}
}
else
@@ -256,7 +245,7 @@ FAR struct iob_qentry_s *iob_tryalloc_qentry(void)
g_iob_freeqlist = iobq->qe_flink;
/* Take a semaphore count. Note that we cannot do this in
* in the orthodox way by calling sem_wait() or sem_trywait()
* in the orthodox way by calling nxsem_wait() or sem_trywait()
* because this function may be called from an interrupt
* handler. Fortunately we know at at least one free buffer
* so a simple decrement is all that is needed.