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mm/: Heap semaphore logic needs to use nxsem_* interfaces when available, but the standard semaphores only when implementing a user-space heap. Not this does introduce and issue: the memory management functions them become cancellation points because of the use of sem_wait.

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This commit is contained in:
Gregory Nutt 2017-10-07 07:16:33 -06:00
parent 8ef1f519d6
commit 91537a7722
1 changed files with 40 additions and 5 deletions
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45
mm/mm_heap/mm_sem.c
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@ -50,6 +50,31 @@
* Pre-processor Definitions
****************************************************************************/
/* Internal nxsem_* interfaces are not available in the user space in
* PROTECTED and FLAT builds. In that context, the application semaphore
* interfaces must be used. The differences between the two sets of
* interfaces are: (1) the nxsem_* interfaces do not cause cancellation
* points and (2) they do not modify the errno variable.
*
* REVISIT: The fact that sem_wait() is a cancellation point is an issue
* and does cause a violation: It makes all of the memory management
* interfaces into cancellation points!
*/
#if defined(CONFIG_BUILD_FLAT) || defined(__KERNEL__)
# define SEM_INIT(s,p,c) nxsem_init(s,p,c)
# define SEM_WAIT(s) nxsem_wait(s)
# define SEM_TRYWAIT(s) nxsem_trywait(s)
# define SEM_POST(s) nxsem_post(s)
# define SEM_ERROR(r)
#else
# define SEM_INIT(s,p,c) sem_init(s,p,c)
# define SEM_WAIT(s) sem_wait(s)
# define SEM_TRYWAIT(s) sem_trywait(s)
# define SEM_POST(s) sem_post(s)
# define SEM_ERROR(r) (r) = -errno
#endif
/* Define the following to enable semaphore state monitoring */
//#define MONITOR_MM_SEMAPHORE 1
@ -88,7 +113,7 @@ void mm_seminitialize(FAR struct mm_heap_s *heap)
* private data sets).
*/
(void)nxsem_init(&heap->mm_semaphore, 0, 1);
(void)SEM_INIT(&heap->mm_semaphore, 0, 1);
heap->mm_holder = -1;
heap->mm_counts_held = 0;
@ -123,9 +148,10 @@ int mm_trysemaphore(FAR struct mm_heap_s *heap)
{
/* Try to take the semaphore (perhaps waiting) */
ret = nxsem_trywait(&heap->mm_semaphore);
ret = SEM_TRYWAIT(&heap->mm_semaphore);
if (ret < 0)
{
SEM_ERROR(ret);
return ret;
}
@ -167,13 +193,22 @@ void mm_takesemaphore(FAR struct mm_heap_s *heap)
mseminfo("PID=%d taking\n", my_pid);
do
{
ret = nxsem_wait(&heap->mm_semaphore);
ret = SEM_WAIT(&heap->mm_semaphore);
/* The only case that an error should occur here is if the wait
* was awakened by a signal.
*/
DEBUGASSERT(ret == OK || ret == -EINTR);
if (ret < 0)
{
#if defined(CONFIG_BUILD_FLAT) || defined(__KERNEL__)
DEBUGASSERT(ret == -EINTR);
#else
int errcode = errno;
DEBUGASSERT(errcode == EINTR);
ret = -errcode;
#endif
}
}
while (ret == -EINTR);
@ -225,6 +260,6 @@ void mm_givesemaphore(FAR struct mm_heap_s *heap)
heap->mm_holder = -1;
heap->mm_counts_held = 0;
ASSERT(nxsem_post(&heap->mm_semaphore) == 0);
DEBUGVERIFY(SEM_POST(&heap->mm_semaphore));
}
}