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Posix: use thread local storage for critical section counter

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This commit allows non-FreeRTOS pthreads to safely call
vPortEnterCritical()/vPortExitCritical()

Non-FreeRTOS Task pthreads may need to enter a critical
section (for eg. printf()). In this case a single global
uxCriticalNesting is bogus since it is not copied and
restored on pthread scheduling.

GCC Thread-Local Storage to the rescue.

See https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html
This commit is contained in:
Thomas Pedersen 2021-02-15 11:07:26 -08:00
parent 1d4d16fd54
commit 3daf236d07
1 changed files with 1 additions and 15 deletions
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16
portable/ThirdParty/GCC/Posix/port.c vendored
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@ -94,7 +94,7 @@ static sigset_t xResumeSignals;
static sigset_t xAllSignals; static sigset_t xAllSignals;
static sigset_t xSchedulerOriginalSignalMask; static sigset_t xSchedulerOriginalSignalMask;
static pthread_t hMainThread = ( pthread_t )NULL; static pthread_t hMainThread = ( pthread_t )NULL;
static volatile portBASE_TYPE uxCriticalNesting; static volatile __thread portBASE_TYPE uxCriticalNesting = 0;
/*-----------------------------------------------------------*/ /*-----------------------------------------------------------*/
static portBASE_TYPE xSchedulerEnd = pdFALSE; static portBASE_TYPE xSchedulerEnd = pdFALSE;
@ -428,7 +428,6 @@ Thread_t *pxThread = pvParams;
prvSuspendSelf(pxThread); prvSuspendSelf(pxThread);
/* Resumed for the first time, unblocks all signals. */ /* Resumed for the first time, unblocks all signals. */
uxCriticalNesting = 0;
vPortEnableInterrupts(); vPortEnableInterrupts();
/* Call the task's entry point. */ /* Call the task's entry point. */
@ -448,27 +447,14 @@ Thread_t *pxThread = pvParams;
static void prvSwitchThread( Thread_t *pxThreadToResume, static void prvSwitchThread( Thread_t *pxThreadToResume,
Thread_t *pxThreadToSuspend ) Thread_t *pxThreadToSuspend )
{ {
BaseType_t uxSavedCriticalNesting;
if ( pxThreadToSuspend != pxThreadToResume ) if ( pxThreadToSuspend != pxThreadToResume )
{ {
/*
* Switch tasks.
*
* The critical section nesting is per-task, so save it on the
* stack of the current (suspending thread), restoring it when
* we switch back to this task.
*/
uxSavedCriticalNesting = uxCriticalNesting;
prvResumeThread( pxThreadToResume ); prvResumeThread( pxThreadToResume );
if ( pxThreadToSuspend->xDying ) if ( pxThreadToSuspend->xDying )
{ {
pthread_exit( NULL ); pthread_exit( NULL );
} }
prvSuspendSelf( pxThreadToSuspend ); prvSuspendSelf( pxThreadToSuspend );
uxCriticalNesting = uxSavedCriticalNesting;
} }
} }
/*-----------------------------------------------------------*/ /*-----------------------------------------------------------*/