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Event Groups: snapshot xEventGroupSetBits returning value while in vTaskSuspendAll. Fixes uxEventBits dereference after event group deleted by higher priority thread.

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This commit is contained in:
Aleksandr Kutuzov 2024-09-10 19:43:23 +01:00
parent 310ace5dd0
commit 7c9b24b301
2 changed files with 11 additions and 11 deletions
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9
event_groups.c
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@ -551,7 +551,7 @@
ListItem_t * pxNext;
ListItem_t const * pxListEnd;
List_t const * pxList;
EventBits_t uxBitsToClear = 0, uxBitsWaitedFor, uxControlBits;
EventBits_t uxBitsToClear = 0, uxBitsWaitedFor, uxControlBits, uxReturnBits;
EventGroup_t * pxEventBits = xEventGroup;
BaseType_t xMatchFound = pdFALSE;
@ -635,12 +635,15 @@
/* Clear any bits that matched when the eventCLEAR_EVENTS_ON_EXIT_BIT
* bit was set in the control word. */
pxEventBits->uxEventBits &= ~uxBitsToClear;
/* Snapshot resulting bits */
uxReturnBits = pxEventBits->uxEventBits;
}
( void ) xTaskResumeAll();
traceRETURN_xEventGroupSetBits( pxEventBits->uxEventBits );
traceRETURN_xEventGroupSetBits( uxReturnBits );
return pxEventBits->uxEventBits;
return uxReturnBits;
}
/*-----------------------------------------------------------*/

13
include/event_groups.h
View file

@ -483,14 +483,11 @@ EventBits_t xEventGroupClearBits( EventGroupHandle_t xEventGroup,
* and bit 0 set uxBitsToSet to 0x09.
*
* @return The value of the event group at the time the call to
* xEventGroupSetBits() returns. There are two reasons why the returned value
* might have the bits specified by the uxBitsToSet parameter cleared. First,
* if setting a bit results in a task that was waiting for the bit leaving the
* blocked state then it is possible the bit will be cleared automatically
* (see the xClearBitOnExit parameter of xEventGroupWaitBits()). Second, any
* unblocked (or otherwise Ready state) task that has a priority above that of
* the task that called xEventGroupSetBits() will execute and may change the
* event group value before the call to xEventGroupSetBits() returns.
* xEventGroupSetBits() returns. Returned value might have the bits specified
* by the uxBitsToSet parameter cleared if setting a bit results in a task
* that was waiting for the bit leaving the blocked state then it is possible
* the bit will be cleared automatically (see the xClearBitOnExit parameter
* of xEventGroupWaitBits()).
*
* Example usage:
* @code{c}