Skip to content

Feature/smp granular locks v4 #1154

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 12 commits into
base: main
Choose a base branch
from
Draft

Feature/smp granular locks v4 #1154

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
12 commits
Select commit Hold shift + click to select a range
11bc74c
refactor(freertos/smp): Move critical sections inside xTaskPriorityIn…
Dazza0 Jun 15, 2024
c4a723e
feat(freertos/smp): Allow vTaskPreemptionEnable() to be nested
Dazza0 Jun 15, 2024
6c5458c
feat(freertos/smp): Add granular locking port macros checks
Dazza0 Jun 15, 2024
8ceb94d
feat(granular_locks): Add granular locking functions
Dazza0 Jun 15, 2024
bf34180
change(freertos/smp): Update tasks.c locking
Dazza0 Jun 15, 2024
8b0eb06
change(freertos/smp): Update queue.c locking
Dazza0 Jun 15, 2024
463c2a9
change(freertos/smp): Update event_groups.c locking
Dazza0 Jun 15, 2024
bc4d600
change(freertos/smp): Update stream_buffer.c locking
Dazza0 Jun 15, 2024
c857a36
change(freertos/smp): Update timers.c locking
Dazza0 Jun 15, 2024
ec3c41e
feat(freertos/smp): Add Granular Locking V4 proposal documents
Dazza0 Jun 17, 2024
40a991d
feat(freertos-smp): Light Weight Preemption Disable Locks
sudeep-mohanty Aug 2, 2025
7df6202
fix(freertos-smp): Stop unconditional yielding in vTaskPreemptionEnable
sudeep-mohanty Aug 2, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
169 changes: 152 additions & 17 deletions event_groups.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -63,10 +63,48 @@
#if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) )
uint8_t ucStaticallyAllocated; /**< Set to pdTRUE if the event group is statically allocated to ensure no attempt is made to free the memory. */
#endif

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
portSPINLOCK_TYPE xTaskSpinlock;
portSPINLOCK_TYPE xISRSpinlock;
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */
} EventGroup_t;

/*-----------------------------------------------------------*/

/*
* Macros to mark the start and end of a critical code region.
*/
#if ( portUSING_GRANULAR_LOCKS == 1 )
#define event_groupsENTER_CRITICAL( pxEventBits ) taskDATA_GROUP_ENTER_CRITICAL( &pxEventBits->xTaskSpinlock, &pxEventBits->xISRSpinlock )
#define event_groupsENTER_CRITICAL_FROM_ISR( pxEventBits, puxSavedInterruptStatus ) taskDATA_GROUP_ENTER_CRITICAL_FROM_ISR( &pxEventBits->xISRSpinlock, puxSavedInterruptStatus )
#define event_groupsEXIT_CRITICAL( pxEventBits ) taskDATA_GROUP_EXIT_CRITICAL( &pxEventBits->xTaskSpinlock, &pxEventBits->xISRSpinlock )
#define event_groupsEXIT_CRITICAL_FROM_ISR( uxSavedInterruptStatus, pxEventBits ) taskDATA_GROUP_EXIT_CRITICAL_FROM_ISR( uxSavedInterruptStatus, &pxEventBits->xISRSpinlock )
#else /* #if ( portUSING_GRANULAR_LOCKS == 1 ) */
#define event_groupsENTER_CRITICAL( pxEventBits ) taskENTER_CRITICAL();
#define event_groupsENTER_CRITICAL_FROM_ISR( pxEventBits, puxSavedInterruptStatus ) do { *( puxSavedInterruptStatus ) = taskENTER_CRITICAL_FROM_ISR(); } while( 0 )
#define event_groupsEXIT_CRITICAL( pxEventBits ) taskEXIT_CRITICAL();
#define event_groupsEXIT_CRITICAL_FROM_ISR( uxSavedInterruptStatus, pxEventBits ) taskEXIT_CRITICAL_FROM_ISR( uxSavedInterruptStatus );
#endif /* #if ( portUSING_GRANULAR_LOCKS == 1 ) */

/*
* Locks an event group for tasks. Prevents other tasks from accessing the event group but allows
* ISRs to pend access to the event group. Caller cannot be preempted by other tasks
* after locking the event group, thus allowing the caller to execute non-deterministic
* operations.
*/
#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
static void prvLockEventGroupForTasks( EventGroup_t * pxEventBits ) PRIVILEGED_FUNCTION;
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

/*
* Unlocks an event group for tasks. Handles all pended access from ISRs, then reenables
* preemption for the caller.
*/
#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
static BaseType_t prvUnlockEventGroupForTasks( EventGroup_t * pxEventBits ) PRIVILEGED_FUNCTION;
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

/*
* Test the bits set in uxCurrentEventBits to see if the wait condition is met.
* The wait condition is defined by xWaitForAllBits. If xWaitForAllBits is
Expand All @@ -79,6 +117,25 @@
const EventBits_t uxBitsToWaitFor,
const BaseType_t xWaitForAllBits ) PRIVILEGED_FUNCTION;

/*-----------------------------------------------------------*/

/*
* Macros used to lock and unlock an event group. When a task locks an,
* event group, the task will have thread safe non-deterministic access to
* the event group.
* - Concurrent access from other tasks will be blocked by the xTaskSpinlock
* - Concurrent access from ISRs will be pended
*
* When the task unlocks the event group, all pended access attempts are handled.
*/
#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
#define event_groupsLOCK( pxEventBits ) prvLockEventGroupForTasks( pxEventBits )
#define event_groupsUNLOCK( pxEventBits ) prvUnlockEventGroupForTasks( pxEventBits );
#else /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */
#define event_groupsLOCK( pxEventBits ) vTaskSuspendAll()
#define event_groupsUNLOCK( pxEventBits ) xTaskResumeAll()
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

/*-----------------------------------------------------------*/

#if ( configSUPPORT_STATIC_ALLOCATION == 1 )
Expand Down Expand Up @@ -122,6 +179,13 @@
}
#endif /* configSUPPORT_DYNAMIC_ALLOCATION */

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
{
portINIT_SPINLOCK( &( pxEventBits->xTaskSpinlock ) );
portINIT_SPINLOCK( &( pxEventBits->xISRSpinlock ) );
}
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

traceEVENT_GROUP_CREATE( pxEventBits );
}
else
Expand Down Expand Up @@ -167,6 +231,13 @@
}
#endif /* configSUPPORT_STATIC_ALLOCATION */

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
{
portINIT_SPINLOCK( &( pxEventBits->xTaskSpinlock ) );
portINIT_SPINLOCK( &( pxEventBits->xISRSpinlock ) );
}
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

traceEVENT_GROUP_CREATE( pxEventBits );
}
else
Expand Down Expand Up @@ -202,7 +273,7 @@
}
#endif

vTaskSuspendAll();
event_groupsLOCK( pxEventBits );
{
uxOriginalBitValue = pxEventBits->uxEventBits;

Expand Down Expand Up @@ -245,7 +316,7 @@
}
}
}
xAlreadyYielded = xTaskResumeAll();
xAlreadyYielded = event_groupsUNLOCK( pxEventBits );

if( xTicksToWait != ( TickType_t ) 0 )
{
Expand All @@ -267,7 +338,7 @@
if( ( uxReturn & eventUNBLOCKED_DUE_TO_BIT_SET ) == ( EventBits_t ) 0 )
{
/* The task timed out, just return the current event bit value. */
taskENTER_CRITICAL();
event_groupsENTER_CRITICAL( pxEventBits );
{
uxReturn = pxEventBits->uxEventBits;

Expand All @@ -284,7 +355,7 @@
mtCOVERAGE_TEST_MARKER();
}
}
taskEXIT_CRITICAL();
event_groupsEXIT_CRITICAL( pxEventBits );

xTimeoutOccurred = pdTRUE;
}
Expand Down Expand Up @@ -333,7 +404,7 @@
}
#endif

vTaskSuspendAll();
event_groupsLOCK( pxEventBits );
{
const EventBits_t uxCurrentEventBits = pxEventBits->uxEventBits;

Expand Down Expand Up @@ -401,7 +472,7 @@
traceEVENT_GROUP_WAIT_BITS_BLOCK( xEventGroup, uxBitsToWaitFor );
}
}
xAlreadyYielded = xTaskResumeAll();
xAlreadyYielded = event_groupsUNLOCK( pxEventBits );

if( xTicksToWait != ( TickType_t ) 0 )
{
Expand All @@ -422,7 +493,7 @@

if( ( uxReturn & eventUNBLOCKED_DUE_TO_BIT_SET ) == ( EventBits_t ) 0 )
{
taskENTER_CRITICAL();
event_groupsENTER_CRITICAL( pxEventBits );
{
/* The task timed out, just return the current event bit value. */
uxReturn = pxEventBits->uxEventBits;
Expand All @@ -447,7 +518,7 @@

xTimeoutOccurred = pdTRUE;
}
taskEXIT_CRITICAL();
event_groupsEXIT_CRITICAL( pxEventBits );
}
else
{
Expand Down Expand Up @@ -482,7 +553,7 @@
configASSERT( xEventGroup );
configASSERT( ( uxBitsToClear & eventEVENT_BITS_CONTROL_BYTES ) == 0 );

taskENTER_CRITICAL();
event_groupsENTER_CRITICAL( pxEventBits );
{
traceEVENT_GROUP_CLEAR_BITS( xEventGroup, uxBitsToClear );

Expand All @@ -493,7 +564,7 @@
/* Clear the bits. */
pxEventBits->uxEventBits &= ~uxBitsToClear;
}
taskEXIT_CRITICAL();
event_groupsEXIT_CRITICAL( pxEventBits );

traceRETURN_xEventGroupClearBits( uxReturn );

Expand Down Expand Up @@ -524,19 +595,19 @@
EventBits_t xEventGroupGetBitsFromISR( EventGroupHandle_t xEventGroup )
{
UBaseType_t uxSavedInterruptStatus;
EventGroup_t const * const pxEventBits = xEventGroup;
EventGroup_t * const pxEventBits = xEventGroup;
EventBits_t uxReturn;

traceENTER_xEventGroupGetBitsFromISR( xEventGroup );

/* MISRA Ref 4.7.1 [Return value shall be checked] */
/* More details at: https://github.com/FreeRTOS/FreeRTOS-Kernel/blob/main/MISRA.md#dir-47 */
/* coverity[misra_c_2012_directive_4_7_violation] */
uxSavedInterruptStatus = taskENTER_CRITICAL_FROM_ISR();
event_groupsENTER_CRITICAL_FROM_ISR( pxEventBits, &uxSavedInterruptStatus );
{
uxReturn = pxEventBits->uxEventBits;
}
taskEXIT_CRITICAL_FROM_ISR( uxSavedInterruptStatus );
event_groupsEXIT_CRITICAL_FROM_ISR( uxSavedInterruptStatus, pxEventBits );

traceRETURN_xEventGroupGetBitsFromISR( uxReturn );

Expand Down Expand Up @@ -564,10 +635,17 @@

pxList = &( pxEventBits->xTasksWaitingForBits );
pxListEnd = listGET_END_MARKER( pxList );
vTaskSuspendAll();
event_groupsLOCK( pxEventBits );
{
traceEVENT_GROUP_SET_BITS( xEventGroup, uxBitsToSet );

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )

/* We are about to access the kernel data group non-deterministically,
* thus we suspend the kernel data group.*/
vTaskSuspendAll();
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

pxListItem = listGET_HEAD_ENTRY( pxList );

/* Set the bits. */
Expand Down Expand Up @@ -638,8 +716,12 @@

/* Snapshot resulting bits. */
uxReturnBits = pxEventBits->uxEventBits;

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
( void ) xTaskResumeAll();
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */
}
( void ) xTaskResumeAll();
( void ) event_groupsUNLOCK( pxEventBits );

traceRETURN_xEventGroupSetBits( uxReturnBits );

Expand All @@ -658,19 +740,30 @@

pxTasksWaitingForBits = &( pxEventBits->xTasksWaitingForBits );

vTaskSuspendAll();
event_groupsLOCK( pxEventBits );
{
traceEVENT_GROUP_DELETE( xEventGroup );

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )

/* We are about to access the kernel data group non-deterministically,
* thus we suspend the kernel data group.*/
vTaskSuspendAll();
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */

while( listCURRENT_LIST_LENGTH( pxTasksWaitingForBits ) > ( UBaseType_t ) 0 )
{
/* Unblock the task, returning 0 as the event list is being deleted
* and cannot therefore have any bits set. */
configASSERT( pxTasksWaitingForBits->xListEnd.pxNext != ( const ListItem_t * ) &( pxTasksWaitingForBits->xListEnd ) );
vTaskRemoveFromUnorderedEventList( pxTasksWaitingForBits->xListEnd.pxNext, eventUNBLOCKED_DUE_TO_BIT_SET );
}

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
( void ) xTaskResumeAll();
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */
}
( void ) xTaskResumeAll();
( void ) event_groupsUNLOCK( pxEventBits );

#if ( ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) && ( configSUPPORT_STATIC_ALLOCATION == 0 ) )
{
Expand Down Expand Up @@ -774,6 +867,48 @@
traceRETURN_vEventGroupClearBitsCallback();
}
/*-----------------------------------------------------------*/
#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
static void prvLockEventGroupForTasks( EventGroup_t * pxEventBits )
{
/* Disable preemption so that the current task cannot be preempted by another task */
vTaskPreemptionDisable( NULL );

/* Keep holding xTaskSpinlock to prevent tasks on other cores from accessing
* the event group while it is suspended. */
portGET_SPINLOCK( portGET_CORE_ID(), &( pxEventBits->xTaskSpinlock ) );
}
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */
/*-----------------------------------------------------------*/

#if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) )
static BaseType_t prvUnlockEventGroupForTasks( EventGroup_t * pxEventBits )
{
BaseType_t xReturn = pdFALSE;

/* Release the previously held task spinlock */
portRELEASE_SPINLOCK( portGET_CORE_ID(), &( pxEventBits->xTaskSpinlock ) );

/* Re-enable preemption */
vTaskPreemptionEnable( NULL );

/* Yield if preemption was re-enabled*/
if( xTaskUnlockCanYield() == pdTRUE )
Copy link
Member

@chinglee-iot chinglee-iot Aug 11, 2025 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

xTaskUnlockCanYield() should be called in critical section. We may create another internal API to return the already yielded information when preemption enabled.
For example,

Basetype_t xCurrentTaskPreemptionEnable( void );

{
taskYIELD_WITHIN_API();

/* Return true as the task was preempted */
xReturn = pdTRUE;
}
else
{
/* Return false as the task was not preempted */
xReturn = pdFALSE;
}

return xReturn;
}
#endif /* #if ( ( portUSING_GRANULAR_LOCKS == 1 ) && ( configNUMBER_OF_CORES > 1 ) ) */
/*-----------------------------------------------------------*/

static BaseType_t prvTestWaitCondition( const EventBits_t uxCurrentEventBits,
const EventBits_t uxBitsToWaitFor,
Expand Down
Loading