Code review suggestions

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
This commit is contained in:
Gaurav Aggarwal 2024-08-05 10:22:06 +00:00
parent 32a5ae63c9
commit e1f990fa0c

25
tasks.c
View file

@ -3819,7 +3819,30 @@ void vTaskSuspendAll( void )
#if ( configNUMBER_OF_CORES == 1 )
{
/* A critical section is not required as the variable is of type
* BaseType_t. */
* BaseType_t. Each task maintains its own context, and a context switch
* cannot occur if the variable is non zero. So, as long as the writing
* from the register back into the memory is atomic, it is not a
* problem.
*
* Consider the following scenario, which starts with
* uxSchedulerSuspended at zero.
*
* 1. load uxSchedulerSuspended into register.
* 2. Now a context switch causes another task to run, and the other
* task uses the same variable. The other task will see the variable
* as zero because the variable has not yet been updated by the
* original task. Eventually the original task runs again. **That can
* only happen when uxSchedulerSuspended is once again zero**. When
* the original task runs again, the contents of the CPU registers
* are restored to exactly how they were when it was switched out -
* therefore the value it read into the register still matches the
* value of the uxSchedulerSuspended variable.
*
* 3. increment register.
* 4. store register into uxSchedulerSuspended. The value restored to
* uxSchedulerSuspended will be the correct value of 1, even though
* the variable was used by other tasks in the mean time.
*/
/* portSOFTWARE_BARRIER() is only implemented for emulated/simulated ports that
* do not otherwise exhibit real time behaviour. */