Fix context switch when time slicing is off (FreeRTOS#568)

* Fix context switch when time slicing is off

When time slicing is off, context switch should only happen when a
task with priority higher than the currently executing one is unblocked.
Earlier the code was invoking a context switch even when a task with
priority equal the currently executing task was unblocked. This commit
fixes the code to only do a context switch when a higher priority
task is unblocked.

Signed-off-by: Gaurav Aggarwal <[email protected]>

Author: aggarg

tasks.c

@@ -4090,10 +4090,14 @@ BaseType_t xTaskIncrementTick( void )
                             #if ( configNUM_CORES == 1 )
                             {
                                 /* Preemption is on, but a context switch should
-                                 * only be performed if the unblocked task has a
-                                 * priority that is equal to or higher than the
-                                 * currently executing task. */
-                                if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )
+                                 * only be performed if the unblocked task's
+                                 * priority is higher than the currently executing
+                                 * task.
+                                 * The case of equal priority tasks sharing
+                                 * processing time (which happens when both
+                                 * preemption and time slicing are on) is
+                                 * handled below.*/
+                                if( pxTCB->uxPriority > pxCurrentTCB->uxPriority )
                                 {
                                     xSwitchRequired = pdTRUE;
                                 }