tests: kernel: semaphore: fix mutual exclusion test issue

Mutual exclusion test assume that the excution order of two threads like
this:
    mutual_exclusion1 -> mutual_exclusion2 -> mutual_exclusion1 ...

but some times the excution order of two threads would be this:
    mutual_exclusion1 -> mutual_exclusion2 -> mutual_exclusion2 ...

This patch increase the loop cycle, add a variable 'tmp' to store the
value of 'critical_var' before operating it.

Signed-off-by: Huifeng Zhang <[email protected]>

Author: SgrrZhf

tests/kernel/semaphore/semaphore/src/main.c

@@ -181,35 +181,37 @@ void sem_take_multiple_high_prio_helper(void *p1, void *p2, void *p3)
 /* First function for mutual exclusion test */
 void sem_queue_mutual_exclusion1(void *p1, void *p2, void *p3)
 {
-	for (int i = 0; i < 5; i++) {
+	for (int i = 0; i < 10000; i++) {
 		expect_k_sem_take_nomsg(&mut_sem, K_FOREVER, 0);
 
 		/* in that function critical section makes critical var +1 */
+		uint32_t tmp = critical_var;
 		critical_var += 1;
 
 		/* Check that common value was not changed by another thread,
 		 * when semaphore is taken by current thread, and no other
 		 * thread can enter the critical section
 		 */
-		zassert_true(critical_var == 1, NULL);
+		zassert_true(critical_var == tmp + 1, NULL);
 		k_sem_give(&mut_sem);
 	}
 }
 
 /* Second function for mutual exclusion test */
 void sem_queue_mutual_exclusion2(void *p1, void *p2, void *p3)
 {
-	for (int i = 0; i < 5; i++) {
+	for (int i = 0; i < 10000; i++) {
 		expect_k_sem_take_nomsg(&mut_sem, K_FOREVER, 0);
 
 		/* in that function critical section makes critical var 0 */
+		uint32_t tmp = critical_var;
 		critical_var -= 1;
 
 		/* Check that common value was not changed by another thread,
 		 * when semaphore is taken by current thread, and no other
 		 * thread can enter the critical section
 		 */
-		zassert_true(critical_var == 0, NULL);
+		zassert_true(critical_var == tmp - 1, NULL);
 		k_sem_give(&mut_sem);
 	}
 }