test: Relocate posix mqueue receive buffer

For platforms that select Kconfig option CONFIG_KERNEL_COHERENCE,
the receive buffer used in mq_timedreceive() must not be on the
stack. This is because the k_msgq that underlies the POSIX mqueue
will attempt to perform a direct to buffer copy from the sender
when there is a waiting reader.

Fixes zephyrproject-rtos#60796

Signed-off-by: Peter Mitsis <[email protected]>

tests/posix/common/src/mqueue.c

@@ -21,8 +21,18 @@
 K_THREAD_STACK_ARRAY_DEFINE(stacks, N_THR, STACKSZ);
 
 char queue[16] = "server";
+
 char send_data[MESSAGE_SIZE] = "timed data send";
 
+/*
+ * For platforms that select CONFIG_KERNEL_COHERENCE, the receive buffer can
+ * not be on the stack as the k_msgq that underlies the mq_timedsend() will
+ * copy directly to the receiver's buffer when there is already a waiting
+ * receiver.
+ */
+
+char rec_data[MESSAGE_SIZE];
+
 void *sender_thread(void *p1)
 {
 	mqd_t mqd;
@@ -44,7 +54,6 @@ void *sender_thread(void *p1)
 void *receiver_thread(void *p1)
 {
 	mqd_t mqd;
-	char rec_data[MESSAGE_SIZE];
 	struct timespec curtime;
 
 	mqd = mq_open(queue, O_RDONLY);