samples/userspace/shared_mem: Fix SMP race

There was some unlocked initialization code in the "enc" thread that
would race with the "pt" and "ct" threads if another CPU was available
to run them (it was safe on UP because "enc" entered the queue first
and was cooperative, the others wouldn't run until it blocked).

Move it to main() and remove the enc_state guard variable which is no
longer doing anything.

Signed-off-by: Andy Ross <[email protected]>

samples/userspace/shared_mem/src/main.c

@@ -78,7 +78,6 @@ struct k_thread ct_thread;
 K_THREAD_STACK_DEFINE(ct_stack, STACKSIZE);
 
 _app_enc_d char encMSG[] = "ENC!\n";
-_app_enc_d int enc_state = 1;
 _app_enc_b char enc_pt[50];  /* Copy form shared pt */
 _app_enc_b char enc_ct[50]; /* Copy to shared ct */
 
@@ -104,6 +103,15 @@ void main(void)
 	struct k_mem_partition *dom0_parts[] = {&part0, &part1};
 	k_tid_t tPT, tENC, tCT;
 
+	fBUFIN = 0; /* clear flags */
+	fBUFOUT = 0;
+	calc_rev_wheel((BYTE *) &W1, (BYTE *)&W1R);
+	calc_rev_wheel((BYTE *) &W2, (BYTE *)&W2R);
+	calc_rev_wheel((BYTE *) &W3, (BYTE *)&W3R);
+	IW1 = 0;
+	IW2 = 0;
+	IW3 = 0;
+
 	k_thread_access_grant(k_current_get(), &allforone);
 
 	/*
@@ -169,17 +177,6 @@ void enc(void)
 {
 
 	int index, index_out;
-	if (enc_state == 1) {
-		fBUFIN = 0; /* clear flags */
-		fBUFOUT = 0;
-		calc_rev_wheel((BYTE *) &W1, (BYTE *)&W1R);
-		calc_rev_wheel((BYTE *) &W2, (BYTE *)&W2R);
-		calc_rev_wheel((BYTE *) &W3, (BYTE *)&W3R);
-		IW1 = 0;
-		IW2 = 0;
-		IW3 = 0;
-		enc_state = 0;
-	}
 
 	while (1) {
 		k_sem_take(&allforone, K_FOREVER);