Fix a "thread.arena" mallctl bug.

Fix a variable reversal bug in mallctl("thread.arena", ...).

jemalloc/src/ctl.c

@@ -1114,8 +1114,8 @@ thread_arena_ctl(const size_t *mib, size_t miblen, void *oldp, size_t *oldlenp,
 	unsigned newind, oldind;
 
 	newind = oldind = choose_arena()->ind;
-	WRITE(oldind, unsigned);
-	READ(newind, unsigned);
+	WRITE(newind, unsigned);
+	READ(oldind, unsigned);
 	if (newind != oldind) {
 		arena_t *arena;
 

jemalloc/test/thread_arena.c

@@ -2,10 +2,13 @@
 #include <stdlib.h>
 #include <pthread.h>
 #include <string.h>
+#include <assert.h>
 
 #define	JEMALLOC_MANGLE
 #include "jemalloc_test.h"
 
+#define NTHREADS 10
+
 void *
 thread_start(void *arg)
 {
@@ -29,6 +32,15 @@ thread_start(void *arg)
 		return (void *)1;
 	}
 
+	size = sizeof(arena_ind);
+	if ((err = JEMALLOC_P(mallctl)("thread.arena", &arena_ind, &size, NULL,
+	    0))) {
+		fprintf(stderr, "%s(): Error in mallctl(): %s\n", __func__,
+		    strerror(err));
+		return (void *)1;
+	}
+	assert(arena_ind == main_arena_ind);
+
 	return (NULL);
 }
 
@@ -40,7 +52,8 @@ main(void)
 	unsigned arena_ind;
 	size_t size;
 	int err;
-	pthread_t thread;
+	pthread_t threads[NTHREADS];
+	unsigned i;
 
 	fprintf(stderr, "Test begin\n");
 
@@ -60,21 +73,18 @@ main(void)
 		goto RETURN;
 	}
 
-	if (pthread_create(&thread, NULL, thread_start, (void *)&arena_ind)
-	    != 0) {
-		fprintf(stderr, "%s(): Error in pthread_create()\n", __func__);
-		ret = 1;
-		goto RETURN;
+	for (i = 0; i < NTHREADS; i++) {
+		if (pthread_create(&threads[i], NULL, thread_start,
+		    (void *)&arena_ind) != 0) {
+			fprintf(stderr, "%s(): Error in pthread_create()\n",
+			    __func__);
+			ret = 1;
+			goto RETURN;
+		}
 	}
-	pthread_join(thread, (void *)&ret);
 
-	if (pthread_create(&thread, NULL, thread_start, (void *)&arena_ind)
-	    != 0) {
-		fprintf(stderr, "%s(): Error in pthread_create()\n", __func__);
-		ret = 1;
-		goto RETURN;
-	}
-	pthread_join(thread, (void *)&ret);
+	for (i = 0; i < NTHREADS; i++)
+		pthread_join(threads[i], (void *)&ret);
 
 RETURN:
 	fprintf(stderr, "Test end\n");