From bc32ec3503433fae4c737c7ffe6b3822ce98d5d8 Mon Sep 17 00:00:00 2001
From: David Goldblatt <davidgoldblatt@fb.com>
Date: Tue, 4 Apr 2017 15:12:24 -0700
Subject: [PATCH] Move arena-tracking atomics in jemalloc.c to C11-style

---
 include/jemalloc/internal/extent_inlines.h       |  2 +-
 include/jemalloc/internal/jemalloc_internal.h.in |  7 +++----
 src/jemalloc.c                                   | 14 ++++++++------
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/jemalloc/internal/extent_inlines.h b/include/jemalloc/internal/extent_inlines.h
index e6e447cf..f1b94776 100644
--- a/include/jemalloc/internal/extent_inlines.h
+++ b/include/jemalloc/internal/extent_inlines.h
@@ -63,7 +63,7 @@ extent_arena_get(const extent_t *extent) {
 		return NULL;
 	}
 	assert(arena_ind <= MALLOCX_ARENA_MAX);
-	return arenas[arena_ind];
+	return (arena_t *)atomic_load_p(&arenas[arena_ind], ATOMIC_ACQUIRE);
 }
 
 JEMALLOC_INLINE szind_t
diff --git a/include/jemalloc/internal/jemalloc_internal.h.in b/include/jemalloc/internal/jemalloc_internal.h.in
index 4255b639..04f91c07 100644
--- a/include/jemalloc/internal/jemalloc_internal.h.in
+++ b/include/jemalloc/internal/jemalloc_internal.h.in
@@ -469,7 +469,7 @@ extern unsigned	narenas_auto;
  * Arenas that are used to service external requests.  Not all elements of the
  * arenas array are necessarily used; arenas are created lazily as needed.
  */
-extern arena_t	*arenas[];
+extern atomic_p_t arenas[];
 
 /*
  * pind2sz_tab encodes the same information as could be computed by
@@ -909,10 +909,9 @@ arena_get(tsdn_t *tsdn, unsigned ind, bool init_if_missing) {
 
 	assert(ind <= MALLOCX_ARENA_MAX);
 
-	ret = arenas[ind];
+	ret = (arena_t *)atomic_load_p(&arenas[ind], ATOMIC_ACQUIRE);
 	if (unlikely(ret == NULL)) {
-		ret = (arena_t *)atomic_read_p((void **)&arenas[ind]);
-		if (init_if_missing && unlikely(ret == NULL)) {
+		if (init_if_missing) {
 			ret = arena_init(tsdn, ind,
 			    (extent_hooks_t *)&extent_hooks_default);
 		}
diff --git a/src/jemalloc.c b/src/jemalloc.c
index 7c8fe9c9..94ae030c 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -55,10 +55,12 @@ static malloc_mutex_t	arenas_lock;
  * arenas[0..narenas_auto) are used for automatic multiplexing of threads and
  * arenas.  arenas[narenas_auto..narenas_total) are only used if the application
  * takes some action to create them and allocate from them.
+ *
+ * Points to an arena_t.
  */
 JEMALLOC_ALIGNED(CACHELINE)
-arena_t			*arenas[MALLOCX_ARENA_MAX + 1];
-static unsigned		narenas_total; /* Use narenas_total_*(). */
+atomic_p_t		arenas[MALLOCX_ARENA_MAX + 1];
+static atomic_u_t	narenas_total; /* Use narenas_total_*(). */
 static arena_t		*a0; /* arenas[0]; read-only after initialization. */
 unsigned		narenas_auto; /* Read-only after initialization. */
 
@@ -363,22 +365,22 @@ bootstrap_free(void *ptr) {
 
 void
 arena_set(unsigned ind, arena_t *arena) {
-	atomic_write_p((void **)&arenas[ind], arena);
+	atomic_store_p(&arenas[ind], arena, ATOMIC_RELEASE);
 }
 
 static void
 narenas_total_set(unsigned narenas) {
-	atomic_write_u(&narenas_total, narenas);
+	atomic_store_u(&narenas_total, narenas, ATOMIC_RELEASE);
 }
 
 static void
 narenas_total_inc(void) {
-	atomic_add_u(&narenas_total, 1);
+	atomic_fetch_add_u(&narenas_total, 1, ATOMIC_RELEASE);
 }
 
 unsigned
 narenas_total_get(void) {
-	return atomic_read_u(&narenas_total);
+	return atomic_load_u(&narenas_total, ATOMIC_ACQUIRE);
 }
 
 /* Create a new arena and insert it into the arenas array at index ind. */