Allow setting extent hooks on uninitialized auto arenas.

Setting extent hooks can result in initializing an unused auto arena.  This is
useful to install extent hooks on auto arenas from the beginning.

1 files changed, 33 insertions, 12 deletions

diff --git a/src/ctl.c b/src/ctl.c
index 02610cf0..86c2837a 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -2251,20 +2251,41 @@ arena_i_extent_hooks_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
 
 	malloc_mutex_lock(tsd_tsdn(tsd), &ctl_mtx);
 	MIB_UNSIGNED(arena_ind, 1);
-	if (arena_ind < narenas_total_get() && (arena =
-	    arena_get(tsd_tsdn(tsd), arena_ind, false)) != NULL) {
-		if (newp != NULL) {
-			extent_hooks_t *old_extent_hooks;
-			extent_hooks_t *new_extent_hooks
-			    JEMALLOC_CC_SILENCE_INIT(NULL);
-			WRITE(new_extent_hooks, extent_hooks_t *);
-			old_extent_hooks = extent_hooks_set(tsd, arena,
-			    new_extent_hooks);
+	if (arena_ind < narenas_total_get()) {
+		extent_hooks_t *old_extent_hooks;
+		arena = arena_get(tsd_tsdn(tsd), arena_ind, false);
+		if (arena == NULL) {
+			if (arena_ind >= narenas_auto) {
+				ret = EFAULT;
+				goto label_return;
+			}
+			old_extent_hooks =
+			    (extent_hooks_t *)&extent_hooks_default;
 			READ(old_extent_hooks, extent_hooks_t *);
+			if (newp != NULL) {
+				/* Initialize a new arena as a side effect. */
+				extent_hooks_t *new_extent_hooks
+				    JEMALLOC_CC_SILENCE_INIT(NULL);
+				WRITE(new_extent_hooks, extent_hooks_t *);
+				arena = arena_init(tsd_tsdn(tsd), arena_ind,
+				    new_extent_hooks);
+				if (arena == NULL) {
+					ret = EFAULT;
+					goto label_return;
+				}
+			}
 		} else {
-			extent_hooks_t *old_extent_hooks =
-			    extent_hooks_get(arena);
-			READ(old_extent_hooks, extent_hooks_t *);
+			if (newp != NULL) {
+				extent_hooks_t *new_extent_hooks
+				    JEMALLOC_CC_SILENCE_INIT(NULL);
+				WRITE(new_extent_hooks, extent_hooks_t *);
+				old_extent_hooks = extent_hooks_set(tsd, arena,
+				    new_extent_hooks);
+				READ(old_extent_hooks, extent_hooks_t *);
+			} else {
+				old_extent_hooks = extent_hooks_get(arena);
+				READ(old_extent_hooks, extent_hooks_t *);
+			}
 		}
 	} else {
 		ret = EFAULT;