malloc: Update comment for list_lock

(cherry picked from commit 7962541a32eff5597bc4207e781cfac8d1bb0d87)

2 files changed, 8 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index d97ce5a..fa02ac9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2016-04-13  Florian Weimer  <fweimer@redhat.com>
 
+	* malloc/arena.c (list_lock): Update comment.
+
+2016-04-13  Florian Weimer  <fweimer@redhat.com>
+
 	* malloc/tst-malloc-thread-exit.c: Include test-skeleton.c early.
 	(do_test): Limit the number of arenas, so that we can use fewer
 	outer threads.  Limit timeout to 3 seconds, in preparation for a
diff --git a/malloc/arena.c b/malloc/arena.c
index 463d31d..f03dcb2 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -85,9 +85,10 @@ static mstate free_list;
    _int_new_arena.  This suffers from data races; see the FIXME
    comments in _int_new_arena and reused_arena.
 
-   list_lock also prevents concurrent forks.  When list_lock is
-   acquired, no arena lock must be acquired, but it is permitted to
-   acquire arena locks after list_lock.  */
+   list_lock also prevents concurrent forks.  At the time list_lock is
+   acquired, no arena lock must have been acquired, but it is
+   permitted to acquire arena locks subsequently, while list_lock is
+   acquired.  */
 static mutex_t list_lock = MUTEX_INITIALIZER;
 
 /* Mapped memory in non-main arenas (reliable only for NO_THREADS). */