[COMMITTED] malloc: Update comment for list_lock
Commit Message
On 12/22/2015 09:16 PM, Carlos O'Donell wrote:
> On 12/22/2015 02:32 PM, Florian Weimer wrote:
>> On 12/21/2015 10:54 PM, Carlos O'Donell wrote:
>>
>>>> + 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. */
>>>
>>> This last sentence seems ambiguous to me. I assume you mean to say that
>>> at the point at which list_lock is acquired there are no other arena
>>> locks held, but that after list_lock is acquired, other arena locks may
>>> be acquired afterwards?
>>
>> That was my intent. Is this clearer?
>>
>> 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.
>>
>> I'm following Torvald's earlier guidance not to speak of “held” locks.
>
> Looks good to me.
Thanks, committed.
Florian
From 7962541a32eff5597bc4207e781cfac8d1bb0d87 Mon Sep 17 00:00:00 2001
Message-Id: <7962541a32eff5597bc4207e781cfac8d1bb0d87.1450888146.git.fweimer@redhat.com>
From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 23 Dec 2015 17:23:33 +0100
Subject: [PATCH] malloc: Update comment for list_lock
To: libc-alpha@sourceware.org
---
ChangeLog | 4 ++++
malloc/arena.c | 7 ++++---
2 files changed, 8 insertions(+), 3 deletions(-)
@@ -1,3 +1,7 @@
+2015-12-23 Florian Weimer <fweimer@redhat.com>
+
+ * malloc/arena.c (list_lock): Update comment.
+
2015-12-22 Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
* sysdeps/powerpc/hwcapinfo.c: Export symbol
@@ -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 = _LIBC_LOCK_INITIALIZER;
/* Mapped memory in non-main arenas (reliable only for NO_THREADS). */
--
2.4.3