linux-kernel - [PATCH 3.13 119/163] workqueue: apply __WQ_ORDERED to create_singlethread

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1412888588-26755-120-git-send-email-kamal@canonical.com>
Date:	Thu,  9 Oct 2014 14:02:24 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Tejun Heo <tj@...nel.org>, Oleg Nesterov <onestero@...hat.com>,
	Gustavo Luiz Duarte <gduarte@...hat.com>,
	Tomas Henzl <thenzl@...hat.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13 119/163] workqueue: apply __WQ_ORDERED to create_singlethread_workqueue()

3.13.11.9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tejun Heo <tj@...nel.org>

commit e09c2c295468476a239d13324ce9042ec4de05eb upstream.

create_singlethread_workqueue() is a compat interface for single
threaded workqueue which maps to ordered workqueue w/ rescuer in the
current implementation.  create_singlethread_workqueue() currently
implemented by invoking alloc_workqueue() w/ appropriate parameters.

8719dceae2f9 ("workqueue: reject adjusting max_active or applying
attrs to ordered workqueues") introduced __WQ_ORDERED to protect
ordered workqueues against dynamic attribute changes which can break
ordering guarantees but forgot to apply it to
create_singlethread_workqueue().  This in itself is okay as nobody
currently uses dynamic attribute change on workqueues created with
create_singlethread_workqueue().

However, 4c16bd327c ("workqueue: implement NUMA affinity for unbound
workqueues") broke singlethreaded guarantee for ordered workqueues
through allocating a separate pool_workqueue on each NUMA node by
default.  A later change 8a2b75384444 ("workqueue: fix ordered
workqueues in NUMA setups") fixed it by allocating only one global
pool_workqueue if __WQ_ORDERED is set.

Combined, the __WQ_ORDERED omission in create_singlethread_workqueue()
became critical breaking its single threadedness and ordering
guarantee.

Let's make create_singlethread_workqueue() wrap
alloc_ordered_workqueue() instead so that it inherits __WQ_ORDERED and
can implicitly track future ordered_workqueue changes.

v2: I missed that __WQ_ORDERED now protects against pwq splitting
    across NUMA nodes and incorrectly described the patch as a
    nice-to-have fix to protect against future dynamic attribute
    usages.  Oleg pointed out that this is actually a critical
    breakage due to 8a2b75384444 ("workqueue: fix ordered workqueues
    in NUMA setups").

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Mike Anderson <mike.anderson@...ibm.com>
Cc: Oleg Nesterov <onestero@...hat.com>
Cc: Gustavo Luiz Duarte <gduarte@...hat.com>
Cc: Tomas Henzl <thenzl@...hat.com>
Fixes: 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues")
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 include/linux/workqueue.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 594521b..eff358e 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -455,7 +455,7 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
 	alloc_workqueue("%s", WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, \
 			1, (name))
 #define create_singlethread_workqueue(name)				\
-	alloc_workqueue("%s", WQ_UNBOUND | WQ_MEM_RECLAIM, 1, (name))
+	alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM, name)

 extern void destroy_workqueue(struct workqueue_struct *wq);

-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/