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authorTejun Heo <tj@kernel.org>2014-09-13 04:14:30 +0900
committerTejun Heo <tj@kernel.org>2014-09-13 05:13:08 +0900
commite09c2c295468476a239d13324ce9042ec4de05eb (patch)
tree876826d0d4284d4cc02ff5f80b61f1e2b91cbba4 /include/linux/workqueue.h
parent7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff)
workqueue: apply __WQ_ORDERED to create_singlethread_workqueue()
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@kernel.org> Reported-by: Mike Anderson <mike.anderson@us.ibm.com> Cc: Oleg Nesterov <onestero@redhat.com> Cc: Gustavo Luiz Duarte <gduarte@redhat.com> Cc: Tomas Henzl <thenzl@redhat.com> Cc: stable@vger.kernel.org Fixes: 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues")
Diffstat (limited to 'include/linux/workqueue.h')
-rw-r--r--include/linux/workqueue.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index a0cc2e95ed1b..b996e6cde6bb 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -419,7 +419,7 @@ __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);