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| author | Tejun Heo <tj@kernel.org> | 2014-09-13 04:14:30 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-05 14:54:12 -0700 |
| commit | 545608863572bfc5836d15635e336410d9c952f8 (patch) | |
| tree | 139c3abf9b859dfa63114b26a555a936c56c4ec0 /include | |
| parent | dc19e20cf4ebd23a11fabc48ad2f297d894ec857 (diff) | |
| download | lwn-545608863572bfc5836d15635e336410d9c952f8.tar.gz lwn-545608863572bfc5836d15635e336410d9c952f8.zip | |
workqueue: apply __WQ_ORDERED to create_singlethread_workqueue()
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@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>
Fixes: 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/workqueue.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 623488fdc1f5..ff28cf578d01 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -414,7 +414,7 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active, #define create_freezable_workqueue(name) \ alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1) #define create_singlethread_workqueue(name) \ - alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1) + alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM, name) extern void destroy_workqueue(struct workqueue_struct *wq); |