diff options
author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2013-02-06 18:04:53 -0800 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2013-02-06 18:04:53 -0800 |
commit | 4468a00fd9a274fe1b30c886370d662e4a439efb (patch) | |
tree | 6ead9c97eea5cdb16cfd7fca3b80d1b184949e3e /kernel | |
parent | 60c057bca22285efefbba033624763a778f243bf (diff) | |
download | lwn-4468a00fd9a274fe1b30c886370d662e4a439efb.tar.gz lwn-4468a00fd9a274fe1b30c886370d662e4a439efb.zip |
workqueue: make work->data point to pool after try_to_grab_pending()
We plan to use work->data pointing to cwq as the synchronization
invariant when determining whether a given work item is on a locked
pool or not, which requires work->data pointing to cwq only while the
work item is queued on the associated pool.
With delayed_work updated not to overload work->data for target
workqueue recording, the only case where we still have off-queue
work->data pointing to cwq is try_to_grab_pending() which doesn't
update work->data after stealing a queued work item. There's no
reason for try_to_grab_pending() to not update work->data to point to
the pool instead of cwq, like the normal execution does.
This patch adds set_work_pool_and_keep_pending() which makes
work->data point to pool instead of cwq but keeps the pending bit
unlike set_work_pool_and_clear_pending() (surprise!).
After this patch, it's guaranteed that only queued work items point to
cwqs.
This patch doesn't introduce any visible behavior change.
tj: Renamed the new helper function to match
set_work_pool_and_clear_pending() and rewrote the description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/workqueue.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 41a502ce3802..1a442c301ddb 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -556,6 +556,13 @@ static void set_work_cwq(struct work_struct *work, WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); } +static void set_work_pool_and_keep_pending(struct work_struct *work, + int pool_id) +{ + set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, + WORK_STRUCT_PENDING); +} + static void set_work_pool_and_clear_pending(struct work_struct *work, int pool_id) { @@ -1115,6 +1122,9 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, cwq_dec_nr_in_flight(get_work_cwq(work), get_work_color(work)); + /* work->data points to cwq iff queued, point to pool */ + set_work_pool_and_keep_pending(work, pool->id); + spin_unlock(&pool->lock); return 1; } |