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authorLai Jiangshan <laijs@cn.fujitsu.com>2013-02-06 18:04:53 -0800
committerTejun Heo <tj@kernel.org>2013-02-06 18:04:53 -0800
commit4468a00fd9a274fe1b30c886370d662e4a439efb (patch)
tree6ead9c97eea5cdb16cfd7fca3b80d1b184949e3e /kernel/workqueue.c
parent60c057bca22285efefbba033624763a778f243bf (diff)
downloadop-kernel-dev-4468a00fd9a274fe1b30c886370d662e4a439efb.zip
op-kernel-dev-4468a00fd9a274fe1b30c886370d662e4a439efb.tar.gz
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/workqueue.c')
-rw-r--r--kernel/workqueue.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 41a502c..1a442c3 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;
}
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