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Subject[PATCH 08/10] workqueue: assign overflowed flushers's flush color when queued
Date
wq->work_color is unchanged between overflowed flusher queued on
->flusher_overflow and requeued on ->flusher_queue.

So we can assign overflowed flushers's flush color when they are queued
on ->flusher_overflow.

This patch makes the flusher's flush color more clear:
flusher's flush color is the work color of the WQ
when flush_workqueue() starts.

Remove an unneeded loop.

This patch doesn't make any functional difference.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/workqueue.c | 19 +++++++++----------
1 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index be407e1..f687893 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2613,11 +2613,11 @@ void flush_workqueue(struct workqueue_struct *wq)
*/
flush_color = wq->work_color;
next_color = work_next_color(wq->work_color);
+ this_flusher.flush_color = flush_color;

if (next_color != wq->flush_color) {
/* Color space is not full */
BUG_ON(!list_empty(&wq->flusher_overflow));
- this_flusher.flush_color = flush_color;

if (!wq->first_flusher) {
/* no flush in progress, become the first flusher */
@@ -2643,8 +2643,8 @@ void flush_workqueue(struct workqueue_struct *wq)
} else {
/*
* Oops, color space is full, wait on overflow queue.
- * The next flush completion will assign us
- * flush_color and transfer to flusher_queue.
+ * The next flush completion will start flush for us
+ * with freed flush color and transfer us to flusher_queue.
*/
list_add_tail(&this_flusher.list, &wq->flusher_overflow);
}
@@ -2684,15 +2684,14 @@ void flush_workqueue(struct workqueue_struct *wq)

/* one color has been freed, handle overflow queue */
if (!list_empty(&wq->flusher_overflow)) {
+ BUG_ON(list_first_entry(&wq->flusher_overflow,
+ struct wq_flusher,
+ list)->flush_color
+ != wq->work_color);
/*
- * Assign the same color to all overflowed
- * flushers, advance work_color and append to
- * flusher_queue. This is the start-to-wait
- * phase for these overflowed flushers.
+ * start flush with the freed color and append
+ * overflowed flushers to the flusher_queue.
*/
- list_for_each_entry(tmp, &wq->flusher_overflow, list)
- tmp->flush_color = wq->work_color;
-
list_splice_tail_init(&wq->flusher_overflow,
&wq->flusher_queue);
workqueue_start_flush(wq);
--
1.7.4.4


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