We can detect whether a flusher is started by comparing its
flush_color VS wq->work_color.
We move all overflowed flusher to flusher_queue, and then we
start flush for them when there is freed color. we detect it
by the color of the last flusher of the flusher_queue.
This patch doesn't make any functional difference.
Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
---
kernel/workqueue.c | 39 +++++++++++++--------------------------
1 files changed, 13 insertions(+), 26 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f687893..d78fe08 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -252,7 +252,6 @@ struct workqueue_struct {
atomic_t nr_cwqs_to_flush[WORK_NR_COLORS];
struct wq_flusher *first_flusher; /* F: first flusher */
struct list_head flusher_queue; /* F: flush waiters */
- struct list_head flusher_overflow; /* F: flush overflow list */
mayday_mask_t mayday_mask; /* cpus requesting rescue */
struct worker *rescuer; /* I: rescue worker */
@@ -2600,7 +2599,7 @@ void flush_workqueue(struct workqueue_struct *wq)
.flush_color = -1,
.done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
};
- struct wq_flusher *next, *tmp;
+ struct wq_flusher *next, *tmp, *last;
int flush_color, next_color;
lock_map_acquire(&wq->lockdep_map);
@@ -2617,8 +2616,6 @@ void flush_workqueue(struct workqueue_struct *wq)
if (next_color != wq->flush_color) {
/* Color space is not full */
- BUG_ON(!list_empty(&wq->flusher_overflow));
-
if (!wq->first_flusher) {
/* no flush in progress, become the first flusher */
BUG_ON(wq->flush_color != flush_color);
@@ -2642,11 +2639,11 @@ void flush_workqueue(struct workqueue_struct *wq)
}
} else {
/*
- * Oops, color space is full, wait on overflow queue.
+ * Oops, color space is full, queue it without starting flush.
* The next flush completion will start flush for us
- * with freed flush color and transfer us to flusher_queue.
+ * with freed flush color.
*/
- list_add_tail(&this_flusher.list, &wq->flusher_overflow);
+ list_add_tail(&this_flusher.list, &wq->flusher_queue);
}
mutex_unlock(&wq->flush_mutex);
@@ -2676,27 +2673,9 @@ void flush_workqueue(struct workqueue_struct *wq)
complete(&next->done);
}
- BUG_ON(!list_empty(&wq->flusher_overflow) &&
- wq->flush_color != work_next_color(wq->work_color));
-
/* this flush_color is finished, advance by one */
wq->flush_color = work_next_color(wq->flush_color);
- /* 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);
- /*
- * start flush with the freed color and append
- * overflowed flushers to the flusher_queue.
- */
- list_splice_tail_init(&wq->flusher_overflow,
- &wq->flusher_queue);
- workqueue_start_flush(wq);
- }
-
if (list_empty(&wq->flusher_queue)) {
BUG_ON(wq->flush_color != wq->work_color);
wq->first_flusher = NULL;
@@ -2710,8 +2689,17 @@ void flush_workqueue(struct workqueue_struct *wq)
BUG_ON(wq->flush_color == wq->work_color);
BUG_ON(wq->flush_color != next->flush_color);
+ last = list_entry(wq->flusher_queue.prev, struct wq_flusher, list);
list_del_init(&next->list);
wq->first_flusher = next;
+
+ /* if have unstarted flushers appended, start flush for them */
+ if (last->flush_color == wq->work_color)
+ workqueue_start_flush(wq);
+
+ BUG_ON(work_next_color(last->flush_color) != wq->work_color);
+
+ /* arm new first flusher */
wq_dec_flusher_ref(wq, wq->flush_color);
out_unlock:
@@ -3221,7 +3209,6 @@ struct workqueue_struct *__alloc_workqueue_key(const char
*fmt,
for (color = 0; color < WORK_NR_COLORS; color++)
atomic_set(&wq->nr_cwqs_to_flush[color], 0);
INIT_LIST_HEAD(&wq->flusher_queue);
- INIT_LIST_HEAD(&wq->flusher_overflow);
lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
INIT_LIST_HEAD(&wq->list);
--
1.7.4.4
--
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