block: make queue flags non-atomic
We can save some atomic ops in the IO path, if we clearly define
the rules of how to modify the queue flags.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index e447799..d2f23ec 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -198,7 +198,8 @@
if (blk_queue_stopped(q))
return;
- if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
+ if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
+ __set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags);
mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
}
@@ -213,9 +214,10 @@
{
WARN_ON(!irqs_disabled());
- if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
+ if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
return 0;
+ queue_flag_clear(QUEUE_FLAG_PLUGGED, q);
del_timer(&q->unplug_timer);
return 1;
}
@@ -311,15 +313,16 @@
{
WARN_ON(!irqs_disabled());
- clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_STOPPED, q);
/*
* one level of recursion is ok and is much faster than kicking
* the unplug handling
*/
- if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ queue_flag_set(QUEUE_FLAG_REENTER, q);
q->request_fn(q);
- clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
blk_plug_device(q);
kblockd_schedule_work(&q->unplug_work);
@@ -344,7 +347,7 @@
void blk_stop_queue(struct request_queue *q)
{
blk_remove_plug(q);
- set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
+ queue_flag_set(QUEUE_FLAG_STOPPED, q);
}
EXPORT_SYMBOL(blk_stop_queue);
@@ -373,11 +376,8 @@
* blk_run_queue - run a single device queue
* @q: The queue to run
*/
-void blk_run_queue(struct request_queue *q)
+void __blk_run_queue(struct request_queue *q)
{
- unsigned long flags;
-
- spin_lock_irqsave(q->queue_lock, flags);
blk_remove_plug(q);
/*
@@ -385,15 +385,28 @@
* handling reinvoke the handler shortly if we already got there.
*/
if (!elv_queue_empty(q)) {
- if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ queue_flag_set(QUEUE_FLAG_REENTER, q);
q->request_fn(q);
- clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
blk_plug_device(q);
kblockd_schedule_work(&q->unplug_work);
}
}
+}
+EXPORT_SYMBOL(__blk_run_queue);
+/**
+ * blk_run_queue - run a single device queue
+ * @q: The queue to run
+ */
+void blk_run_queue(struct request_queue *q)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_run_queue);
@@ -406,7 +419,7 @@
void blk_cleanup_queue(struct request_queue *q)
{
mutex_lock(&q->sysfs_lock);
- set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
+ queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
mutex_unlock(&q->sysfs_lock);
if (q->elevator)