Commit 287922eb authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe

block: defer timeouts to a workqueue

Timer context is not very useful for drivers to perform any meaningful abort
action from.  So instead of calling the driver from this useless context
defer it to a workqueue as soon as possible.

Note that while a delayed_work item would seem the right thing here I didn't
dare to use it due to the magic in blk_add_timer that pokes deep into timer
internals.  But maybe this encourages Tejun to add a sensible API for that to
the workqueue API and we'll all be fine in the end :)

Contains a major update from Keith Bush:

"This patch removes synchronizing the timeout work so that the timer can
 start a freeze on its own queue. The timer enters the queue, so timer
 context can only start a freeze, but not wait for frozen."
Signed-off-by: default avatarChristoph Hellwig <>
Acked-by: default avatarKeith Busch <>
Signed-off-by: default avatarJens Axboe <>
parent 8c0b3915
......@@ -664,6 +664,13 @@ static void blk_queue_usage_counter_release(struct percpu_ref *ref)
static void blk_rq_timed_out_timer(unsigned long data)
struct request_queue *q = (struct request_queue *)data;
struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
struct request_queue *q;
......@@ -825,6 +832,7 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
goto fail;
INIT_WORK(&q->timeout_work, blk_timeout_work);
q->request_fn = rfn;
q->prep_rq_fn = NULL;
q->unprep_rq_fn = NULL;
......@@ -615,15 +615,19 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
static void blk_mq_rq_timer(unsigned long priv)
static void blk_mq_timeout_work(struct work_struct *work)
struct request_queue *q = (struct request_queue *)priv;
struct request_queue *q =
container_of(work, struct request_queue, timeout_work);
struct blk_mq_timeout_data data = {
.next = 0,
.next_set = 0,
int i;
if (blk_queue_enter(q, true))
blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
if (data.next_set) {
......@@ -638,6 +642,7 @@ static void blk_mq_rq_timer(unsigned long priv)
......@@ -2015,7 +2020,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
hctxs[i]->queue_num = i;
setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
q->nr_queues = nr_cpu_ids;
......@@ -127,13 +127,16 @@ static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout
void blk_rq_timed_out_timer(unsigned long data)
void blk_timeout_work(struct work_struct *work)
struct request_queue *q = (struct request_queue *) data;
struct request_queue *q =
container_of(work, struct request_queue, timeout_work);
unsigned long flags, next = 0;
struct request *rq, *tmp;
int next_set = 0;
if (blk_queue_enter(q, true))
spin_lock_irqsave(q->queue_lock, flags);
list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
......@@ -143,6 +146,7 @@ void blk_rq_timed_out_timer(unsigned long data)
mod_timer(&q->timeout, round_jiffies_up(next));
spin_unlock_irqrestore(q->queue_lock, flags);
......@@ -93,7 +93,7 @@ static inline void blk_flush_integrity(void)
void blk_rq_timed_out_timer(unsigned long data);
void blk_timeout_work(struct work_struct *work);
unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);
void blk_delete_timer(struct request *);
......@@ -407,6 +407,7 @@ struct request_queue {
unsigned int rq_timeout;
struct timer_list timeout;
struct work_struct timeout_work;
struct list_head timeout_list;
struct list_head icq_list;
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