From 287922eb0b186e2a5bf54fdd04b734c25c90035c Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 30 Oct 2015 20:57:30 +0800 Subject: [PATCH] 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: Christoph Hellwig Acked-by: Keith Busch Signed-off-by: Jens Axboe --- block/blk-core.c | 8 ++++++++ block/blk-mq.c | 11 ++++++++--- block/blk-timeout.c | 8 ++++++-- block/blk.h | 2 +- include/linux/blkdev.h | 1 + 5 files changed, 24 insertions(+), 6 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 5ec996036e16..7e01002dfdde 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -664,6 +664,13 @@ static void blk_queue_usage_counter_release(struct percpu_ref *ref) wake_up_all(&q->mq_freeze_wq); } +static void blk_rq_timed_out_timer(unsigned long data) +{ + struct request_queue *q = (struct request_queue *)data; + + kblockd_schedule_work(&q->timeout_work); +} + 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; diff --git a/block/blk-mq.c b/block/blk-mq.c index 93a4e1956915..9cb2894840ab 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -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)) + return; + 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) blk_mq_tag_idle(hctx); } } + blk_queue_exit(q); } /* @@ -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; diff --git a/block/blk-timeout.c b/block/blk-timeout.c index 3610af561748..dd4fdfbcb3dd 100644 --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -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)) + return; 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); + blk_queue_exit(q); } /** diff --git a/block/blk.h b/block/blk.h index c43926d3d74d..70e4aee9cdcb 100644 --- a/block/blk.h +++ b/block/blk.h @@ -93,7 +93,7 @@ static inline void blk_flush_integrity(void) } #endif -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 *); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e711f294934c..221dc3bac49f 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -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; -- 2.20.1