Christoph Hellwig <hch@xxxxxx> writes:
> 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 :)
I don't see where the blk-mq timeout work is ever scheduled. You
removed the call to setup_timer for the mq case, so what causes the mq
timeout work to run? I must be missing something.
-Jeff
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> block/blk-core.c | 8 ++++++++
> block/blk-mq.c | 8 +++++---
> block/blk-timeout.c | 5 +++--
> block/blk.h | 2 +-
> include/linux/blkdev.h | 1 +
> 5 files changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 5131993b..1de0974 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 3ae09de..8354601 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -85,6 +85,7 @@ void blk_mq_freeze_queue_start(struct request_queue *q)
> freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
> if (freeze_depth == 1) {
> percpu_ref_kill(&q->q_usage_counter);
> + cancel_work_sync(&q->timeout_work);
> blk_mq_run_hw_queues(q, false);
> }
> }
> @@ -617,9 +618,10 @@ 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,
> @@ -2015,7 +2017,7 @@ 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 aa40aa9..aedd128 100644
> --- a/block/blk-timeout.c
> +++ b/block/blk-timeout.c
> @@ -127,9 +127,10 @@ 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;
> diff --git a/block/blk.h b/block/blk.h
> index da722eb..37b9165 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -95,7 +95,7 @@ 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 3fe27f8..9a8424a 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;
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