On Sat, Aug 4, 2018 at 8:03 AM, Bart Van Assche <bart.vanassche@xxxxxxx> wrote:
> Serialize these operations because a later patch will add code into
> blk_pre_runtime_suspend() that should not run concurrently with queue
> freezing nor unfreezing.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> ---
> block/blk-core.c | 5 +++++
> block/blk-mq.c | 3 +++
> block/blk-pm.c | 44 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/blk-pm.h | 6 ++++++
> include/linux/blkdev.h | 5 +++++
> 5 files changed, 63 insertions(+)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 03cff7445dee..59382c758155 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -17,6 +17,7 @@
> #include <linux/bio.h>
> #include <linux/blkdev.h>
> #include <linux/blk-mq.h>
> +#include <linux/blk-pm.h>
> #include <linux/highmem.h>
> #include <linux/mm.h>
> #include <linux/kernel_stat.h>
> @@ -696,6 +697,7 @@ void blk_set_queue_dying(struct request_queue *q)
> * prevent I/O from crossing blk_queue_enter().
> */
> blk_freeze_queue_start(q);
> + blk_pm_runtime_unlock(q);
>
> if (q->mq_ops)
> blk_mq_wake_waiters(q);
> @@ -756,6 +758,7 @@ void blk_cleanup_queue(struct request_queue *q)
> * prevent that q->request_fn() gets invoked after draining finished.
> */
> blk_freeze_queue(q);
> + blk_pm_runtime_unlock(q);
> spin_lock_irq(lock);
> queue_flag_set(QUEUE_FLAG_DEAD, q);
> spin_unlock_irq(lock);
> @@ -1045,6 +1048,8 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id,
> #ifdef CONFIG_BLK_DEV_IO_TRACE
> mutex_init(&q->blk_trace_mutex);
> #endif
> + blk_pm_init(q);
> +
> mutex_init(&q->sysfs_lock);
> spin_lock_init(&q->__queue_lock);
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 8b23ae34d949..b1882a3a5216 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -9,6 +9,7 @@
> #include <linux/backing-dev.h>
> #include <linux/bio.h>
> #include <linux/blkdev.h>
> +#include <linux/blk-pm.h>
> #include <linux/kmemleak.h>
> #include <linux/mm.h>
> #include <linux/init.h>
> @@ -138,6 +139,7 @@ void blk_freeze_queue_start(struct request_queue *q)
> {
> int freeze_depth;
>
> + blk_pm_runtime_lock(q);
> freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
> if (freeze_depth == 1) {
> percpu_ref_kill(&q->q_usage_counter);
> @@ -201,6 +203,7 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
> percpu_ref_reinit(&q->q_usage_counter);
> wake_up_all(&q->mq_freeze_wq);
> }
> + blk_pm_runtime_unlock(q);
> }
>From user view, it isn't reasonable to prevent runtime suspend from happening
during queue freeze. The period can be a bit long, and it should be one perfect
opportunity to suspend device during the period since no any IO is possible.
Thanks,
Ming Lei
