On 08/10/2019 05:18, Ming Lei wrote:
Before one CPU becomes offline, check if it is the last online CPU of hctx. If yes, mark this hctx as BLK_MQ_S_INTERNAL_STOPPED, meantime wait for completion of all in-flight IOs originated from this hctx. This way guarantees that there isn't any inflight IO before shutdowning the managed IRQ line. Cc: John Garry <john.garry@xxxxxxxxxx> Cc: Bart Van Assche <bvanassche@xxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Keith Busch <keith.busch@xxxxxxxxx>
Apart from nits, below, FWIW: Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- block/blk-mq-tag.c | 2 +- block/blk-mq-tag.h | 2 ++ block/blk-mq.c | 40 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 43 insertions(+), 1 deletion(-) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 008388e82b5c..31828b82552b 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -325,7 +325,7 @@ static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, * true to continue iterating tags, false to stop. * @priv: Will be passed as second argument to @fn. */ -static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, +void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, void *priv) { if (tags->nr_reserved_tags) diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index 61deab0b5a5a..321fd6f440e6 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -35,6 +35,8 @@ extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, void *priv); +void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, + busy_tag_iter_fn *fn, void *priv); static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt, struct blk_mq_hw_ctx *hctx) diff --git a/block/blk-mq.c b/block/blk-mq.c index a664f196782a..3384242202eb 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2225,8 +2225,46 @@ int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, return -ENOMEM; } +static bool blk_mq_count_inflight_rq(struct request *rq, void *data, + bool reserved) +{ + unsigned *count = data; + + if ((blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT))
nit: extra parentheses
+ (*count)++; + + return true; +} + +static unsigned blk_mq_tags_inflight_rqs(struct blk_mq_tags *tags) +{ + unsigned count = 0; + + blk_mq_all_tag_busy_iter(tags, blk_mq_count_inflight_rq, &count); + + return count; +} + +static void blk_mq_hctx_drain_inflight_rqs(struct blk_mq_hw_ctx *hctx) +{ + while (1) { + if (!blk_mq_tags_inflight_rqs(hctx->tags)) + break; + msleep(5); + } +} + static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node) { + struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node, + struct blk_mq_hw_ctx, cpuhp_online); +
nit: we could make this a little neater by using an intermediate variable for hctx->cpumask:
struct cpumask *cpumask = hctx->cpumask; if ((cpumask_next_and(-1, cpumask, cpu_online_mask) == cpu) && ...
+ if ((cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) == cpu) && + (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) >= + nr_cpu_ids)) { + set_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state); + blk_mq_hctx_drain_inflight_rqs(hctx); + } return 0; } @@ -2246,6 +2284,8 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) ctx = __blk_mq_get_ctx(hctx->queue, cpu); type = hctx->type; + clear_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state); + spin_lock(&ctx->lock); if (!list_empty(&ctx->rq_lists[type])) { list_splice_init(&ctx->rq_lists[type], &tmp);