From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Sender: Tejun Heo From: Tejun Heo To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, oleg@redhat.com, peterz@infradead.org, kernel-team@fb.com, osandov@fb.com, linux-block@vger.kernel.org, hch@lst.de, Tejun Heo Subject: [PATCH 6/6] blk-mq: remove REQ_ATOM_STARTED Date: Tue, 12 Dec 2017 11:01:34 -0800 Message-Id: <20171212190134.535941-7-tj@kernel.org> In-Reply-To: <20171212190134.535941-1-tj@kernel.org> References: <20171212190134.535941-1-tj@kernel.org> List-ID: After the recent updates to use generation number and state based synchronization, we can easily replace REQ_ATOM_STARTED usages by adding an extra state to distinguish completed but not yet freed state. Add MQ_RQ_COMPLETE and replace REQ_ATOM_STARTED usages with blk_mq_rq_state() tests. REQ_ATOM_STARTED no longer has any users left and is removed. Signed-off-by: Tejun Heo --- block/blk-mq-debugfs.c | 4 +--- block/blk-mq.c | 39 ++++++++------------------------------- block/blk-mq.h | 1 + block/blk.h | 1 - 4 files changed, 10 insertions(+), 35 deletions(-) diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index b56a4f3..8adc837 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -271,7 +271,6 @@ static const char *const cmd_flag_name[] = { #define RQF_NAME(name) [ilog2((__force u32)RQF_##name)] = #name static const char *const rqf_name[] = { RQF_NAME(SORTED), - RQF_NAME(STARTED), RQF_NAME(QUEUED), RQF_NAME(SOFTBARRIER), RQF_NAME(FLUSH_SEQ), @@ -295,7 +294,6 @@ static const char *const rqf_name[] = { #define RQAF_NAME(name) [REQ_ATOM_##name] = #name static const char *const rqaf_name[] = { RQAF_NAME(COMPLETE), - RQAF_NAME(STARTED), RQAF_NAME(POLL_SLEPT), }; #undef RQAF_NAME @@ -409,7 +407,7 @@ static void hctx_show_busy_rq(struct request *rq, void *data, bool reserved) const struct show_busy_params *params = data; if (blk_mq_map_queue(rq->q, rq->mq_ctx->cpu) == params->hctx && - test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) + blk_mq_rq_state(rq) != MQ_RQ_IDLE) __blk_mq_debugfs_rq_show(params->m, list_entry_rq(&rq->queuelist)); } diff --git a/block/blk-mq.c b/block/blk-mq.c index 7269552..bf53132 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -482,7 +482,7 @@ void blk_mq_free_request(struct request *rq) if (blk_rq_rl(rq)) blk_put_rl(blk_rq_rl(rq)); - clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags); + blk_mq_rq_update_state(rq, MQ_RQ_IDLE); clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags); if (rq->tag != -1) blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag); @@ -530,7 +530,7 @@ static void __blk_mq_complete_request(struct request *rq) int cpu; WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT); - blk_mq_rq_update_state(rq, MQ_RQ_IDLE); + blk_mq_rq_update_state(rq, MQ_RQ_COMPLETE); if (rq->internal_tag != -1) blk_mq_sched_completed_request(rq); @@ -610,7 +610,7 @@ EXPORT_SYMBOL(blk_mq_complete_request); int blk_mq_request_started(struct request *rq) { - return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags); + return blk_mq_rq_state(rq) != MQ_RQ_IDLE; } EXPORT_SYMBOL_GPL(blk_mq_request_started); @@ -629,7 +629,6 @@ void blk_mq_start_request(struct request *rq) } WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE); - WARN_ON_ONCE(test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)); /* * Mark @rq in-flight which also advances the generation number, @@ -647,8 +646,6 @@ void blk_mq_start_request(struct request *rq) blk_add_timer(rq); write_seqcount_end(&rq->gstate_seq); - set_bit(REQ_ATOM_STARTED, &rq->atomic_flags); - if (q->dma_drain_size && blk_rq_bytes(rq)) { /* * Make sure space for the drain appears. We know we can do @@ -661,13 +658,9 @@ void blk_mq_start_request(struct request *rq) EXPORT_SYMBOL(blk_mq_start_request); /* - * When we reach here because queue is busy, REQ_ATOM_COMPLETE - * flag isn't set yet, so there may be race with timeout handler, - * but given rq->deadline is just set in .queue_rq() under - * this situation, the race won't be possible in reality because - * rq->timeout should be set as big enough to cover the window - * between blk_mq_start_request() called from .queue_rq() and - * clearing REQ_ATOM_STARTED here. + * When we reach here because queue is busy, it's safe to change the state + * to IDLE without checking @rq->aborted_gstate because we should still be + * holding the RCU read lock and thus protected against timeout. */ static void __blk_mq_requeue_request(struct request *rq) { @@ -679,7 +672,7 @@ static void __blk_mq_requeue_request(struct request *rq) wbt_requeue(q->rq_wb, &rq->issue_stat); blk_mq_sched_requeue_request(rq); - if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) { + if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) { blk_mq_rq_update_state(rq, MQ_RQ_IDLE); if (q->dma_drain_size && blk_rq_bytes(rq)) rq->nr_phys_segments--; @@ -786,18 +779,6 @@ static void blk_mq_rq_timed_out(struct request *req, bool reserved) const struct blk_mq_ops *ops = req->q->mq_ops; enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER; - /* - * We know that complete is set at this point. If STARTED isn't set - * anymore, then the request isn't active and the "timeout" should - * just be ignored. This can happen due to the bitflag ordering. - * Timeout first checks if STARTED is set, and if it is, assumes - * the request is active. But if we race with completion, then - * both flags will get cleared. So check here again, and ignore - * a timeout event with a request that isn't active. - */ - if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags)) - return; - if (ops->timeout) ret = ops->timeout(req, reserved); @@ -831,9 +812,6 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, unsigned long gstate, deadline; int start; - if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) - return; - /* read coherent snapshots of @rq->state_gen and @rq->deadline */ do { start = read_seqcount_begin(&rq->gstate_seq); @@ -2951,8 +2929,7 @@ static bool blk_mq_poll_hybrid_sleep(struct request_queue *q, hrtimer_init_sleeper(&hs, current); do { - if (test_bit(REQ_ATOM_STARTED, &rq->atomic_flags) && - blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT) + if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE) break; set_current_state(TASK_UNINTERRUPTIBLE); hrtimer_start_expires(&hs.timer, mode); diff --git a/block/blk-mq.h b/block/blk-mq.h index 1fa83fa..523cad0 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -34,6 +34,7 @@ struct blk_mq_ctx { enum mq_rq_state { MQ_RQ_IDLE = 0, MQ_RQ_IN_FLIGHT = 1, + MQ_RQ_COMPLETE = 2, MQ_RQ_STATE_BITS = 2, MQ_RQ_STATE_MASK = (1 << MQ_RQ_STATE_BITS) - 1, diff --git a/block/blk.h b/block/blk.h index 9cb2739..a68dbe3 100644 --- a/block/blk.h +++ b/block/blk.h @@ -124,7 +124,6 @@ void blk_account_io_done(struct request *req); */ enum rq_atomic_flags { REQ_ATOM_COMPLETE = 0, - REQ_ATOM_STARTED, REQ_ATOM_POLL_SLEPT, }; -- 2.9.5