From d416c92c5d6229b33f37f0f75e52194081ccbcc4 Mon Sep 17 00:00:00 2001 From: huhai Date: Fri, 18 May 2018 08:32:30 -0600 Subject: [PATCH] blk-mq: clear hctx->dispatch_from when mappings change When the number of hardware queues is changed, the drivers will call blk_mq_update_nr_hw_queues() to remap hardware queues. This changes the ctx mappings, but the current code doesn't clear the ->dispatch_from hint. This can result in dispatch_from pointing to a ctx that isn't mapped to the hctx anymore. Fixes: b347689ffbca ("blk-mq-sched: improve dispatching from sw queue") Signed-off-by: huhai Reviewed-by: Ming Lei Moved the placement of the clearing to where we clear other items pertaining to the existing mapping, added Fixes line, and reworded the commit message. Signed-off-by: Jens Axboe --- block/blk-mq.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index 6c6aef44badd..4cbfd784e837 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2358,6 +2358,7 @@ static void blk_mq_map_swqueue(struct request_queue *q) queue_for_each_hw_ctx(q, hctx, i) { cpumask_clear(hctx->cpumask); hctx->nr_ctx = 0; + hctx->dispatch_from = NULL; } /*