From: Keith Busch <keith.busch@intel.com>
Date: Thu, 18 Feb 2016 21:56:35 +0000 (-0700)
Subject: blk-mq: Fix NULL pointer updating nr_requests
X-Git-Tag: v4.6-rc1~97^2~6
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=e9137d4b93078b6a9965acfb18a2a2ad91cf8405;p=linux.git

blk-mq: Fix NULL pointer updating nr_requests

A h/w context's tags are freed if it was not assigned a CPU. Check if
the context has tags before updating the depth.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index f539a53d16c3..5667f59c277c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2336,6 +2336,8 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 
 	ret = 0;
 	queue_for_each_hw_ctx(q, hctx, i) {
+		if (!hctx->tags)
+			continue;
 		ret = blk_mq_tag_update_depth(hctx->tags, nr);
 		if (ret)
 			break;