linux-kernel - [PATCH 1/3] blk-mq: cleanup after blk_mq_init_rq

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Date:	Thu, 17 Jul 2014 14:39:09 -0500
From:	Robert Elliott <elliott@...com>
To:	axboe@...nel.dk, abhijit.mahajan@...gotech.com, kmo@...arainc.com,
	nagalakshmi.nandigama@...gotech.com, asamymuthupa@...ron.com,
	snitzer@...hat.com, JBottomley@...allels.com,
	relliott@...rdog.cce.hp.com, sreekanth.reddy@...gotech.com,
	praveen.krishnamoorthy@...gotech.com, agordeev@...hat.com,
	scameron@...rdog.cce.hp.com, tom.leiming@...il.com, elliott@...com,
	sbradshaw@...ron.com, hch@....de, m@...rling.me
Cc:	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: [PATCH 1/3] blk-mq: cleanup after blk_mq_init_rq_map failures

In blk-mq.c blk_mq_alloc_tag_set, if:
	set->tags = kmalloc_node()
succeeds, but one of the blk_mq_init_rq_map() calls fails,
	goto out_unwind;
needs to free set->tags so the caller is not obligated
to do so.  None of the current callers (null_blk,
virtio_blk, virtio_blk, or the forthcoming scsi-mq)
do so.

set->tags needs to be set to NULL after doing so,
so other tag cleanup logic doesn't try to free
a stale pointer later.  Also set it to NULL
in blk_mq_free_tag_set.

Tested with error injection on the forthcoming
scsi-mq + hpsa combination.

Signed-off-by: Robert Elliott <elliott@...com>
---
 block/blk-mq.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ad69ef6..4a24b97 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1996,6 +1996,8 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
 out_unwind:
 	while (--i >= 0)
 		blk_mq_free_rq_map(set, set->tags[i], i);
+	kfree(set->tags);
+	set->tags = NULL;
 out:
 	return -ENOMEM;
 }
@@ -2011,6 +2013,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
 	}
 
 	kfree(set->tags);
+	set->tags = NULL;
 }
 EXPORT_SYMBOL(blk_mq_free_tag_set);
 

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