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blk-mq: fix dereference of rq->mq_ctx if allocation fails 

If __GFP_WAIT isn't set and we fail allocating, when we go
to drop the reference on the ctx, we will attempt to dereference
the NULL rq. Fix that.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jeff Moyer 2013-12-03 14:23:00 -07:00 committed by Jens Axboe
parent e345d767f6
commit 959a35f13e
1 changed files with 8 additions and 4 deletions
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12
block/blk-mq.c
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@ -202,10 +202,12 @@ static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
if (rq) {
blk_mq_rq_ctx_init(q, ctx, rq, rw);
break;
} else if (!(gfp & __GFP_WAIT))
break;
}
blk_mq_put_ctx(ctx);
if (!(gfp & __GFP_WAIT))
break;
__blk_mq_run_hw_queue(hctx);
blk_mq_wait_for_tags(hctx->tags);
} while (1);
@ -222,7 +224,8 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
return NULL;
rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
blk_mq_put_ctx(rq->mq_ctx);
if (rq)
blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
@ -235,7 +238,8 @@ struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
return NULL;
rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
blk_mq_put_ctx(rq->mq_ctx);
if (rq)
blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_reserved_request);