From mboxrd@z Thu Jan 1 00:00:00 1970 From: axboe@fb.com (Jens Axboe) Date: Fri, 14 Nov 2014 09:48:36 -0700 Subject: [PATCH] NVMe: limit max completion iterations in nvme_process_cq() Message-ID: <20141114164836.GB12860@kernel.dk> This is an unbounded loop. If we have per-cpu queues this is usually not a problem, but if CPUs share a queue, then we could have some of them continually queueing IO and the loop could take forever to exit. Limit max iterations to the queue depth of the given completion queue, which seems like a nice number to use. Signed-off-by: Jens Axboe --- drivers/block/nvme-core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c index f2964dfcea6c..fc2fc53992cb 100644 --- a/drivers/block/nvme-core.c +++ b/drivers/block/nvme-core.c @@ -697,12 +697,13 @@ static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx, static int nvme_process_cq(struct nvme_queue *nvmeq) { + unsigned int max_iter = nvmeq->q_depth; u16 head, phase; head = nvmeq->cq_head; phase = nvmeq->cq_phase; - for (;;) { + while (max_iter--) { void *ctx; nvme_completion_fn fn; struct nvme_completion cqe = nvmeq->cqes[head]; -- 1.9.1 -- Jens Axboe