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Subject[PATCH AUTOSEL 4.20 60/77] nvme-rdma: fix timeout handler
Date
From: Sagi Grimberg <sagi@grimberg.me>

[ Upstream commit 4c174e6366746ae8d49f9cc409f728eebb7a9ac9 ]

Currently, we have several problems with the timeout
handler:
1. If we timeout on the controller establishment flow, we will hang
because we don't execute the error recovery (and we shouldn't because
the create_ctrl flow needs to fail and cleanup on its own)
2. We might also hang if we get a disconnet on a queue while the
controller is already deleting. This racy flow can cause the controller
disable/shutdown admin command to hang.

We cannot complete a timed out request from the timeout handler without
mutual exclusion from the teardown flow (e.g. nvme_rdma_error_recovery_work).
So we serialize it in the timeout handler and teardown io and admin
queues to guarantee that no one races with us from completing the
request.

Reported-by: Jaesoo Lee <jalee@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/rdma.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index ab6ec7295bf9..6e24b20304b5 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1679,18 +1679,28 @@ static enum blk_eh_timer_return
nvme_rdma_timeout(struct request *rq, bool reserved)
{
struct nvme_rdma_request *req = blk_mq_rq_to_pdu(rq);
+ struct nvme_rdma_queue *queue = req->queue;
+ struct nvme_rdma_ctrl *ctrl = queue->ctrl;

- dev_warn(req->queue->ctrl->ctrl.device,
- "I/O %d QID %d timeout, reset controller\n",
- rq->tag, nvme_rdma_queue_idx(req->queue));
+ dev_warn(ctrl->ctrl.device, "I/O %d QID %d timeout\n",
+ rq->tag, nvme_rdma_queue_idx(queue));

- /* queue error recovery */
- nvme_rdma_error_recovery(req->queue->ctrl);
+ if (ctrl->ctrl.state != NVME_CTRL_LIVE) {
+ /*
+ * Teardown immediately if controller times out while starting
+ * or we are already started error recovery. all outstanding
+ * requests are completed on shutdown, so we return BLK_EH_DONE.
+ */
+ flush_work(&ctrl->err_work);
+ nvme_rdma_teardown_io_queues(ctrl, false);
+ nvme_rdma_teardown_admin_queue(ctrl, false);
+ return BLK_EH_DONE;
+ }

- /* fail with DNR on cmd timeout */
- nvme_req(rq)->status = NVME_SC_ABORT_REQ | NVME_SC_DNR;
+ dev_warn(ctrl->ctrl.device, "starting error recovery\n");
+ nvme_rdma_error_recovery(ctrl);

- return BLK_EH_DONE;
+ return BLK_EH_RESET_TIMER;
}

static blk_status_t nvme_rdma_queue_rq(struct blk_mq_hw_ctx *hctx,
--
2.19.1
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