[PATCH AUTOSEL 5.5 57/58] nvme: prevent warning triggered by nvme_stop_keep_alive

Sasha Levin
2020-02-23T02:34:21Z

From: Nigel Kirkland <nigel.kirkland@broadcom.com>

[ Upstream commit 97b2512ad000a409b4073dd1a71e4157d76675cb ]

Delayed keep alive work is queued on system workqueue and may be cancelled
via nvme_stop_keep_alive from nvme_reset_wq, nvme_fc_wq or nvme_wq.

Check_flush_dependency detects mismatched attributes between the work-queue
context used to cancel the keep alive work and system-wq. Specifically
system-wq does not have the WQ_MEM_RECLAIM flag, whereas the contexts used
to cancel keep alive work have WQ_MEM_RECLAIM flag.

Example warning:

workqueue: WQ_MEM_RECLAIM nvme-reset-wq:nvme_fc_reset_ctrl_work [nvme_fc]
is flushing !WQ_MEM_RECLAIM events:nvme_keep_alive_work [nvme_core]

To avoid the flags mismatch, delayed keep alive work is queued on nvme_wq.

However this creates a secondary concern where work and a request to cancel
that work may be in the same work queue - namely err_work in the rdma and
tcp transports, which will want to flush/cancel the keep alive work which
will now be on nvme_wq.

After reviewing the transports, it looks like err_work can be moved to
nvme_reset_wq. In fact that aligns them better with transition into
RESETTING and performing related reset work in nvme_reset_wq.

Change nvme-rdma and nvme-tcp to perform err_work in nvme_reset_wq.

Signed-off-by: Nigel Kirkland <nigel.kirkland@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/core.c | 10 +++++-----
drivers/nvme/host/rdma.c | 2 +-
drivers/nvme/host/tcp.c | 2 +-
3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 641c07347e8d8..ada59df642d29 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -66,8 +66,8 @@ MODULE_PARM_DESC(streams, "turn on support for Streams write directives");
* nvme_reset_wq - hosts nvme reset works
* nvme_delete_wq - hosts nvme delete works
*
- * nvme_wq will host works such are scan, aen handling, fw activation,
- * keep-alive error recovery, periodic reconnects etc. nvme_reset_wq
+ * nvme_wq will host works such as scan, aen handling, fw activation,
+ * keep-alive, periodic reconnects etc. nvme_reset_wq
* runs reset works which also flush works hosted on nvme_wq for
* serialization purposes. nvme_delete_wq host controller deletion
* works which flush reset works for serialization.
@@ -976,7 +976,7 @@ static void nvme_keep_alive_end_io(struct request *rq, blk_status_t status)
startka = true;
spin_unlock_irqrestore(&ctrl->lock, flags);
if (startka)
- schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
+ queue_delayed_work(nvme_wq, &ctrl->ka_work, ctrl->kato * HZ);
}

static int nvme_keep_alive(struct nvme_ctrl *ctrl)
@@ -1006,7 +1006,7 @@ static void nvme_keep_alive_work(struct work_struct *work)
dev_dbg(ctrl->device,
"reschedule traffic based keep-alive timer\n");
ctrl->comp_seen = false;
- schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
+ queue_delayed_work(nvme_wq, &ctrl->ka_work, ctrl->kato * HZ);
return;
}

@@ -1023,7 +1023,7 @@ static void nvme_start_keep_alive(struct nvme_ctrl *ctrl)
if (unlikely(ctrl->kato == 0))
return;

- schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
+ queue_delayed_work(nvme_wq, &ctrl->ka_work, ctrl->kato * HZ);
}

void nvme_stop_keep_alive(struct nvme_ctrl *ctrl)
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 2a47c6c5007e1..3e85c5cacefd2 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1088,7 +1088,7 @@ static void nvme_rdma_error_recovery(struct nvme_rdma_ctrl *ctrl)
if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RESETTING))
return;

- queue_work(nvme_wq, &ctrl->err_work);
+ queue_work(nvme_reset_wq, &ctrl->err_work);
}

static void nvme_rdma_wr_error(struct ib_cq *cq, struct ib_wc *wc,
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index f8fa5c5b79f17..49d4373b84eb3 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -422,7 +422,7 @@ static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl)
if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
return;

- queue_work(nvme_wq, &to_tcp_ctrl(ctrl)->err_work);
+ queue_work(nvme_reset_wq, &to_tcp_ctrl(ctrl)->err_work);
}

static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
--
2.20.1