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Subject[PATCH AUTOSEL 4.19 110/123] nvme: flush namespace scanning work just before removing namespaces
Date
From: Sagi Grimberg <sagi@grimberg.me>

[ Upstream commit f6c8e432cb0479255322c5d0335b9f1699a0270c ]

nvme_stop_ctrl can be called also for reset flow and there is no need to
flush the scan_work as namespaces are not being removed. This can cause
deadlock in rdma, fc and loop drivers since nvme_stop_ctrl barriers
before controller teardown (and specifically I/O cancellation of the
scan_work itself) takes place, but the scan_work will be blocked anyways
so there is no need to flush it.

Instead, move scan_work flush to nvme_remove_namespaces() where it really
needs to flush.

Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed by: James Smart <jsmart2021@gmail.com>
Tested-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 0ba301f7e8b4..b7b2659e02fa 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3308,6 +3308,9 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
struct nvme_ns *ns, *next;
LIST_HEAD(ns_list);

+ /* prevent racing with ns scanning */
+ flush_work(&ctrl->scan_work);
+
/*
* The dead states indicates the controller was not gracefully
* disconnected. In that case, we won't be able to flush any data while
@@ -3463,7 +3466,6 @@ void nvme_stop_ctrl(struct nvme_ctrl *ctrl)
nvme_mpath_stop(ctrl);
nvme_stop_keep_alive(ctrl);
flush_work(&ctrl->async_event_work);
- flush_work(&ctrl->scan_work);
cancel_work_sync(&ctrl->fw_act_work);
if (ctrl->ops->stop_ctrl)
ctrl->ops->stop_ctrl(ctrl);
--
2.17.1
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