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Subject[PATCH] nvme-pci: ensure nvme_timeout complete before initializing procedure
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There could be a nvme_timeout running with nvme_dev_disable in
parallel. The requests held by timeout path cannot be canceled
by nvme_dev_disable. Consequently, the nvme_timeout maybe still
running after nvme_dev_disable completes. Then there could be a
race between nvme_dev_disable in nvme_timeout and initializing
procedure in nvme_reset_work.
nvme_timeout nvme_reset_work
if (RESETTING) nvme_dev_disable
nvme_dev_disable initializing

To fix it, ensure all the q->timeout_work complete before the
initializing procedure in nvme_reset_work. At the moment, all the
outstanding requests should have been handled by nvme_dev_disable
or nvme_timeout.
So introduce nvme_sync_queues which invokes blk_sync_queue. In
addition to this, add blk_mq_kick_requeue_list into nvme_start_queues
and nvme_kill_queues to avoid IO hang in requeue_list, because
blk_sync_queue will cancel the requeue_work.

Link: https://lkml.org/lkml/2018/1/19/68
Suggested-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
---
drivers/nvme/host/core.c | 20 ++++++++++++++++++--
drivers/nvme/host/nvme.h | 1 +
drivers/nvme/host/pci.c | 9 ++++++++-
3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 23b3e53..c2ea8adb 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3443,7 +3443,11 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
revalidate_disk(ns->disk);
blk_set_queue_dying(ns->queue);

- /* Forcibly unquiesce queues to avoid blocking dispatch */
+ /*
+ * Forcibly kick requeue and unquiesce queues to avoid blocking
+ * dispatch
+ */
+ blk_mq_kick_requeue_list(ns->queue);
blk_mq_unquiesce_queue(ns->queue);
}
mutex_unlock(&ctrl->namespaces_mutex);
@@ -3513,12 +3517,24 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
struct nvme_ns *ns;

mutex_lock(&ctrl->namespaces_mutex);
- list_for_each_entry(ns, &ctrl->namespaces, list)
+ list_for_each_entry(ns, &ctrl->namespaces, list) {
+ blk_mq_kick_requeue_list(ns->queue);
blk_mq_unquiesce_queue(ns->queue);
+ }
mutex_unlock(&ctrl->namespaces_mutex);
}
EXPORT_SYMBOL_GPL(nvme_start_queues);

+void nvme_sync_queues(struct nvme_ctrl *ctrl)
+{
+ struct nvme_ns *ns;
+
+ mutex_lock(&ctrl->namespaces_mutex);
+ list_for_each_entry(ns, &ctrl->namespaces, list)
+ blk_sync_queue(ns->queue);
+ mutex_unlock(&ctrl->namespaces_mutex);
+}
+EXPORT_SYMBOL_GPL(nvme_sync_queues);
int nvme_reinit_tagset(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set)
{
if (!ctrl->ops->reinit_request)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index a44eeca..01faea6 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -370,6 +370,7 @@ int nvme_sec_submit(void *data, u16 spsp, u8 secp, void *buffer, size_t len,
void nvme_complete_async_event(struct nvme_ctrl *ctrl, __le16 status,
union nvme_result *res);

+void nvme_sync_queues(struct nvme_ctrl *ctrl);
void nvme_stop_queues(struct nvme_ctrl *ctrl);
void nvme_start_queues(struct nvme_ctrl *ctrl);
void nvme_kill_queues(struct nvme_ctrl *ctrl);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index f5207bc..9ba7e55 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2318,8 +2318,15 @@ static void nvme_reset_work(struct work_struct *work)
* If we're called to reset a live controller first shut it down before
* moving on.
*/
- if (dev->ctrl.ctrl_config & NVME_CC_ENABLE)
+ if (dev->ctrl.ctrl_config & NVME_CC_ENABLE) {
nvme_dev_disable(dev, false);
+ /* nvme_timeout could run in parallel, consequently,
+ * nvme_dev_disable invoked by nvme_timeout could race with
+ * following initializing procedure. So add nvme_sync_queues
+ * here to ensure nvme_timeout to be completed.
+ */
+ nvme_sync_queues(&dev->ctrl);
+ }

/*
* Introduce RECONNECTING state from nvme-fc/rdma transports to mark the
--
2.7.4
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