[PATCH AUTOSEL 5.4 207/330] nvme: Fix controller creation races with teardown flow

From: Sasha Levin
Date: Thu Sep 17 2020 - 23:02:36 EST

From: Israel Rukshin <israelr@xxxxxxxxxxxx>

[ Upstream commit ce1518139e6976cf19c133b555083354fdb629b8 ]

Calling nvme_sysfs_delete() when the controller is in the middle of
creation may cause several bugs. If the controller is in NEW state we
remove delete_controller file and don't delete the controller. The user
will not be able to use nvme disconnect command on that controller again,
although the controller may be active. Other bugs may happen if the
controller is in the middle of create_ctrl callback and
nvme_do_delete_ctrl() starts. For example, freeing I/O tagset at
nvme_do_delete_ctrl() before it was allocated at create_ctrl callback.

To fix all those races don't allow the user to delete the controller
before it was fully created.

Signed-off-by: Israel Rukshin <israelr@xxxxxxxxxxxx>
Reviewed-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/nvme/host/core.c | 5 +++++
drivers/nvme/host/nvme.h | 1 +
2 files changed, 6 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e51cc83969034..f01fe2d910b54 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3197,6 +3197,10 @@ static ssize_t nvme_sysfs_delete(struct device *dev,
struct nvme_ctrl *ctrl = dev_get_drvdata(dev);

+ /* Can't delete non-created controllers */
+ if (!ctrl->created)
+ return -EBUSY;
if (device_remove_file_self(dev, attr))
return count;
@@ -3992,6 +3996,7 @@ void nvme_start_ctrl(struct nvme_ctrl *ctrl)
+ ctrl->created = true;

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 80bfffa943ccd..7d57c42a641ca 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -253,6 +253,7 @@ struct nvme_ctrl {
struct nvme_command ka_cmd;
struct work_struct fw_act_work;
unsigned long events;
+ bool created;

/* asymmetric namespace access: */