nvme: fix race condition between connected uevent and STARTED_ONCE flag

When a controller connects, nvme_start_ctrl() emits the
"NVME_EVENT=connected" uevent and sets the NVME_CTRL_STARTED_ONCE flag.
Currently, the uevent is emitted before the flag is set. This creates a
race condition for userspace tools (like udev rules) that might rely on
the "connected" event to configure other attributes.

Swap the order of operations in nvme_start_ctrl() so that the
NVME_CTRL_STARTED_ONCE flag is set before the uevent is sent. This
guarantees that the admin_timeout can already be changed when userspace
is notified.

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 1e7e42b43aa3f1ac1bf1575a9f9ac46b37fc7f94..c3032d6ad6b1e2770312ab360a1eda216c31f9fb 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -5045,8 +5045,8 @@ void nvme_start_ctrl(struct nvme_ctrl *ctrl)
                nvme_mpath_update(ctrl);
        }
 
-       nvme_change_uevent(ctrl, "NVME_EVENT=connected");
        set_bit(NVME_CTRL_STARTED_ONCE, &ctrl->flags);
+       nvme_change_uevent(ctrl, "NVME_EVENT=connected");
 }
 EXPORT_SYMBOL_GPL(nvme_start_ctrl);