[PATCH 2/2] nvme-fc: fix race between error recovery and creating association

[Michael Liang]

There is a small race window between nvme-fc association creation and error
recovery. Fix this race condition by protecting accessing to controller
state and ASSOC_FAILED flag under nvme-fc controller lock.

Signed-off-by: Michael Liang <mliang at purestorage.com>
Reviewed-by: Caleb Sander <csander at purestorage.com>
---
 drivers/nvme/host/fc.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index ad9336343e01..1cd2bf82319a 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -2548,17 +2548,24 @@ nvme_fc_error_recovery(struct nvme_fc_ctrl *ctrl, char *errmsg)
 	 * the controller.  Abort any ios on the association and let the
 	 * create_association error path resolve things.
 	 */
-	if (ctrl->ctrl.state == NVME_CTRL_CONNECTING) {
-		__nvme_fc_abort_outstanding_ios(ctrl, true);
+	enum nvme_ctrl_state state;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl->lock, flags);
+	state = ctrl->ctrl.state;
+	if (state == NVME_CTRL_CONNECTING) {
 		set_bit(ASSOC_FAILED, &ctrl->flags);
+		spin_unlock_irqrestore(&ctrl->lock, flags);
+		__nvme_fc_abort_outstanding_ios(ctrl, true);
 		dev_warn(ctrl->ctrl.device,
 			"NVME-FC{%d}: transport error during (re)connect\n",
 			ctrl->cnum);
 		return;
 	}
+	spin_unlock_irqrestore(&ctrl->lock, flags);
 
 	/* Otherwise, only proceed if in LIVE state - e.g. on first error */
-	if (ctrl->ctrl.state != NVME_CTRL_LIVE)
+	if (state != NVME_CTRL_LIVE)
 		return;
 
 	dev_warn(ctrl->ctrl.device,
@@ -3172,12 +3179,16 @@ nvme_fc_create_association(struct nvme_fc_ctrl *ctrl)
 		else
 			ret = nvme_fc_recreate_io_queues(ctrl);
 	}
+
+	spin_lock_irqsave(&ctrl->lock, flags);
 	if (!ret && test_bit(ASSOC_FAILED, &ctrl->flags))
 		ret = -EIO;
-	if (ret)
+	if (ret) {
+		spin_unlock_irqrestore(&ctrl->lock, flags);
 		goto out_term_aen_ops;
-
+	}
 	changed = nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_LIVE);
+	spin_unlock_irqrestore(&ctrl->lock, flags);
 
 	ctrl->ctrl.nr_reconnects = 0;
 
-- 
2.34.1