[PATCH] scsi:target:tcmu: make sure dev blocked before resetting ring

[Guixin Liu <kanie@xxxxxxxxxxxxxxxxx>]

If dev is not blocked when resetting ring, then there could be new
commands coming in after resetting ring, this will make cmd ring broken,
because tcmu can not find tcmu_cmd when tcmu-runner handled these
newcome commands.

Signed-off-by: Guixin Liu <kanie@xxxxxxxxxxxxxxxxx>
---
 drivers/target/target_core_user.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 7b2a89a..548ad94 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -2333,7 +2333,7 @@ static void tcmu_block_dev(struct tcmu_dev *udev)
 	mutex_unlock(&udev->cmdr_lock);
 }
 
-static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
+static int tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
 {
 	struct tcmu_mailbox *mb;
 	struct tcmu_cmd *cmd;
@@ -2341,6 +2341,12 @@ static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
 
 	mutex_lock(&udev->cmdr_lock);
 
+	if (!test_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags)) {
+		pr_err("The dev should be blocked before resetting ring.\n");
+		mutex_unlock(&udev->cmdr_lock);
+		return -EINVAL;
+	}
+
 	xa_for_each(&udev->commands, i, cmd) {
 		pr_debug("removing cmd %u on dev %s from ring %s\n",
 			 cmd->cmd_id, udev->name,
@@ -2396,6 +2402,7 @@ static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
 	run_qfull_queue(udev, false);
 
 	mutex_unlock(&udev->cmdr_lock);
+	return 0;
 }
 
 enum {
@@ -2995,7 +3002,10 @@ static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
 		return -EINVAL;
 	}
 
-	tcmu_reset_ring(udev, val);
+	ret = tcmu_reset_ring(udev, val);
+	if (ret < 0)
+		return ret;
+
 	return count;
 }
 CONFIGFS_ATTR_WO(tcmu_, reset_ring);
-- 
1.8.3.1