[PATCH 6/6] cxlflash: Fix context reference tracking on detach

[Uma Krishnan]

From: "Matthew R. Ochs" <mrochs at linux.vnet.ibm.com>

Commit 888baf069f49 ("scsi: cxlflash: Add kref to context") introduced a
kref to the context. In particular, the detach routine was updated to use
the kref services for managing the removal and destruction of a context.

As part of this change, the tracking mechanism internal to the detach
handler was refactored. This introduced a bug that can cause the tracking
state to be lost. This can lead to a situation where exclusive access to a
context is prematurely [and unknowingly] relinquished for the executing
thread.

To remedy, only update the tracking state when the kref operation indicates
the context was removed.

Fixes: 888baf069f49 ("scsi: cxlflash: Add kref to context")
Signed-off-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>
---
 drivers/scsi/cxlflash/superpipe.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
index c91fe6f..9636970 100644
--- a/drivers/scsi/cxlflash/superpipe.c
+++ b/drivers/scsi/cxlflash/superpipe.c
@@ -912,7 +912,8 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
 	 * Release the context reference and the sdev reference that
 	 * bound this LUN to the context.
 	 */
-	put_ctx = !kref_put(&ctxi->kref, remove_context);
+	if (kref_put(&ctxi->kref, remove_context))
+		put_ctx = false;
 	scsi_device_put(sdev);
 out:
 	if (put_ctx)
-- 
2.1.0