scsi: cxlflash: Fix context reference tracking on detach

Commit 888baf06 ("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: 888baf06 ("scsi: cxlflash: Add kref to context")
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Acked-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

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)