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scsi: cxlflash: Fix context reference tracking on detach 

Commit 888baf069f ("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: 888baf069f ("scsi: cxlflash: Add kref to context")
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Acked-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Matthew R. Ochs 2016-09-02 15:40:41 -05:00 committed by Martin K. Petersen
parent f80132613d
commit c4a11827b7
1 changed files with 2 additions and 1 deletions
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3
drivers/scsi/cxlflash/superpipe.c
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@ -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)