Tyrel Datwyler a264cf5e81 scsi: ibmvfc: Fix command state accounting and stale response detection ... Prior to commit 1f4a4a1950 ("scsi: ibmvfc: Complete commands outside the host/queue lock") responses to commands were completed sequentially with the host lock held such that a command had a basic binary state of active or free. It was therefore a simple affair of ensuring the assocaiated ibmvfc_event to a VIOS response was valid by testing that it was not already free. The lock relexation work to complete commands outside the lock inadverdently made it a trinary command state such that a command is either in flight, received and being completed, or completed and now free. This breaks the stale command detection logic as a command may be still marked active and been placed on the delayed completion list when a second stale response for the same command arrives. This can lead to double completions and list corruption. This issue was exposed by a recent VIOS regression were a missing memory barrier could occasionally result in the ibmvfc client receiving a duplicate response for the same command. Fix the issue by introducing the atomic ibmvfc_event.active to track the trinary state of a command. The state is explicitly set to 1 when a command is successfully sent. The CRQ response handlers use atomic_dec_if_positive() to test for stale responses and correctly transition to the completion state when a active command is received. Finally, atomic_dec_and_test() is used to sanity check transistions when commands are freed as a result of a completion, or moved to the purge list as a result of error handling or adapter reset. Link: https://lore.kernel.org/r/20210716205220.1101150-1-tyreld@linux.ibm.com Fixes: 1f4a4a1950 ("scsi: ibmvfc: Complete commands outside the host/queue lock") Cc: stable@vger.kernel.org Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>		2021-07-29 21:58:35 -04:00
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Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
ibmvfc.c	scsi: ibmvfc: Fix command state accounting and stale response detection	2021-07-29 21:58:35 -04:00
ibmvfc.h	scsi: ibmvfc: Fix command state accounting and stale response detection	2021-07-29 21:58:35 -04:00
ibmvscsi.c	scsi: core: Introduce scsi_status_is_check_condition()	2021-05-31 22:48:21 -04:00
ibmvscsi.h	SCSI misc on 20190709	2019-07-11 15:14:01 -07:00