5.4-stable review patch. If anyone has any objections, please let me know.
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From: Bart Van Assche bvanassche@acm.org
[ Upstream commit 51f3a478892873337c54068d1185bcd797000a52 ]
The 'request' member of struct scsi_cmnd is superfluous. The struct request and struct scsi_cmnd data structures are adjacent and hence the request pointer can be derived easily from a scsi_cmnd pointer. Introduce a helper function that performs that conversion in a type-safe way. This patch is the first step towards removing the request member from struct scsi_cmnd. Making that change has the following advantages:
- This is a performance optimization since adding an offset to a pointer takes less time than dereferencing a pointer.
- struct scsi_cmnd becomes smaller.
Link: https://lore.kernel.org/r/20210809230355.8186-2-bvanassche@acm.org Cc: Christoph Hellwig hch@lst.de Cc: Hannes Reinecke hare@suse.de Cc: Ming Lei ming.lei@redhat.com Reviewed-by: Hannes Reinecke hare@suse.de Signed-off-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Stable-dep-of: 19597cad64d6 ("scsi: qla2xxx: Fix system crash due to bad pointer access") Signed-off-by: Sasha Levin sashal@kernel.org --- include/scsi/scsi_cmnd.h | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index 7738a055d9535..dafde3d764d03 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -143,6 +143,12 @@ struct scsi_cmnd { unsigned char tag; /* SCSI-II queued command tag */ };
+/* Variant of blk_mq_rq_from_pdu() that verifies the type of its argument. */ +static inline struct request *scsi_cmd_to_rq(struct scsi_cmnd *scmd) +{ + return blk_mq_rq_from_pdu(scmd); +} + /* * Return the driver private allocation behind the command. * Only works if cmd_size is set in the host template.