From a173db1e08b32e59b333f5936ff8a8f75b606882 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Mon, 9 Aug 2021 16:03:04 -0700 Subject: [PATCH] scsi: core: Introduce the scsi_cmd_to_rq() function [ 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 Cc: Hannes Reinecke Cc: Ming Lei Reviewed-by: Hannes Reinecke Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen Stable-dep-of: 19597cad64d6 ("scsi: qla2xxx: Fix system crash due to bad pointer access") Signed-off-by: Sasha Levin --- 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 4b7f14078..c2f3d3425 100755 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -150,6 +150,12 @@ struct scsi_cmnd { ANDROID_KABI_RESERVE(4); }; +/* 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.