From 435df62d65bd0697a83565a16fb54c180665bd32 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Mon, 9 Aug 2021 16:03:04 -0700 Subject: [PATCH] UPSTREAM: scsi: core: Introduce the scsi_cmd_to_rq() function 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 Bug: 204438323 (cherry picked from commit 51f3a478892873337c54068d1185bcd797000a52) Signed-off-by: Bart Van Assche Change-Id: Iba5551cbb5d80daaab10dbbdb302aac7892ea442 --- include/scsi/scsi_cmnd.h | 10 +++++++++- include/scsi/scsi_device.h | 16 +++++++++------- 2 files changed, 18 insertions(+), 8 deletions(-) diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index b6398c9d2c5c..e8389b00ee74 100644 --- 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. @@ -162,7 +168,9 @@ static inline void *scsi_cmd_priv(struct scsi_cmnd *cmd) /* make sure not to use it with passthrough commands */ static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd) { - return *(struct scsi_driver **)cmd->request->rq_disk->private_data; + struct request *rq = scsi_cmd_to_rq(cmd); + + return *(struct scsi_driver **)rq->rq_disk->private_data; } extern void scsi_finish_command(struct scsi_cmnd *cmd); diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 158423bcdde9..a463f14c26b9 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -271,13 +271,15 @@ sdev_prefix_printk(const char *, const struct scsi_device *, const char *, __printf(3, 4) void scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...); -#define scmd_dbg(scmd, fmt, a...) \ - do { \ - if ((scmd)->request->rq_disk) \ - sdev_dbg((scmd)->device, "[%s] " fmt, \ - (scmd)->request->rq_disk->disk_name, ##a);\ - else \ - sdev_dbg((scmd)->device, fmt, ##a); \ +#define scmd_dbg(scmd, fmt, a...) \ + do { \ + struct request *__rq = scsi_cmd_to_rq((scmd)); \ + \ + if (__rq->rq_disk) \ + sdev_dbg((scmd)->device, "[%s] " fmt, \ + __rq->rq_disk->disk_name, ##a); \ + else \ + sdev_dbg((scmd)->device, fmt, ##a); \ } while (0) enum scsi_target_state {