Commit bf23e619 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: core: Use a structure member to track the SCSI command submitter 

Conditional statements are faster than indirect calls. Use a structure
member to track the SCSI command submitter such that later patches can call
scsi_done(scmd) instead of scmd->scsi_done(scmd).

The asymmetric behavior that scsi_send_eh_cmnd() sets the submission
context to the SCSI error handler and that it does not restore the
submission context to the SCSI core is retained.

Link: https://lore.kernel.org/r/20211007202923.2174984-2-bvanassche@acm.org


Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBenjamin Block <bblock@linux.ibm.com>
Reviewed-by: default avatarBean Huo <beanhuo@micron.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 9131bff6

drivers/scsi/scsi_error.c

+6 −11
Original line number Diff line number Diff line
@@ -50,8 +50,6 @@ 


#include <asm/unaligned.h>



static void scsi_eh_done(struct scsi_cmnd *scmd);



/*

 * These should *probably* be handled by the host itself.

 * Since it is allowed to sleep, it probably should.
@@ -520,7 +518,8 @@ enum scsi_disposition scsi_check_sense(struct scsi_cmnd *scmd) 
		/* handler does not care. Drop down to default handling */

	}



	if (scmd->cmnd[0] == TEST_UNIT_READY && scmd->scsi_done != scsi_eh_done)

	if (scmd->cmnd[0] == TEST_UNIT_READY &&

	    scmd->submitter != SUBMITTED_BY_SCSI_ERROR_HANDLER)

		/*

		 * nasty: for mid-layer issued TURs, we need to return the

		 * actual sense data without any recovery attempt.  For eh
@@ -782,7 +781,7 @@ static enum scsi_disposition scsi_eh_completed_normally(struct scsi_cmnd *scmd) 
 * scsi_eh_done - Completion function for error handling.

 * @scmd:	Cmd that is done.

 */

static void scsi_eh_done(struct scsi_cmnd *scmd)

void scsi_eh_done(struct scsi_cmnd *scmd)

{

	struct completion *eh_action;
@@ -1082,7 +1081,7 @@ static enum scsi_disposition scsi_send_eh_cmnd(struct scsi_cmnd *scmd, 
	shost->eh_action = &done;



	scsi_log_send(scmd);

	scmd->scsi_done = scsi_eh_done;

	scmd->submitter = SUBMITTED_BY_SCSI_ERROR_HANDLER;



	/*

	 * Lock sdev->state_mutex to avoid that scsi_device_quiesce() can
@@ -1109,6 +1108,7 @@ static enum scsi_disposition scsi_send_eh_cmnd(struct scsi_cmnd *scmd, 
	if (rtn) {

		if (timeleft > stall_for) {

			scsi_eh_restore_cmnd(scmd, &ses);



			timeleft -= stall_for;

			msleep(jiffies_to_msecs(stall_for));

			goto retry;
@@ -2338,11 +2338,6 @@ void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target) 
}

EXPORT_SYMBOL(scsi_report_device_reset);



static void

scsi_reset_provider_done_command(struct scsi_cmnd *scmd)

{

}



/**

 * scsi_ioctl_reset: explicitly reset a host/bus/target/device

 * @dev:	scsi_device to operate on
@@ -2379,7 +2374,7 @@ scsi_ioctl_reset(struct scsi_device *dev, int __user *arg) 
	scsi_init_command(dev, scmd);

	scmd->cmnd = scsi_req(rq)->cmd;



	scmd->scsi_done		= scsi_reset_provider_done_command;

	scmd->submitter = SUBMITTED_BY_SCSI_RESET_IOCTL;

	memset(&scmd->sdb, 0, sizeof(scmd->sdb));



	scmd->cmd_len			= 0;

drivers/scsi/scsi_lib.c

+10 −0
Original line number Diff line number Diff line
@@ -1577,6 +1577,15 @@ static blk_status_t scsi_prepare_cmd(struct request *req) 


static void scsi_mq_done(struct scsi_cmnd *cmd)

{

	switch (cmd->submitter) {

	case SUBMITTED_BY_BLOCK_LAYER:

		break;

	case SUBMITTED_BY_SCSI_ERROR_HANDLER:

		return scsi_eh_done(cmd);

	case SUBMITTED_BY_SCSI_RESET_IOCTL:

		return;

	}



	if (unlikely(blk_should_fake_timeout(scsi_cmd_to_rq(cmd)->q)))

		return;

	if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
@@ -1683,6 +1692,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, 


	scsi_set_resid(cmd, 0);

	memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);

	cmd->submitter = SUBMITTED_BY_BLOCK_LAYER;

	cmd->scsi_done = scsi_mq_done;



	blk_mq_start_request(req);

drivers/scsi/scsi_priv.h

+1 −0
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ void scsi_eh_ready_devs(struct Scsi_Host *shost, 
int scsi_eh_get_sense(struct list_head *work_q,

		      struct list_head *done_q);

int scsi_noretry_cmd(struct scsi_cmnd *scmd);

void scsi_eh_done(struct scsi_cmnd *scmd);



/* scsi_lib.c */

extern int scsi_maybe_unblock_host(struct scsi_device *sdev);

include/scsi/scsi_cmnd.h

+7 −0
Original line number Diff line number Diff line
@@ -64,6 +64,12 @@ struct scsi_pointer { 
#define SCMD_STATE_COMPLETE	0

#define SCMD_STATE_INFLIGHT	1



enum scsi_cmnd_submitter {

	SUBMITTED_BY_BLOCK_LAYER = 0,

	SUBMITTED_BY_SCSI_ERROR_HANDLER = 1,

	SUBMITTED_BY_SCSI_RESET_IOCTL = 2,

} __packed;



struct scsi_cmnd {

	struct scsi_request req;

	struct scsi_device *device;
@@ -89,6 +95,7 @@ struct scsi_cmnd { 
	unsigned char prot_op;

	unsigned char prot_type;

	unsigned char prot_flags;

	enum scsi_cmnd_submitter submitter;



	unsigned short cmd_len;

	enum dma_data_direction sc_data_direction;