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

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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: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2021-10-07 13:27:56 -07:00 committed by Martin K. Petersen
parent 9131bff6a9
commit bf23e61903
4 changed files with 24 additions and 11 deletions
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17
drivers/scsi/scsi_error.c
View file

@ -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;

10
drivers/scsi/scsi_lib.c
View file

@ -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);

1
drivers/scsi/scsi_priv.h
View file

@ -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);

7
include/scsi/scsi_cmnd.h
View file

@ -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;