[PATCHv2 2/5] scsi: make eh_eflags persistent

Hannes Reinecke
2017-02-22T16:07:35Z

To detect if a failed command has been retried we must not
clear scmd->eh_eflags when EH finishes.
The flag should be persistent throughout the lifetime
of the command.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
Documentation/scsi/scsi_eh.txt | 14 +++++++-------
drivers/scsi/scsi_error.c | 4 ++--
include/scsi/scsi_eh.h | 1 +
3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/Documentation/scsi/scsi_eh.txt b/Documentation/scsi/scsi_eh.txt
index 37eca00..4edb9c1c 100644
--- a/Documentation/scsi/scsi_eh.txt
+++ b/Documentation/scsi/scsi_eh.txt
@@ -105,11 +105,14 @@ function

2. If the host supports asynchronous completion (as indicated by the
no_async_abort setting in the host template) scsi_abort_command()
- is invoked to schedule an asynchrous abort. If that fails
- Step #3 is taken.
+ is invoked to schedule an asynchrous abort.
+ Asynchronous abort are not invoked for commands which the
+ SCSI_EH_ABORT_SCHEDULED flag is set (this indicates that the command
+ already had been aborted once, and this is a retry which failed),
+ or when the EH deadline is expired. In these case Step #3 is taken.

- 2. scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD) is invoked for the
- command. See [1-3] for more information.
+ 3. scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD) is invoked for the
+ command. See [1-4] for more information.

[1-3] Asynchronous command aborts

@@ -263,7 +266,6 @@ scmd->allowed.

3. scmd recovered
ACTION: scsi_eh_finish_cmd() is invoked to EH-finish scmd
- - clear scmd->eh_eflags
- scsi_setup_cmd_retry()
- move from local eh_work_q to local eh_done_q
LOCKING: none
@@ -456,8 +458,6 @@ except for #1 must be implemented by eh_strategy_handler().

- shost->host_failed is zero.

- - Each scmd's eh_eflags field is cleared.
-
- Each scmd is in such a state that scsi_setup_cmd_retry() on the
scmd doesn't make any difference.

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 9d7bfbb..023f882 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -188,7 +188,6 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)
/*
* Retry after abort failed, escalate to next level.
*/
- scmd->eh_eflags &= ~SCSI_EH_ABORT_SCHEDULED;
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"previous abort failed\n"));
@@ -931,6 +930,7 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
ses->result = scmd->result;
ses->underflow = scmd->underflow;
ses->prot_op = scmd->prot_op;
+ ses->eh_eflags = scmd->eh_eflags;

scmd->prot_op = SCSI_PROT_NORMAL;
scmd->eh_eflags = 0;
@@ -994,6 +994,7 @@ void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
scmd->result = ses->result;
scmd->underflow = ses->underflow;
scmd->prot_op = ses->prot_op;
+ scmd->eh_eflags = ses->eh_eflags;
}
EXPORT_SYMBOL(scsi_eh_restore_cmnd);

@@ -1126,7 +1127,6 @@ static int scsi_eh_action(struct scsi_cmnd *scmd, int rtn)
*/
void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
{
- scmd->eh_eflags = 0;
list_move_tail(&scmd->eh_entry, done_q);
}
EXPORT_SYMBOL(scsi_eh_finish_cmd);
diff --git a/include/scsi/scsi_eh.h b/include/scsi/scsi_eh.h
index 98d366b..a25b328 100644
--- a/include/scsi/scsi_eh.h
+++ b/include/scsi/scsi_eh.h
@@ -31,6 +31,7 @@ extern int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
struct scsi_eh_save {
/* saved state */
int result;
+ int eh_eflags;
enum dma_data_direction data_direction;
unsigned underflow;
unsigned char cmd_len;
--
1.8.5.6