[PATCHv2 5/5] scsi: make asynchronous aborts mandatory

Hannes Reinecke
2017-02-22T16:07:34Z

There hasn't been any reports for HBAs where asynchronous abort
would not work, so we should make it mandatory and remove
the fallback.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
---
Documentation/scsi/scsi_eh.txt | 18 ++++------
drivers/scsi/scsi_error.c | 81 ++++--------------------------------------
drivers/scsi/scsi_lib.c | 2 +-
drivers/scsi/scsi_priv.h | 3 +-
include/scsi/scsi_host.h | 5 ---
5 files changed, 15 insertions(+), 94 deletions(-)

diff --git a/Documentation/scsi/scsi_eh.txt b/Documentation/scsi/scsi_eh.txt
index 4edb9c1c..11e447b 100644
--- a/Documentation/scsi/scsi_eh.txt
+++ b/Documentation/scsi/scsi_eh.txt
@@ -70,7 +70,7 @@ with the command.
scmd is requeued to blk queue.

- otherwise
- scsi_eh_scmd_add(scmd, 0) is invoked for the command. See
+ scsi_eh_scmd_add(scmd) is invoked for the command. See
[1-3] for details of this function.

@@ -103,9 +103,7 @@ function
eh_timed_out() callback did not handle the command.
Step #2 is taken.

- 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.
+ 2. scsi_abort_command() 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),
@@ -127,16 +125,13 @@ function

scmds enter EH via scsi_eh_scmd_add(), which does the following.

- 1. Turns on scmd->eh_eflags as requested. It's 0 for error
- completions and SCSI_EH_CANCEL_CMD for timeouts.
+ 1. Links scmd->eh_entry to shost->eh_cmd_q

- 2. Links scmd->eh_entry to shost->eh_cmd_q
+ 2. Sets SHOST_RECOVERY bit in shost->shost_state

- 3. Sets SHOST_RECOVERY bit in shost->shost_state
+ 3. Increments shost->host_failed

- 4. Increments shost->host_failed
-
- 5. Wakes up SCSI EH thread if shost->host_busy == shost->host_failed
+ 4. Wakes up SCSI EH thread if shost->host_busy == shost->host_failed

As can be seen above, once any scmd is added to shost->eh_cmd_q,
SHOST_RECOVERY shost_state bit is turned on. This prevents any new
@@ -252,7 +247,6 @@ scmd->allowed.

1. Error completion / time out
ACTION: scsi_eh_scmd_add() is invoked for scmd
- - set scmd->eh_eflags
- add scmd to shost->eh_cmd_q
- set SHOST_RECOVERY
- shost->host_failed++
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 381d642..aa6876d 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -162,7 +162,7 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)
}
}

- scsi_eh_scmd_add(scmd, 0);
+ scsi_eh_scmd_add(scmd);
}

/**
@@ -216,9 +216,8 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)
/**
* scsi_eh_scmd_add - add scsi cmd to error handling.
* @scmd: scmd to run eh on.
- * @eh_flag: optional SCSI_EH flag.
*/
-void scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
+void scsi_eh_scmd_add(struct scsi_cmnd *scmd)
{
struct Scsi_Host *shost = scmd->device->host;
unsigned long flags;
@@ -236,9 +235,6 @@ void scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
if (shost->eh_deadline != -1 && !shost->last_reset)
shost->last_reset = jiffies;

- if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED)
- eh_flag &= ~SCSI_EH_CANCEL_CMD;
- scmd->eh_eflags |= eh_flag;
list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
shost->host_failed++;
scsi_eh_wakeup(shost);
@@ -271,10 +267,9 @@ enum blk_eh_timer_return scsi_times_out(struct request *req)
rtn = host->hostt->eh_timed_out(scmd);

if (rtn == BLK_EH_NOT_HANDLED) {
- if (host->hostt->no_async_abort ||
- scsi_abort_command(scmd) != SUCCESS) {
+ if (scsi_abort_command(scmd) != SUCCESS) {
set_host_byte(scmd, DID_TIME_OUT);
- scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
+ scsi_eh_scmd_add(scmd);
}
}

@@ -327,7 +322,7 @@ static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
list_for_each_entry(scmd, work_q, eh_entry) {
if (scmd->device == sdev) {
++total_failures;
- if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
+ if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED)
++cmd_cancel;
else
++cmd_failed;
@@ -1141,8 +1136,7 @@ int scsi_eh_get_sense(struct list_head *work_q,
* should not get sense.
*/
list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
- if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
- (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) ||
+ if ((scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) ||
SCSI_SENSE_VALID(scmd))
continue;

@@ -1282,61 +1276,6 @@ static int scsi_eh_test_devices(struct list_head *cmd_list,
return list_empty(work_q);
}

-
-/**
- * scsi_eh_abort_cmds - abort pending commands.
- * @work_q: &list_head for pending commands.
- * @done_q: &list_head for processed commands.
- *
- * Decription:
- * Try and see whether or not it makes sense to try and abort the
- * running command. This only works out to be the case if we have one
- * command that has timed out. If the command simply failed, it makes
- * no sense to try and abort the command, since as far as the shost
- * adapter is concerned, it isn't running.
- */
-static int scsi_eh_abort_cmds(struct list_head *work_q,
- struct list_head *done_q)
-{
- struct scsi_cmnd *scmd, *next;
- LIST_HEAD(check_list);
- int rtn;
- struct Scsi_Host *shost;
-
- list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
- if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
- continue;
- shost = scmd->device->host;
- if (scsi_host_eh_past_deadline(shost)) {
- list_splice_init(&check_list, work_q);
- SCSI_LOG_ERROR_RECOVERY(3,
- scmd_printk(KERN_INFO, scmd,
- "%s: skip aborting cmd, past eh deadline\n",
- current->comm));
- return list_empty(work_q);
- }
- SCSI_LOG_ERROR_RECOVERY(3,
- scmd_printk(KERN_INFO, scmd,
- "%s: aborting cmd\n", current->comm));
- rtn = scsi_try_to_abort_cmd(shost->hostt, scmd);
- if (rtn == FAILED) {
- SCSI_LOG_ERROR_RECOVERY(3,
- scmd_printk(KERN_INFO, scmd,
- "%s: aborting cmd failed\n",
- current->comm));
- list_splice_init(&check_list, work_q);
- return list_empty(work_q);
- }
- scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
- if (rtn == FAST_IO_FAIL)
- scsi_eh_finish_cmd(scmd, done_q);
- else
- list_move_tail(&scmd->eh_entry, &check_list);
- }
-
- return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
-}
-
/**
* scsi_eh_try_stu - Send START_UNIT to device.
* @scmd: &scsi_cmnd to send START_UNIT
@@ -1679,11 +1618,6 @@ static void scsi_eh_offline_sdevs(struct list_head *work_q,
sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
"not ready after error recovery\n");
scsi_device_set_state(scmd->device, SDEV_OFFLINE);
- if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
- /*
- * FIXME: Handle lost cmds.
- */
- }
scsi_eh_finish_cmd(scmd, done_q);
}
return;
@@ -2127,8 +2061,7 @@ static void scsi_unjam_host(struct Scsi_Host *shost)
SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));

if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
- if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
- scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
+ scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);

spin_lock_irqsave(shost->host_lock, flags);
if (shost->eh_deadline != -1)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 03e9d40..a656d27 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1571,7 +1571,7 @@ static void scsi_softirq_done(struct request *rq)
scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
break;
default:
- scsi_eh_scmd_add(cmd, 0);
+ scsi_eh_scmd_add(cmd);
break;
}
}
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index e4e3483..827172e 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -18,7 +18,6 @@
/*
* Scsi Error Handler Flags
*/
-#define SCSI_EH_CANCEL_CMD 0x0001 /* Cancel this cmd */
#define SCSI_EH_ABORT_SCHEDULED 0x0002 /* Abort has been scheduled */

#define SCSI_SENSE_VALID(scmd) \
@@ -72,7 +71,7 @@ extern int scsi_dev_info_list_add_keyed(int compatible, char *vendor,
extern int scsi_error_handler(void *host);
extern int scsi_decide_disposition(struct scsi_cmnd *cmd);
extern void scsi_eh_wakeup(struct Scsi_Host *shost);
-extern void scsi_eh_scmd_add(struct scsi_cmnd *, int);
+extern void scsi_eh_scmd_add(struct scsi_cmnd *);
void scsi_eh_ready_devs(struct Scsi_Host *shost,
struct list_head *work_q,
struct list_head *done_q);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 36680f1..ed7026c 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -452,11 +452,6 @@ struct scsi_host_template {
unsigned no_write_same:1;

/*
- * True if asynchronous aborts are not supported
- */
- unsigned no_async_abort:1;
-
- /*
* Countdown for host blocking with no commands outstanding.
*/
unsigned int max_host_blocked;
--
1.8.5.6