Hello Hannes,
On Wed, Mar 01, 2017 at 10:15:20AM +0100, Hannes Reinecke wrote:
> 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 <h...@suse.de>
> Reviewed-by: Johannes Thumshirn <jthumsh...@suse.de>
> Reviewed-by: Bart Van Assche <bart.vanass...@sandisk.com>
> ---
> 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 802a081..7b70ee9 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -163,7 +163,7 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host
> *shost)
> }
> }
>
> - scsi_eh_scmd_add(scmd, 0);
> + scsi_eh_scmd_add(scmd);
> }
>
> /**
> @@ -217,9 +217,8 @@ 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;
> @@ -235,9 +234,6 @@ 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;
> scsi_eh_reset(scmd);
> list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
> shost->host_failed++;
> @@ -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;
> @@ -1153,8 +1148,7 @@ 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;
>
> @@ -1294,61 +1288,6 @@ 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
> @@ -1691,11 +1630,6 @@ 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;
> @@ -2139,8 +2073,7 @@ 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 0735a46..98b2df8 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1593,7 +1593,7 @@ 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 5be6cbf6..e20ab10 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 3cd8c3b..afb0481 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
>
Hmm so, I guess we compromise in terms of how granular we want to
recover?
When say an abort for command A on LUN 1 behind Port α fails for some
reason, then we also skip all possible aborts for command B on LUN 2
behind Port α and command C on LUN 1 behind Port β? (The host might
already be in recovery by the time command B and C fail)
I mean, in the end, all traffic holds on that host anyway, as long as we
get into EH - which is true as soon as one abort fails. Might as well
skip the wait time till we get there.
I would like it, if we could document that fact a bit more direct.
Otherwise I think that's good. The code also looks good.
Reviewed-by: Benjamin Block <bbl...@linux.vnet.ibm.com>
Beste Grüße / Best regards,
- Benjamin Block
--
Linux on z Systems Development / IBM Systems & Technology Group
IBM Deutschland Research & Development GmbH
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