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[SCSI] improved eh timeout handler 

When a command runs into a timeout we need to send an 'ABORT TASK'
TMF. This is typically done by the 'eh_abort_handler' LLDD callback.

Conceptually, however, this function is a normal SCSI command, so
there is no need to enter the error handler.

This patch implements a new scsi_abort_command() function which
invokes an asynchronous function scsi_eh_abort_handler() to
abort the commands via the usual 'eh_abort_handler'.

If abort succeeds the command is either retried or terminated,
depending on the number of allowed retries. However, 'eh_eflags'
records the abort, so if the retry would fail again the
command is pushed onto the error handler without trying to
abort it (again); it'll be cleared up from SCSI EH.

[hare: smatch detected stray switch fixed]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Hannes Reinecke 2013-11-11 13:44:54 +01:00 committed by James Bottomley
parent 2451079bc2
commit e494f6a728
6 changed files with 167 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/scsi/hosts.c
View File

@ -169,6 +169,7 @@ void scsi_remove_host(struct Scsi_Host *shost)
spin_unlock_irqrestore(shost->host_lock, flags);
scsi_autopm_get_host(shost);
flush_workqueue(shost->tmf_work_q);
scsi_forget_host(shost);
mutex_unlock(&shost->scan_mutex);
scsi_proc_host_rm(shost);
@ -294,6 +295,8 @@ static void scsi_host_dev_release(struct device *dev)
scsi_proc_hostdir_rm(shost->hostt);
if (shost->tmf_work_q)
destroy_workqueue(shost->tmf_work_q);
if (shost->ehandler)
kthread_stop(shost->ehandler);
if (shost->work_q)
@ -360,7 +363,6 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
INIT_LIST_HEAD(&shost->eh_cmd_q);
INIT_LIST_HEAD(&shost->starved_list);
init_waitqueue_head(&shost->host_wait);
mutex_init(&shost->scan_mutex);
/*
@ -444,9 +446,19 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
goto fail_kfree;
}
shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
WQ_UNBOUND | WQ_MEM_RECLAIM,
1, shost->host_no);
if (!shost->tmf_work_q) {
printk(KERN_WARNING "scsi%d: failed to create tmf workq\n",
shost->host_no);
goto fail_kthread;
}
scsi_proc_hostdir_add(shost->hostt);
return shost;
fail_kthread:
kthread_stop(shost->ehandler);
fail_kfree:
kfree(shost);
return NULL;

3
drivers/scsi/scsi.c
View File

@ -297,6 +297,7 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
cmd->device = dev;
INIT_LIST_HEAD(&cmd->list);
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
spin_lock_irqsave(&dev->list_lock, flags);
list_add_tail(&cmd->list, &dev->cmd_list);
spin_unlock_irqrestore(&dev->list_lock, flags);
@ -353,6 +354,8 @@ void scsi_put_command(struct scsi_cmnd *cmd)
list_del_init(&cmd->list);
spin_unlock_irqrestore(&cmd->device->list_lock, flags);
cancel_delayed_work(&cmd->abort_work);
__scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_put_command);

151
drivers/scsi/scsi_error.c
View File

@ -53,6 +53,8 @@ static void scsi_eh_done(struct scsi_cmnd *scmd);
#define HOST_RESET_SETTLE_TIME (10)
static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
static int scsi_try_to_abort_cmd(struct scsi_host_template *,
struct scsi_cmnd *);
/* called with shost->host_lock held */
void scsi_eh_wakeup(struct Scsi_Host *shost)
@ -99,6 +101,116 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)
return 1;
}
/**
* scmd_eh_abort_handler - Handle command aborts
* @work: command to be aborted.
*/
void
scmd_eh_abort_handler(struct work_struct *work)
{
struct scsi_cmnd *scmd =
container_of(work, struct scsi_cmnd, abort_work.work);
struct scsi_device *sdev = scmd->device;
unsigned long flags;
int rtn;
spin_lock_irqsave(sdev->host->host_lock, flags);
if (scsi_host_eh_past_deadline(sdev->host)) {
spin_unlock_irqrestore(sdev->host->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"scmd %p eh timeout, not aborting\n",
scmd));
} else {
spin_unlock_irqrestore(sdev->host->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"aborting command %p\n", scmd));
rtn = scsi_try_to_abort_cmd(sdev->host->hostt, scmd);
if (rtn == SUCCESS) {
scmd->result |= DID_TIME_OUT << 16;
if (!scsi_noretry_cmd(scmd) &&
(++scmd->retries <= scmd->allowed)) {
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_WARNING, scmd,
"scmd %p retry "
"aborted command\n", scmd));
scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
} else {
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_WARNING, scmd,
"scmd %p finish "
"aborted command\n", scmd));
scsi_finish_command(scmd);
}
return;
}
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"scmd %p abort failed, rtn %d\n",
scmd, rtn));
}
if (!scsi_eh_scmd_add(scmd, 0)) {
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_WARNING, scmd,
"scmd %p terminate "
"aborted command\n", scmd));
scmd->result |= DID_TIME_OUT << 16;
scsi_finish_command(scmd);
}
}
/**
* scsi_abort_command - schedule a command abort
* @scmd: scmd to abort.
*
* We only need to abort commands after a command timeout
*/
static int
scsi_abort_command(struct scsi_cmnd *scmd)
{
struct scsi_device *sdev = scmd->device;
struct Scsi_Host *shost = sdev->host;
unsigned long flags;
if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {
/*
* Retry after abort failed, escalate to next level.
*/
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"scmd %p previous abort failed\n", scmd));
cancel_delayed_work(&scmd->abort_work);
return FAILED;
}
/*
* Do not try a command abort if
* SCSI EH has already started.
*/
spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_in_recovery(shost)) {
spin_unlock_irqrestore(shost->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"scmd %p not aborting, host in recovery\n",
scmd));
return FAILED;
}
if (shost->eh_deadline && !shost->last_reset)
shost->last_reset = jiffies;
spin_unlock_irqrestore(shost->host_lock, flags);
scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED;
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"scmd %p abort scheduled\n", scmd));
queue_delayed_work(shost->tmf_work_q, &scmd->abort_work, HZ / 100);
return SUCCESS;
}
/**
* scsi_eh_scmd_add - add scsi cmd to error handling.
* @scmd: scmd to run eh on.
@ -125,6 +237,8 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
shost->last_reset = jiffies;
ret = 1;
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++;
@ -161,6 +275,10 @@ enum blk_eh_timer_return scsi_times_out(struct request *req)
else if (host->hostt->eh_timed_out)
rtn = host->hostt->eh_timed_out(scmd);
if (rtn == BLK_EH_NOT_HANDLED && !host->hostt->no_async_abort)
if (scsi_abort_command(scmd) == SUCCESS)
return BLK_EH_NOT_HANDLED;
scmd->result |= DID_TIME_OUT << 16;
if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
@ -1577,7 +1695,7 @@ static void scsi_eh_offline_sdevs(struct list_head *work_q,
}
/**
* scsi_noretry_cmd - determinte if command should be failed fast
* scsi_noretry_cmd - determine if command should be failed fast
* @scmd: SCSI cmd to examine.
*/
int scsi_noretry_cmd(struct scsi_cmnd *scmd)
@ -1585,6 +1703,8 @@ int scsi_noretry_cmd(struct scsi_cmnd *scmd)
switch (host_byte(scmd->result)) {
case DID_OK:
break;
case DID_TIME_OUT:
goto check_type;
case DID_BUS_BUSY:
return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);
case DID_PARITY:
@ -1598,18 +1718,19 @@ int scsi_noretry_cmd(struct scsi_cmnd *scmd)
return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);
}
switch (status_byte(scmd->result)) {
case CHECK_CONDITION:
/*
* assume caller has checked sense and determinted
* the check condition was retryable.
*/
if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
scmd->request->cmd_type == REQ_TYPE_BLOCK_PC)
return 1;
}
if (status_byte(scmd->result) != CHECK_CONDITION)
return 0;
return 0;
check_type:
/*
* assume caller has checked sense and determined
* the check condition was retryable.
*/
if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
scmd->request->cmd_type == REQ_TYPE_BLOCK_PC)
return 1;
else
return 0;
}
/**
@ -1659,9 +1780,13 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
* looks good. drop through, and check the next byte.
*/
break;
case DID_ABORT:
if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {
scmd->result |= DID_TIME_OUT << 16;
return SUCCESS;
}
case DID_NO_CONNECT:
case DID_BAD_TARGET:
case DID_ABORT:
/*
* note - this means that we just report the status back
* to the top level driver, not that we actually think

2
drivers/scsi/scsi_priv.h
View File

@ -19,6 +19,7 @@ struct scsi_nl_hdr;
* 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) \
(((scmd)->sense_buffer[0] & 0x70) == 0x70)
@ -66,6 +67,7 @@ extern int __init scsi_init_devinfo(void);
extern void scsi_exit_devinfo(void);
/* scsi_error.c */
extern void scmd_eh_abort_handler(struct work_struct *work);
extern enum blk_eh_timer_return scsi_times_out(struct request *req);
extern int scsi_error_handler(void *host);
extern int scsi_decide_disposition(struct scsi_cmnd *cmd);

1
include/scsi/scsi_cmnd.h
View File

@ -55,6 +55,7 @@ struct scsi_cmnd {
struct scsi_device *device;
struct list_head list; /* scsi_cmnd participates in queue lists */
struct list_head eh_entry; /* entry for the host eh_cmd_q */
struct delayed_work abort_work;
int eh_eflags; /* Used by error handlr */
/*

10
include/scsi/scsi_host.h
View File

@ -478,6 +478,11 @@ struct scsi_host_template {
/* True if the controller does not support WRITE SAME */
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.
*/
@ -689,6 +694,11 @@ struct Scsi_Host {
char work_q_name[20];
struct workqueue_struct *work_q;
/*
* Task management function work queue
*/
struct workqueue_struct *tmf_work_q;
/*
* Host has rejected a command because it was busy.
*/