On Fri, Aug 05, 2005 at 09:45:40PM -0500, James Bottomley wrote:
> There are certain rogue devices (and the aic7xxx driver) that return
> BUSY or QUEUE_FULL forever. This code will apply a global timeout (of
> the total number of retries times the per command timer) to a given
> command. If it is exceeded, the command is completed regardless of its
> state.
Good idea ... sorry I'm late with comments ...
Move the check into scsi_decide_disposition.
It is not clear if DID_IMM_RETRY should ever get a SUCCESS.
What about completely removing cmd->allowed, and only using total time (a
new cmd->io_lifetime, wait_for in your patch) that the IO has been
outstanding as a retry limiter?
Or have allowed and io_lifetime co-exist, I'm not sure which values should
used as the lower or upper limit.
scmd->allowed (and io_lifetime) should be modifiable from user space and
set in uppper levels, like sdev->timeout, instead of hardcoding to the
timeout * allowed.
-- Patrick Mansfield
> James
>
> diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
> --- a/drivers/scsi/advansys.c
> +++ b/drivers/scsi/advansys.c
> @@ -9200,8 +9200,8 @@ asc_prt_scsi_cmnd(struct scsi_cmnd *s)
> (unsigned) s->serial_number, s->retries, s->allowed);
>
> printk(
> -" timeout_per_command %d, timeout_total %d, timeout %d\n",
> - s->timeout_per_command, s->timeout_total, s->timeout);
> +" timeout_per_command %d\n",
> + s->timeout_per_command);
>
> printk(
> " scsi_done 0x%lx, done 0x%lx, host_scribble 0x%lx, result 0x%x\n",
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -268,6 +268,7 @@ struct scsi_cmnd *scsi_get_command(struc
> } else
> put_device(&dev->sdev_gendev);
>
> + cmd->jiffies_at_alloc = jiffies;
> return cmd;
> }
> EXPORT_SYMBOL(scsi_get_command);
> @@ -798,9 +799,23 @@ static void scsi_softirq(struct softirq_
> while (!list_empty(&local_q)) {
> struct scsi_cmnd *cmd = list_entry(local_q.next,
> struct scsi_cmnd, eh_entry);
> + /* The longest time any command should be outstanding is the
> + * per command timeout multiplied by the number of retries.
> + *
> + * For a typical command, this is 2.5 minutes */
> + unsigned long wait_for
> + = cmd->allowed * cmd->timeout_per_command;
> list_del_init(&cmd->eh_entry);
>
> disposition = scsi_decide_disposition(cmd);
> + if (disposition != SUCCESS &&
> + time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
> + dev_printk(KERN_ERR, &cmd->device->sdev_gendev,
> + "timing out command, waited %ds\n",
> + wait_for/HZ);
> + disposition = SUCCESS;
> + }
> +
> scsi_log_completion(cmd, disposition);
> switch (disposition) {
> case SUCCESS:
> diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
> --- a/include/scsi/scsi_cmnd.h
> +++ b/include/scsi/scsi_cmnd.h
> @@ -51,12 +51,16 @@ struct scsi_cmnd {
> * printk's to use ->pid, so that we can kill this field.
> */
> unsigned long serial_number;
> + /*
> + * This is set to jiffies as it was when the command was first
> + * allocated. It is used to time how long the command has
> + * been outstanding
> + */
> + unsigned long jiffies_at_alloc;
>
> int retries;
> int allowed;
> int timeout_per_command;
> - int timeout_total;
> - int timeout;
>
> unsigned char cmd_len;
> unsigned char old_cmd_len;
-
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