Messages in this thread | | | Subject | Re: [PATCH v2] scsi: Add 'retry_timeout' to avoid infinite command retry | From | James Bottomley <> | Date | Thu, 06 Feb 2014 21:46:43 -0800 |
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On Fri, 2014-02-07 at 09:22 +0900, Eiichi Tsukata wrote: > Currently, scsi error handling in scsi_io_completion() tries to > unconditionally requeue scsi command when device keeps some error state. > For example, UNIT_ATTENTION causes infinite retry with > action == ACTION_RETRY. > This is because retryable errors are thought to be temporary and the scsi > device will soon recover from those errors. Normally, such retry policy is > appropriate because the device will soon recover from temporary error state.
> But there is no guarantee that device is able to recover from error state > immediately. Actually, we've experienced an infinite retry on some hardware. > Therefore hardware error can results in infinite command retry loop.
Could you please add an analysis of the actual failure; which devices and what conditions.
> This patch adds 'retry_timeout' sysfs attribute which limits the retry time > of each scsi command. This attribute is located in scsi sysfs directory > for example "/sys/bus/scsi/devices/X:X:X:X/" and value is in seconds. > Once scsi command retry time is longer than this timeout, > the command is treated as failure. 'retry_timeout' is set to '0' by default > which means no timeout set.
Don't do this ... you're mixing a feature (which you'd need to justify) with an apparent bug fix.
Once you dump all the complexity, I think the patch boils down to a simple check before the action switch in scsi_io_completion():
if (action != ACTION_FAIL && time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { action = ACTION_FAIL; description = "command timed out"; }
James
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