linux-scsi-owner@xxxxxxxxxxxxxxx wrote on 2015/07/31 21:17:33:
> Hannes Reinecke <hare@xxxxxxx>
> 发件人: linux-scsi-owner@xxxxxxxxxxxxxxx
>
> 2015/07/31 21:17
>
> 收件人
>
> jiang.biao2@xxxxxxxxxx, linux-scsi@xxxxxxxxxxxxxxx, JBottomley@xxxxxxxx,
>
> 抄送
>
> 主题
>
> Re: [Patch] scsi_error: should not get sense for timeout IO in scsi
> error handler
>
> On 07/31/2015 11:52 AM, jiang.biao2@xxxxxxxxxx wrote:
> > scsi_error: should not get sense for timeout IO in scsi error handler
> >
> > When an IO timeout occurs, the IO will be aborted in
> > scsi_abort_command() and SCSI_EH_ABORT_SCHEDULED will be set. Because
> > of that, the SCSI_EH_CANCEL_CMD will be clear in scsi_eh_scmd_add().
> > So when scsi error handler starts, it will get sense for this
> > timeout IO and the scmd of the IO request will be reused. In that
> > case, the scmd may be double released when racing with io_done(),
> > which will result in crash.
> > SO SCSI_EH_ABORT_SCHEDULED should also be checked when getting sense.
> > The bug maybe reproduced when the link between host and disk is
> > unstable.
> >
> > Signed-off-by: Jiang Biao <jiang.biao2@xxxxxxxxxx>
> > Signed-off-by: Long Chun <long.chun@xxxxxxxxxx>
> > Reviewed-by: Tan Hu <tan.hu@xxxxxxxxxx>
> > Reviewed-by: Chen Donghai <chen.donghai@xxxxxxxxxx>
> > Reviewed-by: Cai Qu <cai.qu@xxxxxxxxxx>
> >
> > diff -uprN drivers/scsi/scsi_error.c drivers_new/scsi/scsi_error.c
> > --- scsi/scsi_error.c 2015-07-31 16:03:18.000000000 +0800
> > +++ scsi_new/scsi_error.c 2015-07-31 16:29:25.000000000 +0800
> > @@ -1156,9 +1156,14 @@ int scsi_eh_get_sense(struct list_head *
> > struct Scsi_Host *shost;
> > int rtn;
> >
> > + /*
> > + * If SCSI_EH_ABORT_SCHEDULED has been set, it is timeout IO,
> > + * should not get sense.
> > + */
> > list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
> > if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
> > - SCSI_SENSE_VALID(scmd))
> > + (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) ||
> > + SCSI_SENSE_VALID(scmd))
> > continue;
> >
> > shost = scmd->device->host;
> > --
> _Actually_ you need to test for both, SCSI_EH_CANCEL_CMD _and_
> SCSI_EH_ABORT_SCHEDULED.
> Not every driver is required to implement and/or support
> asynchronous command aborts, and those will be setting
> SCSI_EH_CANCEL_CMD even though they've run into a timeout.
>
That's right, but SCSI_EH_CANCEL_CMD _has_ already been tested
in the current code, so there's no need to add in the patch.
After patched, both SCSI_EH_CANCEL_CMD _and_
SCSI_EH_ABORT_SCHEDULED are tested here, that'll ensure no
getting sense for *timeout io*.
Thanks.
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