Re: [PATCH] scsi: ata: Fix a race condition between scsi error handler and ahci interrupt

[Li Nan]

在 2023/8/14 15:50, Damien Le Moal 写道:
> On 8/14/23 15:41, Li Nan wrote:
> > > This is definitely not correct because EH may have been scheduled for a non
> > > fatal action like a device revalidate or to get sense data for successful
> > > commands. With this change, the port will NOT be frozen when a hard error IRQ
> > > comes while EH is waiting to start, that is, while EH waits for all commands to
> > > complete first.
> >
> > Yeah, we should find a better way to fix it. Do you have any suggesstions?
> >
> > > Furthermore, if you get an IRQ that requires the port to be frozen, it means
> > > that you had a failed command. In that case, the drive is in error state per
> > > ATA specs and stops all communication until a read log 10h command is issued.
> > > So you should never ever see 2 error IRQs one after the other. If you do, it
> > > very likely means that you have buggy hardware.
> > >
> > > How do you get into this situation ? What adapter and disk are you using ?
> >
> >   > How do you get into this situation ?
> > The first IRQ is io error, the second IRQ is disk link flash break.
>
> What does "link flash break" mean ?
>
> >   > What adapter and disk are you using ?
> > It is a disk developed by our company, but we think the same issue
> > exists when using other disks.
>
> As I said, I find this situation highly suspect because if the first IRQ was to
> signal an IO error that the drive reported, then per ATA specifications, the
> drive should be in error mode and should NOT have transmitted any other FIS
> after the SDB FIS that signaled the error. Nothing at all should come after that
> error SDB FIS, until the host issues a read log 10h to get thee drive out of
> error state.
>
> If this is a prototype device, I would recommend that you take an ATA bus trace
> and verify the FIS traffic. Something fishy is going on with the drive in my
> opinion.

Thank you for your patient explanation. I'm sorry I didn't explain the
problem clearly before. After discussing with my colleagues who know
more about dirvers, Let me re-describe the problem.

The problem`s situation is the SATA link is quickly disconnected and 
connected. For example, when an I/O error is processed in error handling 
thread, the disk is manually removed and inserted, and the AHCI chip 
reports a hot plug interrupt.

This scenario is not just an NCQ error, but a disk is removed and 
quickly inserted before the error processing is completed. For the error 
handling process, the disk status needs to be restored after the error 
handling is complete.

--
Thanks,
Nan