Re: S3 with pata_via fails to resume, ide_via82Cxxx works

["Bruno Prémont" <bonbons@linux-vserver.org>]

On Fri, 02 January 2009 Bartlomiej Zolnierkiewicz wrote:
-snip-
> > 
> > I guess the binfmt-0000 is cause by XFS reading at wrong location
> > on disc and kernel seeing random data as bin format signature.
> > 
> > 
> > On reboot no more bootloader.
> > hexdump with rescue system showed XFS magic in very first sector of
> > the disc, (rescuing the GPT worked - I assume parted used copy at
> > end of disc) though the first partition also got corrupted.
> > 
> > This looks like the scan is pretty dangerous in case anything has a
> > reference to a disc/partition on the scanned channel :(

That's fine with me - eventually it would even be worth adding a
printk() as reminder on code path for "scan" and "delete_devices"
triggered when there exists an active user of the bus/device being
probed.

This way there is at least a notice in case something goes wrong (and
when the locking is fixed a reminder to adjust the documentation)

> I'm really sorry to hear it but "delete_devices" / "scan" interfaces
> are currently not ready for use on actively used devices (there are
> still some locking issues with the core code that need to be
> addressed before this can be allowed).
> 
> Even though HOWTO only mentions use for replacing devices (not
> rescaning) I admit that it should be more clear about the above:
> 
> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> Subject: [PATCH] ide: update warm-plug HOWTO
> 
> Reported-by: Bruno Prémont <bonbons@linux-vserver.org>
> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> ---
>  Documentation/ide/warm-plug-howto.txt |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> Index: b/Documentation/ide/warm-plug-howto.txt
> ===================================================================
> --- a/Documentation/ide/warm-plug-howto.txt
> +++ b/Documentation/ide/warm-plug-howto.txt
> @@ -11,3 +11,8 @@ unplug old device(s) and plug new device
>  # echo -n "1" > /sys/class/ide_port/idex/scan
>  
>  done
> +
> +NOTE: please make sure that partitions are unmounted and that there
> are +no other active references to devices before doing
> "delete_devices" step, +also do not attempt "scan" step on devices
> currently in use -- otherwise +results may be unpredictable and lead
> to data loss if you're unlucky
>