On 9/12/05, Thomas Kleffel <[email protected]> wrote:
> Hi,
>
> Bartlomiej Zolnierkiewicz wrote:
>
> >> [...]
> >>1b) When a disk is released by disk_release(), its queue's reference
> >>count shall be decremented by calling blk_cleanup_queue().
> >
> >
> > Which conflicts with IDE layer reference counting & locking scheme
> > as IDE layer can send (special) requests to the device without any
> > device driver loaded.
>
> But the IDE layer won't do that anymore after ide_unregister() was
> called, while a device driver doesn't know that the device doesn't exist
> anymore, so it may still access the queue until it releases the disk.
The point is that you have added blk_cleanup_queue() to the ide-disk
driver release function and it is perfectly fine for IDE layer to send requests
after unloading ide-disk driver.
> >>2a) When a physical drive is released by drive_release_dev(), the
> >>corresponding queue is marked dead, so that no further calls to the
> >>physical device's queue-handler are made.
> >>
> >>2b) When a request is submitted to a dead queue using
> >>generic_make_request(), the request shall be failed immedaiately with
> >>-ENXIO which causes the caller to recive a "Bus error". This is the same
> >>beaviour as when a USB-Storage device gets pulled while in use.
> >
> >
> > The fix would be to fail the previous requests during removal of the
> > device [ somebody already posted a patch to do that but I didn't have
> > time to give it proper thought ] or alternatively to add the offline state to
> > the device [ so processing of the requests would be resumed after device
> > is online again ].
>
> I don't think it'd be wise to resume request processing on the same
> device as the CF Card inserted again might not be the same one as the
> user pulled out before. Performing old, cached writes on the new card
> could destroy innocent data.
Yes, that is why failing old requests is a preferred solution.
> From your responses I read that the correct solution would be to keep
> the old pysical device as long as the ide layer still has references to
> it and to fail all requests in the meantime.
>
> Is that correct?
Yes, we should just fail all the requests if the device is not present.
[ What do you mean by the old physical device, old 'ide_drive_t *'? ]
Regards,
Bartlomiej
> Best regards,
>
> Thomas
>
>
>
>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |