Re: [PATCH] fix pktcdvd breakage from commite105b8bfc769b0545b6f0f395179d1e43cbee822

[Peter Osterlund]

On Sat, 6 Dec 2008, Kay Sievers wrote:

> On Fri, 2008-12-05 at 03:57 +0100, Kay Sievers wrote:
> > On Sun, Nov 30, 2008 at 16:56, Kay Sievers <kay.sievers@xxxxxxxx> wrote:
> > > On Sun, Nov 30, 2008 at 15:52, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> > > > On Sun, Nov 30, 2008 at 03:28:15PM +0100, Kay Sievers wrote:
> > > > > > So we need to preserve the layout, with the easiest way probably being "add
> > > > > > one more ktype and use kobject_init_and_add() instead of that device_create()".
> > > > > > Sigh...
> > > > >
> > > > > What do you mean? We just need to replace the bogus "pd->pkt_dev" with
> > > > > MKDEV(0, 0) and we are fine.
> > > >
> > > > Userland-visible change - right now cat /sys/class/pktcdvd/pktcdvd3/dev will
> > > > give you dev_t of the block device in question.
> > >
> > > True, it's visible, but it's incorrect dead information which should
> > > be removed. Subsystem != "block is defined as S_IFCHR, and there is no
> > > such char device for pktcdvd. In fact the "dev" file of the pktcdvd
> > > class device points in many cases to a USB device, which must be
> > > fixed.
> > >
> > > The whole pktcdvd class is not used at all, besides for exporting a
> > > few files. The "dev" file at the class device is just a bug, and the
> > > MAJOR/MINOR uevent environment variables also. I doubt that there will
> > > be any visible breakage in something that isn't already totally
> > > broken. In short, I doubt, that anything that works today will stop
> > > working if we remove the bugus "dev" file.
> > >
> > > This seem like the simple and correct fix for the issue with /sys/dev/
> > > and the broken non-existing but exported pkcdvd char device:
> > > -               pd->dev = device_create(class_pktcdvd, NULL, pd->pkt_dev, NULL,
> > > +               pd->dev = device_create(class_pktcdvd, NULL, MKDEV(0, 0), NULL,
> >
> > Al, this bug still exists, right? Any objections to remove the dead char dev_t?
>
> Here is a patch.

I can confirm that this patch doesn't seem to cause any negative side 
effects on either pktsetup or pktcdvd, which are the only two user space 
programs I know of that care about the pktcdvd driver.

Acked-by: Peter Osterlund <petero2@xxxxxxxxx>


> Thanks,
> Kay
>
>
> From: Kay Sievers <kay.sievers@xxxxxxxx>
> Subject: pktcdvd: remove broken dev_t export of class devices
>
> The pktcdvd created class devices only export some sysfs files,
> but have no char dev_t registered in the driver.
>
> At class device creation time they copy the dev_t value of the
> block device to the char device, wich will register a new char
> device in the driver core and userspace, with a conflicting dev_t
> value.
>
> In many cases the class devices dev_t just points to a random
> USB device. This fixes the sysfs "duplicate entry" errors.
>
> Cc: petero2@xxxxxxxxx
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Kay Sievers <kay.sievers@xxxxxxxx>
> ---
> pktcdvd.c |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -302,7 +302,7 @@ static struct kobj_type kobj_pkt_type_wqueue = {
> static void pkt_sysfs_dev_new(struct pktcdvd_device *pd)
> {
> 	if (class_pktcdvd) {
> -		pd->dev = device_create(class_pktcdvd, NULL, pd->pkt_dev, NULL,
> +		pd->dev = device_create(class_pktcdvd, NULL, MKDEV(0, 0), NULL,
> 					"%s", pd->name);
> 		if (IS_ERR(pd->dev))
> 			pd->dev = NULL;

--
Peter Osterlund - petero2@xxxxxxxxx
http://web.telia.com/~u89404340
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