Re: [PATCH]usx2y: prevent oops & dead keyboard on hot usb unplugging

[Takashi Iwai <tiwai@suse.de>]

At Tue, 19 Apr 2005 23:22:06 +0200 (CEST),
karsten wiese wrote:
> 
> 
> --- Takashi Iwai <tiwai@suse.de> wrote:
> > At Sat, 16 Apr 2005 02:31:06 +0200 (CEST),
> > karsten wiese wrote:
> > > 
> > > --- Clemens Ladisch <clemens@ladisch.de> wrote:
> > > > Takashi Iwai wrote:
> > > > > karsten wiese wrote:
> > > > > > (-: You apply my patch now?
> > > > >
> > > > > No, not enough :)  This is exactly why
> > > > snd_card_free_in_thread() was
> > > > > introduced.
> > > > >
> > > > > As I asked, please make sure that the files are all
> > > > released before
> > > > > snd_card_free().  Otherwise the disconnect callback
> > > > hangs at this
> > > > > point because of this check.
> > > > 
> > > > Most programs close the device file when an error
> > occurs,
> > > > so you have
> > > > to test it with something like this to keep the file
> > > > open:
> > > > 
> > > > #include <stdio.h>
> > > > int main()
> > > > {
> > > >   fopen("/dev/snd/hwC1D0", "rb");
> > > >   getchar();
> > > > }
> > > > 
> > > Tested with it, see attached shell log (copied+pasted).
> > > Any more tests needed?
> > 
> > Did you check whether the release fops callback
> > (e.g. snd_hwdep_release) is called?
> 
> Yes: All snd_*_release() functions call 
> snd_card_file_remove() and snd_card_file_remove() definitly
> was called as usX2Y_usb_disconnect() finished correctly,
> when the client closed it's fd(s).
> Only snd_card_file_remove() calls
> wake_up(&card->shutdown_sleep).
> Only other places where snd_card_file_remove() is called
> are the snd_*_open() functions error paths, but those where
> not involved, as lsof stabily showed that /dev/snd/hwC1D0
> was held open by a.out (the client).

OK, thanks for the confirmation!

Now I applied your patch (also modified usbaudio.c) together with
the kernel version check in *.patch files.


Takashi


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