Re: [PATCH 0/4] ALSA: fireworks/bebob/dice/oxfw: fix kernel oops at unplugging during streaming

[Takashi Iwai <tiwai@suse.de>]

At Sat, 21 Feb 2015 23:54:56 +0900,
Takashi Sakamoto wrote:
> 
> Each FireWire sound driver causes kernel oops at unplugging during
> streaming. This bug affects:
>  - snd-bebob (in 3.16 or later)
>  - snd-fireworks (in 3.16 or later)
>  - snd-dice (in 3.19 or later)
>  - snd-oxfw (in 3.19 or later)
> 
> When streaming, any ALSA character devices are opened and sound card
> object is referred. Then 'struct snd_card.private_free()' is not executed
> in a context of 'struct fw_driver.remove()'. It's executed in a context of
> an application process in which the last ALSA character device is closed.
> In this case, any operation to instances of FireWire unit is invalid
> because it's already released, and causes kernel oops. I confirm GPF or
> Null-pointer-dereference.
> 
> To fix this problem, this patchset do:
> 1.delegate reference counting of an instance of FireWire unit from AMDTP
>   helper functions to each driver, then do it in
>   'struct snd_card.private_free()'.
> 2.move stream or transaction destructor from 'struct fw_driver.remove()'
>   to 'struct snd_card.private_free()'.
> 
> With this patchset, each driver keeps a reference to FireWire unit till
> all of ALSA applications close its character devices. This may be against
> IEEE 1394 bus driver developers' expectation to high-level drivers.

Thanks, now applied all four patches.


Takashi

> 
> Takashi Sakamoto (4):
>   ALSA: fireworks/bebob/dice/oxfw: add reference-counting for FireWire
>     unit
>   ALSA: firewire-lib: remove reference counting
>   ALSA: fireworks/bebob/dice/oxfw: allow stream destructor after
>     releasing runtime
>   ALSA: fireworks/bebob/dice/oxfw: make it possible to shutdown safely
> 
>  sound/firewire/amdtp.c                      |  3 +--
>  sound/firewire/bebob/bebob.c                | 20 ++++++++++++++++----
>  sound/firewire/bebob/bebob_stream.c         | 16 ++++------------
>  sound/firewire/dice/dice-stream.c           | 18 ++++++++++++------
>  sound/firewire/dice/dice.c                  | 16 +++++++++++-----
>  sound/firewire/fireworks/fireworks.c        | 20 ++++++++++++++------
>  sound/firewire/fireworks/fireworks_stream.c | 19 ++++++++++---------
>  sound/firewire/oxfw/oxfw-stream.c           |  6 ++++--
>  sound/firewire/oxfw/oxfw.c                  | 21 ++++++++++++++-------
>  9 files changed, 86 insertions(+), 53 deletions(-)
> 
> -- 
> 2.1.0
>