commit d4f1e48bd11e3df6a26811f7a1f06c4225d92f7d upstream.

When the loopback timer handler is running, calling del_timer() (for STOP
trigger) will not wait for the handler to complete before deactivating the
timer. The timer gets rescheduled in the handler as usual. Then a subsequent
START trigger will try to start the timer using add_timer() with a timer pending
leading to a kernel panic.

Serialize the calls to add_timer() and del_timer() using a spin lock to avoid
this.

Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit bc733d495267a23ef8660220d696c6e549ce30b3 upstream.

The irq field of struct snd_mpu401 is supposed to be initialized to -1.
Since it's set to zero as of now, a probing error before the irq
installation results in a kernel warning "Trying to free already-free
IRQ 0".

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=44821
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

loopback_pos_update() can be called in the timer callback, thus the lock
held should be irq-safe.  Otherwise you'll get AB/BA deadlock together
with substream->self_group.lock.

Reported-and-tested-by: Knut Petersen <Knut_Petersen@t-online.de>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

For helping to reduce Greert's regression list...
  src/sound/drivers/mtpav.c: error: implicit declaration of function 'inb'
  src/sound/drivers/mtpav.c: error: implicit declaration of function 'outb'
  ...

Signed-off-by: Takashi Iwai <tiwai@suse.de>

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

On SMP machines, the cable->running update must be atomic, otherwise
stream is not started correctly sometimes.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

Show some useful runtime information using procfs.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>