ALSA: intel8x0: Don't update period unless prepared
The interrupt handler of intel8x0 calls snd_intel8x0_update() whenever
the hardware sets the corresponding status bit for each stream. This
works fine for most cases as long as the hardware behaves properly.
But when the hardware gives a wrong bit set, this leads to a zero-
division Oops, and reportedly, this seems what happened on a VM.
For fixing the crash, this patch adds a internal flag indicating that
the stream is ready to be updated, and check it (as well as the flag
being in suspended) to ignore such spurious update.
Cc: <stable@vger.kernel.org>
Reported-and-tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Link: https://lore.kernel.org/r/s5h5yzi7uh0.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 35903d1..5b124c4a 100644
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -331,6 +331,7 @@
unsigned int ali_slot; /* ALI DMA slot */
struct ac97_pcm *pcm;
int pcm_open_flag;
+ unsigned int prepared:1;
unsigned int suspended: 1;
};
@@ -691,6 +692,9 @@
int status, civ, i, step;
int ack = 0;
+ if (!ichdev->prepared || ichdev->suspended)
+ return;
+
spin_lock_irqsave(&chip->reg_lock, flags);
status = igetbyte(chip, port + ichdev->roff_sr);
civ = igetbyte(chip, port + ICH_REG_OFF_CIV);
@@ -881,6 +885,7 @@
if (ichdev->pcm_open_flag) {
snd_ac97_pcm_close(ichdev->pcm);
ichdev->pcm_open_flag = 0;
+ ichdev->prepared = 0;
}
err = snd_ac97_pcm_open(ichdev->pcm, params_rate(hw_params),
params_channels(hw_params),
@@ -902,6 +907,7 @@
if (ichdev->pcm_open_flag) {
snd_ac97_pcm_close(ichdev->pcm);
ichdev->pcm_open_flag = 0;
+ ichdev->prepared = 0;
}
return 0;
}
@@ -976,6 +982,7 @@
ichdev->pos_shift = (runtime->sample_bits > 16) ? 2 : 1;
}
snd_intel8x0_setup_periods(chip, ichdev);
+ ichdev->prepared = 1;
return 0;
}
