| From b721e68bdc5b39c51bf6a1469f8d3663fbe03243 Mon Sep 17 00:00:00 2001 |
| From: Giuliano Pochini <pochini@shiny.it> |
| Date: Wed, 17 Feb 2010 00:57:44 +0100 |
| Subject: ALSA: Echoaudio, fix Guru Meditation #00000005.48454C50 |
| |
| From: Giuliano Pochini <pochini@shiny.it> |
| |
| commit b721e68bdc5b39c51bf6a1469f8d3663fbe03243 upstream. |
| |
| This patch fixes a division by zero error in the irq handler. |
| |
| There is a small window between the hw_params() callback and when |
| runtime->frame_bits is set by ALSA middle layer. When another substream is |
| already running, if an interrupt is delivered during that window the irq |
| handler calls pcm_pointer() which does a division by zero. The patch below |
| makes the irq handler skip substreams that are initialized but not started |
| yet. Cc to Clemens Ladisch because he proposed an alternate fix. |
| |
| For more information, please read the original thread in the linux-kernel |
| mailing list: http://lkml.org/lkml/2010/2/2/187 |
| |
| Signed-off-by: Giuliano Pochini <pochini@shiny.it> |
| Signed-off-by: Takashi Iwai <tiwai@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| sound/pci/echoaudio/echoaudio.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/sound/pci/echoaudio/echoaudio.c |
| +++ b/sound/pci/echoaudio/echoaudio.c |
| @@ -1821,7 +1821,9 @@ static irqreturn_t snd_echo_interrupt(in |
| /* The hardware doesn't tell us which substream caused the irq, |
| thus we have to check all running substreams. */ |
| for (ss = 0; ss < DSP_MAXPIPES; ss++) { |
| - if ((substream = chip->substream[ss])) { |
| + substream = chip->substream[ss]; |
| + if (substream && ((struct audiopipe *)substream->runtime-> |
| + private_data)->state == PIPE_STATE_STARTED) { |
| period = pcm_pointer(substream) / |
| substream->runtime->period_size; |
| if (period != chip->last_period[ss]) { |
