There is another possible fix. I tested it briefly. It looks ok wrt race conditions because pipe->state is set only in the trigger callback. I hope I didn't overlook anything again...
Signed-off-by: Giuliano Pochini pochini@shiny.it
--- alsa-driver-1.0.22.1/alsa-kernel/pci/echoaudio/echoaudio.c__orig 2010-02-02 22:37:33.000000000 +0100 +++ alsa-driver-1.0.22.1/alsa-kernel/pci/echoaudio/echoaudio.c 2010-02-02 22:44:03.000000000 +0100 @@ -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]) {