Kernel 3.0.8 audio dataflow

Kernel 2.6.32

for (;;) {if (signal_pending(current)) {err = -ERESTARTSYS;break;}set_current_state(TASK_INTERRUPTIBLE);snd_pcm_stream_unlock_irq(substream);tout = schedule_timeout(msecs_to_jiffies(10000));snd_pcm_stream_lock_irq(substream);

 

Kernel 3.0.8

if (runtime->no_period_wakeup)wait_time = MAX_SCHEDULE_TIMEOUT;else {wait_time = 10;if (runtime->rate) {long t = runtime->period_size * 2 / runtime->rate;wait_time = max(t, wait_time);}wait_time = msecs_to_jiffies(wait_time * 1000);}for (;;) {if (signal_pending(current)) {err = -ERESTARTSYS;break;}/* * We need to check if space became available already * (and thus the wakeup happened already) first to close * the race of space already having become available. * This check must happen after been added to the waitqueue * and having current state be INTERRUPTIBLE. */if (is_playback)avail = snd_pcm_playback_avail(runtime);elseavail = snd_pcm_capture_avail(runtime);if (avail >= runtime->twake)break;snd_pcm_stream_unlock_irq(substream);tout = schedule_timeout(wait_time);snd_pcm_stream_lock_irq(substream);

When I saw the kernel code, I thought that Linux would also put this kind of error. The low-level spam Code, although I am working on it now, I still think it is unreasonable.

In the evening, I couldn't help reading the 3.0.8 code. I ran here directly, but I was not disappointed. I had some time to continue reading the code ~~