At Sat, 15 Aug 2009 23:40:36 -0400, Jon Smirl wrote:
On Sat, Aug 15, 2009 at 11:53 AM, Jon Smirljonsmirl@gmail.com wrote:
void bfio_synch_stop(void) { int n;
if (base_handle == NULL) { return; } FOR_IN_AND_OUT { for (n = 0; n < n_handles[IO]; n++) {
I added: snd_pcm_nonblock(handles[IO][n], 0) snd_pcm_drain(handles[IO][n]) snd_pcm_nonblock(handles[IO][n], SND_PCM_NONBLOCK )
snd_pcm_close(handles[IO][n]); } } }
This is not working correctly. snd_pcm_nonblock(handles[IO][n], 0) It does not remove O_NONBLOCK for some unknown reason.
I added printf() to snd_pcm_hw_nonblock() The fcntl is not getting an error. if (fcntl(fd, F_SETFL, flags) < 0) { Flags being set are 2 (O_RDWR).
But when I get over to snd_pcm_pre_drain_init(), I get the -EAGAIN error. static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream, int state) { printk("snd_pcm_pre_drain_init\n"); if (substream->f_flags & O_NONBLOCK) return -EAGAIN; printk("snd_pcm_pre_drain_init 1\n"); substream->runtime->trigger_master = substream; return 0; } So I have to conclude that fcntl(fd, F_SETFL, flags) is not removing the O_NONBLOCK flag.
Yeah, you found a long-standing bug :)
Honestly, I think the current designed behavior is just annoying. An ioctl may be blocked, thus there is no real merit to return -EAGAIN with DRAIN ioctl.
So, my preferred solution is simply to remove the O_NONBLOCK check in the code path above.
Another solution would be a patch like below (totally untested)...
Comments?
thanks,
Takashi
--- diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index d89c816..5d6b9ad 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -1343,8 +1343,6 @@ static int snd_pcm_prepare(struct snd_pcm_substream *substream,
static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream, int state) { - if (substream->f_flags & O_NONBLOCK) - return -EAGAIN; substream->runtime->trigger_master = substream; return 0; } @@ -1404,7 +1402,8 @@ static int snd_pcm_drop(struct snd_pcm_substream *substream); * After this call, all streams are supposed to be either SETUP or DRAINING * (capture only) state. */ -static int snd_pcm_drain(struct snd_pcm_substream *substream) +static int snd_pcm_drain(struct snd_pcm_substream *substream, + struct file *file) { struct snd_card *card; struct snd_pcm_runtime *runtime; @@ -1412,6 +1411,14 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream) int result = 0; int i, num_drecs; struct drain_rec *drec, drec_tmp, *d; + int f_flags; + + if (file) + f_flags = file->f_flags; + else + f_flags = substream->f_flags; + if (f_flags & O_NONBLOCK) + return -EAGAIN;
card = substream->pcm->card; runtime = substream->runtime; @@ -2556,7 +2563,7 @@ static int snd_pcm_common_ioctl1(struct file *file, return snd_pcm_hw_params_old_user(substream, arg); #endif case SNDRV_PCM_IOCTL_DRAIN: - return snd_pcm_drain(substream); + return snd_pcm_drain(substream, file); case SNDRV_PCM_IOCTL_DROP: return snd_pcm_drop(substream); case SNDRV_PCM_IOCTL_PAUSE: