linux.git/sound/core/pcm_lib.c, branch v5.0.4

ALSA: pcm: Revert capture stream behavior change in blocking mode

2019-02-08T15:54:31+00:00

In the commit 62ba568f7aef ("ALSA: pcm: Return 0 when size <
start_threshold in capture"), we changed the behavior of
__snd_pcm_lib_xfer() to return immediately with 0 when a capture
stream has a high start_threshold.  This was intended to be a
correction of the behavior consistency and looked harmless, but this
was the culprit of the recent breakage reported by syzkaller, which
was fixed by the commit e190161f96b8 ("ALSA: pcm: Fix tight loop of
OSS capture stream").

At the time for the OSS fix, I didn't touch the behavior for ALSA
native API, as assuming that this behavior actually is good.  But this
turned out to be also broken actually for a similar deployment,
e.g. one thread goes to a write loop in blocking mode while another
thread controls the start/stop of the stream manually.

Overall, the original commit is harmful, and it brings less merit to
keep that behavior.  Let's revert it.

Fixes: 62ba568f7aef ("ALSA: pcm: Return 0 when size < start_threshold in capture")
Fixes: e190161f96b8 ("ALSA: pcm: Fix tight loop of OSS capture stream")
Cc: 
Signed-off-by: Takashi Iwai

ALSA: pcm: Fix tight loop of OSS capture stream

2019-01-25T18:45:46+00:00

When the trigger=off is passed for a PCM OSS stream, it sets the
start_threshold of the given substream to the boundary size, so that
it won't be automatically started.  This can be problematic for a
capture stream, unfortunately, as detected by syzkaller.  The scenario
is like the following:

- In __snd_pcm_lib_xfer() that is invoked from snd_pcm_oss_read()
  loop, we have a check whether the stream was already started or the
  stream can be auto-started.
- The function at this check returns 0 with trigger=off since we
  explicitly disable the auto-start.
- The loop continues and repeats calling __snd_pcm_lib_xfer() tightly,
  which may lead to an RCU stall.

This patch fixes the bug by simply allowing the wait for non-started
stream in the case of OSS capture.  For native usages, it's supposed
to be done by the caller side (which is user-space), hence it returns
zero like before.

(In theory, __snd_pcm_lib_xfer() could wait even for the native API
 usage cases, too; but I'd like to stay in a safer side for not
 breaking the existing stuff for now.)

Reported-by: syzbot+fbe0496f92a0ce7b786c@syzkaller.appspotmail.com
Cc: 
Signed-off-by: Takashi Iwai

ALSA: pcm: Update hardware pointer before start capture

2018-09-10T07:06:55+00:00

This ensures the transfer loop won't waste a run to read
the few frames (if any) between start and hw_ptr update.
It will wait for the next interrupt with wait_for_avail().

Signed-off-by: Ricardo Biehl Pasquali 
Signed-off-by: Takashi Iwai

ALSA: pcm: Return 0 when size < start_threshold in capture

2018-08-27T05:27:55+00:00

In __snd_pcm_lib_xfer(), when capture, if state is PREPARED
and size is less than start_threshold nothing can be done.
As there is no error, 0 is returned.

Signed-off-by: Ricardo Biehl Pasquali 
Signed-off-by: Takashi Iwai

ALSA: pcm: Fix snd_interval_refine first/last with open min/max

2018-07-11T06:49:59+00:00

Without this commit the following intervals [x y), (x y) were be
replaced to (y-1 y) by snd_interval_refine_last(). This was also done
if y-1 is part of the previous interval.
With this changes it will be replaced with [y-1 y) in case of y-1 is
part of the previous interval. A similar behavior will be used for
snd_interval_refine_first().

This commit adapts the changes for alsa-lib of commit
9bb985c ("pcm: snd_interval_refine_first/last: exclude value only if
also excluded before")

Signed-off-by: Timo Wischer 
Signed-off-by: Takashi Iwai

ALSA: pcm: Allow drivers to set R/W wait time.

2018-07-06T13:00:25+00:00

Currently ALSA core blocks userspace for about 10 seconds for PCM R/W IO.
This needs to be configurable for modern hardware like DSPs where no
pointer update in milliseconds can indicate terminal DSP errors.

Add a substream variable to set the wait time in ms. This allows userspace
and drivers to recover more quickly from terminal DSP errors.

Signed-off-by: Liam Girdwood 
Signed-off-by: Takashi Iwai

ALSA: pcm: trace XRUN event at injection, too

2018-07-04T13:34:57+00:00

The PCM xrun injection triggers directly snd_pcm_stop() without the
standard xrun handler, hence it's not recorded on the event buffer.
Ditto for snd_pcm_stop_xrun() call and SNDRV_PCM_IOCTL_XRUN ioctl.
They are inconvenient from the debugging POV.

Let's make them to trigger XRUN via the standard helper more
consistently.

Signed-off-by: Takashi Iwai

ALSA: pcm: Clean up with snd_pcm_avail() and snd_pcm_hw_avail() helpers

2018-04-17T05:37:13+00:00

Introduce two new direction-neutral helpers to calculate the avail and
hw_avail values, and clean up the code with them.

The two separated forward and rewind functions are gathered to the
unified functions.

No functional change but only code reductions.

Reviewed-by: Takashi Sakamoto 
Signed-off-by: Takashi Iwai

ALSA: pcm: Use krealloc() for resizing the rules array

2018-03-13T14:37:58+00:00

Just a minor simplification.  Change from kcalloc() shouldn't matter
as each array element is fully initialized.

Reviewed-by: Takashi Sakamoto 
Signed-off-by: Takashi Iwai

Merge branch 'for-linus' into for-next

2018-01-15T15:45:15+00:00

Back-merge to the development branch for further fixes of sequencer
stuff.

Signed-off-by: Takashi Iwai