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ALSA: pcm: Fix negative appl_ptr handling in pcm-indirect helpers

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The indirect-PCM helper codes have an implicit assumption that the
appl_ptr always increases.  But the PCM core may deal with the
decrement of appl_ptr via rewind ioctls, and it may screw up the
buffer pointer management.

This patch adds the negative appl_ptr diff in transfer functions and
let returning an error instead of always accepting the appl_ptr
updates.  The callers are usually PCM ack callbacks, and they pass the
error to the upper layer accordingly.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2017-05-19 18:31:03 +02:00
parent 6dbaf8b913
commit 9629581258
1 changed files with 8 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
include/sound/pcm-indirect.h
View file

@ -43,7 +43,7 @@ typedef void (*snd_pcm_indirect_copy_t)(struct snd_pcm_substream *substream,
/*
* helper function for playback ack callback
*/
static inline void
static inline int
snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec,
snd_pcm_indirect_copy_t copy)
@ -56,6 +56,8 @@ snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream,
if (diff) {
if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
diff += runtime->boundary;
if (diff < 0)
return -EINVAL;
rec->sw_ready += (int)frames_to_bytes(runtime, diff);
rec->appl_ptr = appl_ptr;
}
@ -82,6 +84,7 @@ snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream,
rec->hw_ready += bytes;
rec->sw_ready -= bytes;
}
return 0;
}
/*
@ -109,7 +112,7 @@ snd_pcm_indirect_playback_pointer(struct snd_pcm_substream *substream,
/*
* helper function for capture ack callback
*/
static inline void
static inline int
snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec,
snd_pcm_indirect_copy_t copy)
@ -121,6 +124,8 @@ snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
if (diff) {
if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
diff += runtime->boundary;
if (diff < 0)
return -EINVAL;
rec->sw_ready -= frames_to_bytes(runtime, diff);
rec->appl_ptr = appl_ptr;
}
@ -147,6 +152,7 @@ snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
rec->hw_ready -= bytes;
rec->sw_ready += bytes;
}
return 0;
}
/*