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Commit 96295812 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

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



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: default avatarTakashi Iwai <tiwai@suse.de>
parent 6dbaf8b9

include/sound/pcm-indirect.h

+8 −2
Original line number Diff line number Diff line
@@ -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;

}



/*