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ALSA: firewire-lib: taskletize the snd_pcm_period_elapsed() call

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The following patch might introduce this call chain:
  PCM .pointer callback
  + fw_iso_context_flush_completions
    + packet callback
      + snd_pcm_period_elapsed
        + PCM .pointer callback
Recursive calls to the pointer callback are not possible due to the PCM
group locking, so avoid this by moving the period notification into
a separate tasklet.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2012-05-13 22:03:09 +02:00 committed by Takashi Iwai
parent 7df4a691fb
commit 76fb878948
2 changed files with 31 additions and 13 deletions
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29
sound/firewire/amdtp.c
View File

@ -31,6 +31,8 @@
#define INTERRUPT_INTERVAL 16
#define QUEUE_LENGTH 48
static void pcm_period_tasklet(unsigned long data);
/**
* amdtp_out_stream_init - initialize an AMDTP output stream structure
* @s: the AMDTP output stream to initialize
@ -47,6 +49,7 @@ int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,
s->flags = flags;
s->context = ERR_PTR(-1);
mutex_init(&s->mutex);
tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s);
s->packet_index = 0;
return 0;
@ -164,6 +167,20 @@ void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s,
}
EXPORT_SYMBOL(amdtp_out_stream_set_pcm_format);
/**
* amdtp_out_stream_pcm_prepare - prepare PCM device for running
* @s: the AMDTP output stream
*
* This function should be called from the PCM device's .prepare callback.
*/
void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s)
{
tasklet_kill(&s->period_tasklet);
s->pcm_buffer_pointer = 0;
s->pcm_period_pointer = 0;
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare);
static unsigned int calculate_data_blocks(struct amdtp_out_stream *s)
{
unsigned int phase, data_blocks;
@ -376,11 +393,20 @@ static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
s->pcm_period_pointer += data_blocks;
if (s->pcm_period_pointer >= pcm->runtime->period_size) {
s->pcm_period_pointer -= pcm->runtime->period_size;
snd_pcm_period_elapsed(pcm);
tasklet_hi_schedule(&s->period_tasklet);
}
}
}
static void pcm_period_tasklet(unsigned long data)
{
struct amdtp_out_stream *s = (void *)data;
struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
if (pcm)
snd_pcm_period_elapsed(pcm);
}
static void out_packet_callback(struct fw_iso_context *context, u32 cycle,
size_t header_length, void *header, void *data)
{
@ -532,6 +558,7 @@ void amdtp_out_stream_stop(struct amdtp_out_stream *s)
return;
}
tasklet_kill(&s->period_tasklet);
fw_iso_context_stop(s->context);
fw_iso_context_destroy(s->context);
s->context = ERR_PTR(-1);

15
sound/firewire/amdtp.h
View File

@ -1,6 +1,7 @@
#ifndef SOUND_FIREWIRE_AMDTP_H_INCLUDED
#define SOUND_FIREWIRE_AMDTP_H_INCLUDED
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include "packets-buffer.h"
@ -55,6 +56,7 @@ struct amdtp_out_stream {
struct iso_packets_buffer buffer;
struct snd_pcm_substream *pcm;
struct tasklet_struct period_tasklet;
int packet_index;
unsigned int data_block_counter;
@ -81,6 +83,7 @@ void amdtp_out_stream_stop(struct amdtp_out_stream *s);
void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s,
snd_pcm_format_t format);
void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s);
void amdtp_out_stream_pcm_abort(struct amdtp_out_stream *s);
/**
@ -122,18 +125,6 @@ static inline bool amdtp_out_streaming_error(struct amdtp_out_stream *s)
return s->packet_index < 0;
}
/**
* amdtp_out_stream_pcm_prepare - prepare PCM device for running
* @s: the AMDTP output stream
*
* This function should be called from the PCM device's .prepare callback.
*/
static inline void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s)
{
s->pcm_buffer_pointer = 0;
s->pcm_period_pointer = 0;
}
/**
* amdtp_out_stream_pcm_trigger - start/stop playback from a PCM device
* @s: the AMDTP output stream