ALSA: firewire-lib: taskletize the snd_pcm_period_elapsed() call
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>
diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
index 87657dd..3284ee9 100644
--- a/sound/firewire/amdtp.c
+++ b/sound/firewire/amdtp.c
@@ -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 @@
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 @@
}
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 @@
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 @@
return;
}
+ tasklet_kill(&s->period_tasklet);
fw_iso_context_stop(s->context);
fw_iso_context_destroy(s->context);
s->context = ERR_PTR(-1);