From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 23 Nov 2007 14:46:48 +0000 (+0100)
Subject: Fix mmap with multi plugin
X-Git-Tag: v1.0.16rc1~44
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=0b66de95a9733dfbe0292bc41324582edc13550c;p=alsa-lib.git

Fix mmap with multi plugin

The mmap of multi plugin seems broken (for a long time!) due to its
creation of local buffer via snd_pcm_mmap().  Since the multi plugin
just needs to shadow the mmap buffer of each slave, it now has
mmap_shadow=1 and its own mmap/unmap method to do shadowing.
---

diff --git a/src/pcm/pcm_multi.c b/src/pcm/pcm_multi.c
index e15038cc..dfd679cc 100644
--- a/src/pcm/pcm_multi.c
+++ b/src/pcm/pcm_multi.c
@@ -690,13 +690,44 @@ static snd_pcm_sframes_t snd_pcm_multi_mmap_commit(snd_pcm_t *pcm,
 	return size;
 }
 
-static int snd_pcm_multi_mmap(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
+static int snd_pcm_multi_munmap(snd_pcm_t *pcm)
 {
+	free(pcm->mmap_channels);
+	free(pcm->running_areas);
+	pcm->mmap_channels = NULL;
+	pcm->running_areas = NULL;
 	return 0;
 }
 
-static int snd_pcm_multi_munmap(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
+static int snd_pcm_multi_mmap(snd_pcm_t *pcm)
 {
+	snd_pcm_multi_t *multi = pcm->private_data;
+	unsigned int c;
+
+	pcm->mmap_channels = calloc(pcm->channels,
+				    sizeof(pcm->mmap_channels[0]));
+	pcm->running_areas = calloc(pcm->channels,
+				    sizeof(pcm->running_areas[0]));
+	if (!pcm->mmap_channels || !pcm->running_areas) {
+		snd_pcm_multi_munmap(pcm);
+		return -ENOMEM;
+	}
+
+	/* Copy the slave mmapped buffer data */
+	for (c = 0; c < pcm->channels; c++) {
+		snd_pcm_multi_channel_t *chan = &multi->channels[c];
+		snd_pcm_t *slave;
+		if (chan->slave_idx < 0) {
+			snd_pcm_multi_munmap(pcm);
+			return -ENXIO;
+		}
+		slave = multi->slaves[chan->slave_idx].pcm;
+		pcm->mmap_channels[c] =
+			slave->mmap_channels[chan->slave_channel];
+		pcm->mmap_channels[c].channel = c;
+		pcm->running_areas[c] =
+			slave->running_areas[chan->slave_channel];
+	}
 	return 0;
 }
 
@@ -850,6 +881,7 @@ int snd_pcm_multi_open(snd_pcm_t **pcmp, const char *name,
 		return err;
 	}
 	pcm->mmap_rw = 1;
+	pcm->mmap_shadow = 1; /* has own mmap method */
 	pcm->ops = &snd_pcm_multi_ops;
 	pcm->fast_ops = &snd_pcm_multi_fast_ops;
 	pcm->private_data = multi;