[v6,01/11] ASoC: topology: Make manifest backward compatible from ABI v4

Commit Message

[e-mail] Oct. 11, 2016, 6:36 a.m. UTC

From: Mengdong Lin <[e-mail]>

This patch adds support for old version 4 of manifest.

Topology ABI v5 added new fields to manifest while user space may still
uses v4. So kernel will check the ABI version by comparing the object
size. If user space uses v4 of manifest, kernel will create a latest
version of manifest from the old one, and use the new one internally and
free it later.

Signed-off-by: Mengdong Lin <[e-mail]>

Comments

Mark Brown Oct. 28, 2016, 6:47 p.m. UTC | #1

On Tue, Oct 11, 2016 at 02:36:42PM +0800, [e-mail] wrote:

> +static int manifest_new_ver(struct soc_tplg *tplg,
> +			    struct snd_soc_tplg_manifest *src,
> +			    struct snd_soc_tplg_manifest **manifest)
> +{
> +	struct snd_soc_tplg_manifest *dest;
> +	struct snd_soc_tplg_manifest_v4 *src_v4;
> +
> +	*manifest = NULL;
> +
> +	if (src->size != sizeof(*src_v4)) {
> +		dev_err(tplg->dev, "ASoC: invalid manifest size\n");
> +		return -EINVAL;
> +	}
> +
> +	dev_warn(tplg->dev, "ASoC: old version of manifest\n");

The way this function is written it's not going to scale to any future
ABI churn, it's not set up to handle multiple versions at all.

Lin, Mengdong Nov. 1, 2016, 1:49 p.m. UTC | #2

> -----Original Message-----
> From: Mark Brown [mailto:[e-mail]]
> Sent: Saturday, October 29, 2016 2:47 AM
> To: [e-mail]
> Cc: [e-mail]; [e-mail];
> [e-mail]; Shah, Hardik T <[e-mail]>;
> Singh, Guneshwor O <[e-mail]>; Koul, Vinod
> <[e-mail]>; Ughreja, Rakesh A <[e-mail]>;
> Lin, Mengdong <[e-mail]>
> Subject: Re: [PATCH v6 01/11] ASoC: topology: Make manifest backward
> compatible from ABI v4
> 
> On Tue, Oct 11, 2016 at 02:36:42PM +0800, [e-mail]
> wrote:
> 
> > +static int manifest_new_ver(struct soc_tplg *tplg,
> > +			    struct snd_soc_tplg_manifest *src,
> > +			    struct snd_soc_tplg_manifest **manifest) {
> > +	struct snd_soc_tplg_manifest *dest;
> > +	struct snd_soc_tplg_manifest_v4 *src_v4;
> > +
> > +	*manifest = NULL;
> > +
> > +	if (src->size != sizeof(*src_v4)) {
> > +		dev_err(tplg->dev, "ASoC: invalid manifest size\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	dev_warn(tplg->dev, "ASoC: old version of manifest\n");
> 
> The way this function is written it's not going to scale to any future ABI
> churn, it's not set up to handle multiple versions at all.

If future ABI change affects this manifest struct, we'll extend this function to map all old versions to the latest one. 

Since we already add some reserved fields in the manifest, so we can use those reserved fields to assure backward compatibility and there could be no change on this function.

Thanks
Mengdong

Patch

diff --git a/sound/soc/soc-topology.c b/sound/soc/soc-topology.c
index 6b05047..c832b24 100644
--- a/sound/soc/soc-topology.c
+++ b/sound/soc/soc-topology.c
@@ -53,6 +53,23 @@ 
 #define SOC_TPLG_PASS_START	SOC_TPLG_PASS_MANIFEST
 #define SOC_TPLG_PASS_END	SOC_TPLG_PASS_BE_DAI
 
+
+/*
+ * Old version of ABI structs, supported for backward compatibility.
+ */
+
+/* Manifest v4 */
+struct snd_soc_tplg_manifest_v4 {
+	__le32 size;		/* in bytes of this structure */
+	__le32 control_elems;	/* number of control elements */
+	__le32 widget_elems;	/* number of widget elements */
+	__le32 graph_elems;	/* number of graph elements */
+	__le32 pcm_elems;	/* number of PCM elements */
+	__le32 dai_link_elems;	/* number of DAI link elements */
+	struct snd_soc_tplg_private priv;
+} __packed;
+
+/* topology context */
 struct soc_tplg {
 	const struct firmware *fw;
 
@@ -1798,27 +1815,81 @@  static int soc_tplg_be_dai_elems_load(struct soc_tplg *tplg,
 	return 0;
 }
 
+/**
+ * manifest_new_ver - Create a new version of manifest from the old version
+ * of source.
+ * @toplogy: topology context
+ * @src: old version of manifest as a source
+ * @manifest: latest version of manifest created from the source
+ *
+ * Support from vesion 4. Users need free the returned manifest manually.
+ */
+static int manifest_new_ver(struct soc_tplg *tplg,
+			    struct snd_soc_tplg_manifest *src,
+			    struct snd_soc_tplg_manifest **manifest)
+{
+	struct snd_soc_tplg_manifest *dest;
+	struct snd_soc_tplg_manifest_v4 *src_v4;
+
+	*manifest = NULL;
+
+	if (src->size != sizeof(*src_v4)) {
+		dev_err(tplg->dev, "ASoC: invalid manifest size\n");
+		return -EINVAL;
+	}
+
+	dev_warn(tplg->dev, "ASoC: old version of manifest\n");
+
+	src_v4 = (struct snd_soc_tplg_manifest_v4 *)src;
+	dest = kzalloc(sizeof(*dest) + src_v4->priv.size, GFP_KERNEL);
+	if (!dest)
+		return -ENOMEM;
+
+	dest->size = sizeof(*dest);	/* size of latest abi version */
+	dest->control_elems = src_v4->control_elems;
+	dest->widget_elems = src_v4->widget_elems;
+	dest->graph_elems = src_v4->graph_elems;
+	dest->pcm_elems = src_v4->pcm_elems;
+	dest->dai_link_elems = src_v4->dai_link_elems;
+	dest->priv.size = src_v4->priv.size;
+	if (dest->priv.size)
+		memcpy(dest->priv.data, src_v4->priv.data,
+		       src_v4->priv.size);
+
+	*manifest = dest;
+	return 0;
+}
 
 static int soc_tplg_manifest_load(struct soc_tplg *tplg,
 				  struct snd_soc_tplg_hdr *hdr)
 {
-	struct snd_soc_tplg_manifest *manifest;
+	struct snd_soc_tplg_manifest *manifest, *_manifest;
+	bool abi_match;
+	int err;
 
 	if (tplg->pass != SOC_TPLG_PASS_MANIFEST)
 		return 0;
 
 	manifest = (struct snd_soc_tplg_manifest *)tplg->pos;
-	if (manifest->size != sizeof(*manifest)) {
-		dev_err(tplg->dev, "ASoC: invalid manifest size\n");
-		return -EINVAL;
-	}
 
-	tplg->pos += sizeof(struct snd_soc_tplg_manifest);
+	/* check ABI version by size, create a new manifest if abi not match */
+	if (manifest->size == sizeof(*manifest)) {
+		abi_match = true;
+		_manifest = manifest;
+	} else {
+		abi_match = false;
+		err = manifest_new_ver(tplg, manifest, &_manifest);
+		if (err < 0)
+			return err;
+	}
 
+	/* pass control to component driver for optional further init */
 	if (tplg->comp && tplg->ops && tplg->ops->manifest)
-		return tplg->ops->manifest(tplg->comp, manifest);
+		return tplg->ops->manifest(tplg->comp, _manifest);
+
+	if (!abi_match)	/* free the duplicated one */
+		kfree(_manifest);
 
-	dev_err(tplg->dev, "ASoC: Firmware manifest not supported\n");
 	return 0;
 }