Re: [PATCHv2 1/4] fwu: gpt: use cached meta-data partition numbers

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Fri, Dec 02, 2022 at 09:16:51PM -0600, jassisinghbrar@gmail.com wrote:
> From: Jassi Brar <jaswinder.singh@linaro.org>
>
> Use cached values and avoid parsing and scanning through partitions
> everytime for meta-data partitions because they can't change after bootup.
>
> Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
> ---
>  drivers/fwu-mdata/gpt_blk.c | 43 +++++++++++++++++++++----------------
>  1 file changed, 24 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/fwu-mdata/gpt_blk.c b/drivers/fwu-mdata/gpt_blk.c
> index d35ce49c5c..28f5d23e1e 100644
> --- a/drivers/fwu-mdata/gpt_blk.c
> +++ b/drivers/fwu-mdata/gpt_blk.c
> @@ -24,8 +24,9 @@ enum {
>  	MDATA_WRITE,
>  };
>
> -static int gpt_get_mdata_partitions(struct blk_desc *desc,
> -				    uint mdata_parts[2])
> +static uint g_mdata_part[2]; /* = {0, 0} to check against uninit parts */
> +
> +static int gpt_get_mdata_partitions(struct blk_desc *desc)
>  {
>  	int i, ret;
>  	u32 nparts;
> @@ -33,18 +34,19 @@ static int gpt_get_mdata_partitions(struct blk_desc *desc,
>  	struct disk_partition info;
>  	const efi_guid_t fwu_mdata_guid = FWU_MDATA_GUID;
>
> +	/* if primary and secondary partitions already found */
> +	if (g_mdata_part[0] && g_mdata_part[1])
> +		return 0;
> +
>  	nparts = 0;
> -	for (i = 1; i < MAX_SEARCH_PARTITIONS; i++) {
> +	for (i = 1; i < MAX_SEARCH_PARTITIONS && nparts < 2; i++) {
>  		if (part_get_info(desc, i, &info))
>  			continue;
>  		uuid_str_to_bin(info.type_guid, part_type_guid.b,
>  				UUID_STR_FORMAT_GUID);
>
> -		if (!guidcmp(&fwu_mdata_guid, &part_type_guid)) {
> -			if (nparts < 2)
> -				mdata_parts[nparts] = i;
> -			++nparts;
> -		}
> +		if (!guidcmp(&fwu_mdata_guid, &part_type_guid))
> +			g_mdata_part[nparts++] = i;

The reason the 'if (nparts < 2)' was outside the main loop was to show
errors in case the user defined more than two partitions.  Can we keep it
like that or am I the only being paranoid here?

>  	}
>
>  	if (nparts != 2) {
> @@ -127,26 +129,25 @@ static int fwu_gpt_update_mdata(struct udevice *dev, struct fwu_mdata *mdata)
>  {
>  	int ret;
>  	struct blk_desc *desc;
> -	uint mdata_parts[2];
>  	struct fwu_mdata_gpt_blk_priv *priv = dev_get_priv(dev);
>
>  	desc = dev_get_uclass_plat(priv->blk_dev);
>
> -	ret = gpt_get_mdata_partitions(desc, mdata_parts);
> +	ret = gpt_get_mdata_partitions(desc);
>  	if (ret < 0) {
>  		log_debug("Error getting the FWU metadata partitions\n");
>  		return -ENOENT;
>  	}
>
>  	/* First write the primary partition */
> -	ret = gpt_read_write_mdata(desc, mdata, MDATA_WRITE, mdata_parts[0]);
> +	ret = gpt_read_write_mdata(desc, mdata, MDATA_WRITE, g_mdata_part[0]);
>  	if (ret < 0) {
>  		log_debug("Updating primary FWU metadata partition failed\n");
>  		return ret;
>  	}
>
>  	/* And now the replica */
> -	ret = gpt_read_write_mdata(desc, mdata, MDATA_WRITE, mdata_parts[1]);
> +	ret = gpt_read_write_mdata(desc, mdata, MDATA_WRITE, g_mdata_part[1]);
>  	if (ret < 0) {
>  		log_debug("Updating secondary FWU metadata partition failed\n");
>  		return ret;
> @@ -158,16 +159,14 @@ static int fwu_gpt_update_mdata(struct udevice *dev, struct fwu_mdata *mdata)
>  static int gpt_get_mdata(struct blk_desc *desc, struct fwu_mdata *mdata)
>  {
>  	int ret;
> -	uint mdata_parts[2];
> -
> -	ret = gpt_get_mdata_partitions(desc, mdata_parts);
>
> +	ret = gpt_get_mdata_partitions(desc);
>  	if (ret < 0) {
>  		log_debug("Error getting the FWU metadata partitions\n");
>  		return -ENOENT;
>  	}
>
> -	ret = gpt_read_write_mdata(desc, mdata, MDATA_READ, mdata_parts[0]);
> +	ret = gpt_read_write_mdata(desc, mdata, MDATA_READ, g_mdata_part[0]);
>  	if (ret < 0) {
>  		log_debug("Failed to read the FWU metadata from the device\n");
>  		return -EIO;
> @@ -182,7 +181,7 @@ static int gpt_get_mdata(struct blk_desc *desc, struct fwu_mdata *mdata)
>  	 * Try to read the replica.
>  	 */
>  	memset(mdata, '\0', sizeof(struct fwu_mdata));
> -	ret = gpt_read_write_mdata(desc, mdata, MDATA_READ, mdata_parts[1]);
> +	ret = gpt_read_write_mdata(desc, mdata, MDATA_READ, g_mdata_part[1]);
>  	if (ret < 0) {
>  		log_debug("Failed to read the FWU metadata from the device\n");
>  		return -EIO;
> @@ -206,9 +205,15 @@ static int fwu_gpt_get_mdata(struct udevice *dev, struct fwu_mdata *mdata)
>  static int fwu_gpt_get_mdata_partitions(struct udevice *dev, uint *mdata_parts)
>  {
>  	struct fwu_mdata_gpt_blk_priv *priv = dev_get_priv(dev);
> +	int err;
> +
> +	err = gpt_get_mdata_partitions(dev_get_uclass_plat(priv->blk_dev));
> +	if (!err) {
> +		mdata_parts[0] = g_mdata_part[0];
> +		mdata_parts[1] = g_mdata_part[1];
> +	}
>
> -	return gpt_get_mdata_partitions(dev_get_uclass_plat(priv->blk_dev),
> -					mdata_parts);
> +	return err;
>  }
>
>  static int fwu_gpt_read_mdata_partition(struct udevice *dev,
> --
> 2.34.1
>

Thanks
/Ilias