[U-Boot] [PATCH V3 2/8] disk: fix get_device_and_partition() bootable search

[Rob Herring <robherring2@gmail.com>]

On 09/18/2012 05:37 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren@nvidia.com>
> 
> The existing get_device_and_partition() bootable search loop attempts
> to save the current best known partition in variable best_part. However,
> it's actually just saving a copy of the (static) "info" variable, and
> hence ends up not doing anything much useful if no bootable partition
> is found. Fix this by reworking the loop to:
> 
> a) When reading information about a partition, always read into the
>    caller-supplied buffer; that way, if we find a bootable partition,
>    there's no need to copy any information.
> b) Save the first known valid partition's structure content rather than
>    pointer in the search loop, and restore the structure content rather
>    than the pointer when the loop exits.
> 
> Signed-off-by: Stephen Warren <swarren@nvidia.com>
> ---
> v3: New patch.

You might as well squash these into my original commits.

Rob

> ---
>  disk/part.c |   38 +++++++++++++++++++++++++++++---------
>  1 files changed, 29 insertions(+), 9 deletions(-)
> 
> diff --git a/disk/part.c b/disk/part.c
> index 6caf6d2..277a243 100644
> --- a/disk/part.c
> +++ b/disk/part.c
> @@ -447,7 +447,7 @@ int get_device_and_partition(const char *ifname, const char *dev_str,
>  	int p;
>  	int part = 0;
>  	char *part_str;
> -	disk_partition_t *best_part = NULL;
> +	disk_partition_t tmpinfo;
>  
>  	if (dev_str)
>  		dev = simple_strtoul(dev_str, &ep, 16);
> @@ -483,24 +483,44 @@ int get_device_and_partition(const char *ifname, const char *dev_str,
>  		part = (int)simple_strtoul(++part_str, NULL, 16);
>  		ret = get_partition_info(desc, part, info);
>  	} else {
> -		/* find the first bootable partition. If none are bootable,
> -		 * fall back to the first valid partition */
> +		/*
> +		 * Find the first bootable partition.
> +		 * If none are bootable, fall back to the first valid partition.
> +		 */
>  		for (p = 1; p <= MAX_SEARCH_PARTITIONS; p++) {
> -			ret = get_partition_info(desc, p, info);
> +			ret = get_partition_info(*dev_desc, p, info);
>  			if (ret)
>  				continue;
>  
> -			if (!best_part || info->bootable) {
> -				best_part = info;
> +			/*
> +			 * First valid partition, or new better partition?
> +			 * If so, save partition ID.
> +			 */
> +			if (!part || info->bootable)
>  				part = p;
> -			}
>  
> +			/* Best possible partition? Stop searching. */
>  			if (info->bootable)
>  				break;
> +
> +			/*
> +			 * We now need to search further for best possible.
> +			 * If we what we just queried was the best so far,
> +			 * save the info since we over-write it next loop.
> +			 */
> +			if (part == p)
> +				tmpinfo = *info;
>  		}
> -		info = best_part;
> -		if (part)
> +		/* If we found any acceptable partition */
> +		if (part) {
> +			/*
> +			 * If we searched all possible partition IDs,
> +			 * return the first valid partition we found.
> +			 */
> +			if (p == MAX_SEARCH_PARTITIONS + 1)
> +				*info = tmpinfo;
>  			ret = 0;
> +		}
>  	}
>  	if (ret) {
>  		printf("** Invalid partition %d, use `dev[:part]' **\n", part);
>