[U-Boot] [PATCH V3 2/8] disk: fix get_device_and_partition() bootable search
Rob Herring
robherring2 at gmail.com
Wed Sep 19 03:18:52 CEST 2012
On 09/18/2012 05:37 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren at 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 at 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);
>
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