Re: [PATCH 1/6] mtd: afs: simplify partition parsing

Liviu Dudau
2019-01-31T17:13:39Z

Hi Linus,

On Mon, Jan 28, 2019 at 02:54:44PM +0100, Linus Walleij wrote:
> This simplifies the AFS partition parsing to make the code
> more straight-forward and readable.
>
> Before this patch the code tried to calculate the memory required
> to hold the partition info by adding up the sizes of the strings
> of the names and adding that to a single memory allocation,
> indexing the name pointers in front of the struct mtd_partition
> allocations so all allocated data was in one chunk.
>
> This is overzealous. Instead use kstrdup and bail out,
> kfree():ing the memory used for MTD partitions and names alike
> on the errorpath.
>
> In the process rename the index variable from idx to i.
>
> Cc: Ryan Harkin <ryan.harkin@linaro.org>
> Cc: Liviu Dudau <liviu.dudau@arm.com>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> drivers/mtd/parsers/afs.c | 67 +++++++++++++++++++--------------------

What kernel is this series based on? Current Torvalds' tree has the
afs.c file in drivers/mtd and not in drivers/mtd/parsers/. Is there a
patch that I'm missing moving things around?

Best regards,
Liviu

> 1 file changed, 32 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mtd/parsers/afs.c b/drivers/mtd/parsers/afs.c
> index 3679e1d22595..c489938cd665 100644
> --- a/drivers/mtd/parsers/afs.c
> +++ b/drivers/mtd/parsers/afs.c
> @@ -166,9 +166,9 @@ static int parse_afs_partitions(struct mtd_info *mtd,
> struct mtd_part_parser_data *data)
> {
> struct mtd_partition *parts;
> - u_int mask, off, idx, sz;
> + u_int mask, off, sz;
> int ret = 0;
> - char *str;
> + int i;
>
> /*
> * This is the address mask; we use this to mask off out of
> @@ -181,78 +181,75 @@ static int parse_afs_partitions(struct mtd_info *mtd,
> * partition information. We include in this the size of
> * the strings.
> */
> - for (idx = off = sz = 0; off < mtd->size; off += mtd->erasesize) {
> - struct image_info_v1 iis;
> + for (i = off = sz = 0; off < mtd->size; off += mtd->erasesize) {
> u_int iis_ptr, img_ptr;
>
> ret = afs_read_footer_v1(mtd, &img_ptr, &iis_ptr, off, mask);
> if (ret < 0)
> - break;
> + return ret;
> if (ret) {
> - ret = afs_read_iis_v1(mtd, &iis, iis_ptr);
> - if (ret < 0)
> - break;
> - if (ret == 0)
> - continue;
> -
> sz += sizeof(struct mtd_partition);
> - sz += strlen(iis.name) + 1;
> - idx += 1;
> + i += 1;
> }
> }
>
> - if (!sz)
> - return ret;
> + if (!i)
> + return 0;
>
> parts = kzalloc(sz, GFP_KERNEL);
> if (!parts)
> return -ENOMEM;
>
> - str = (char *)(parts + idx);
> -
> /*
> * Identify the partitions
> */
> - for (idx = off = 0; off < mtd->size; off += mtd->erasesize) {
> + for (i = off = 0; off < mtd->size; off += mtd->erasesize) {
> struct image_info_v1 iis;
> u_int iis_ptr, img_ptr;
>
> /* Read the footer. */
> ret = afs_read_footer_v1(mtd, &img_ptr, &iis_ptr, off, mask);
> if (ret < 0)
> - break;
> + goto out_free_parts;
> if (ret == 0)
> continue;
>
> /* Read the image info block */
> ret = afs_read_iis_v1(mtd, &iis, iis_ptr);
> if (ret < 0)
> - break;
> + goto out_free_parts;
> if (ret == 0)
> continue;
>
> - strcpy(str, iis.name);
> + parts[i].name = kstrdup(iis.name, GFP_KERNEL);
> + if (!parts[i].name) {
> + ret = -ENOMEM;
> + goto out_free_parts;
> + }
>
> - parts[idx].name = str;
> - parts[idx].size = (iis.length + mtd->erasesize - 1) & ~(mtd->erasesize - 1);
> - parts[idx].offset = img_ptr;
> - parts[idx].mask_flags = 0;
> + parts[i].size = (iis.length + mtd->erasesize - 1) & ~(mtd->erasesize - 1);
> + parts[i].offset = img_ptr;
> + parts[i].mask_flags = 0;
>
> printk(" mtd%d: at 0x%08x, %5lluKiB, %8u, %s\n",
> - idx, img_ptr, parts[idx].size / 1024,
> - iis.imageNumber, str);
> -
> - idx += 1;
> - str = str + strlen(iis.name) + 1;
> - }
> + i, img_ptr, parts[i].size / 1024,
> + iis.imageNumber, parts[i].name);
>
> - if (!idx) {
> - kfree(parts);
> - parts = NULL;
> + i += 1;
> }
>
> *pparts = parts;
> - return idx ? idx : ret;
> + return i;
> +
> +out_free_parts:
> + while (i >= 0) {
> + if (parts[i].name)
> + kfree(parts[i].name);
> + i--;
> + }
> + kfree(parts);
> + *pparts = NULL;
> + return ret;
> }
>
> static const struct of_device_id mtd_parser_afs_of_match_table[] = {
> --
> 2.20.1
>

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
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