On Mon, 2015-10-26 at 14:33 -0500, Nathan Fontenot wrote:
> Commit a030e1e4bbd085bbcfd0a23f8d355fcd41f39bed made a change to use
> kstrndup() instead of kmalloc() + strlcpy() in
> pseries_of_derive_parent()
> which introduces a subtle change in the parent path name generated.
> The kstrndup() routine will copy n characters followed by a
> terminating null,
> whereas strlcpy() will copy n-1 characters and add a terminating
> null.
Nice catch!
One comment below.
>
> This slight difference results in having a parent path that includes
> the
> trailing '/' character, i.e. "/cpus/" vs. "/cpus". This then causes
> the
> subsequent call to of_find_node_by_path() to fail, and in the case of
> DLPAR add operations, the DLPAR request fails.
>
> This patch reduces the total length of the string to copy in kstrndup
> by 1
> so we no longer copy the trailing '/'.
>
> Signed-off-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/pseries/of_helpers.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/of_helpers.c
> b/arch/powerpc/platforms/pseries/of_helpers.c
> index 4417afe..6d90378 100644
> --- a/arch/powerpc/platforms/pseries/of_helpers.c
> +++ b/arch/powerpc/platforms/pseries/of_helpers.c
> @@ -24,7 +24,7 @@ struct device_node *pseries_of_derive_parent(const
> char *path)
> return ERR_PTR(-EINVAL);
>
> if (tail > path + 1) {
> - parent_path = kstrndup(path, tail - path,
> GFP_KERNEL);
> + parent_path = kstrndup(path, (tail - 1) - path,
> GFP_KERNEL);
Since previous line has (tail > path + 1) which is equivalent to (tail
- 1 > path), can we amend both?
For example (might be better, but first comes to my mind)
const char *tail = kbasename(path) - 1;
...
if (tail > path) {
> if (!parent_path)
> return ERR_PTR(-ENOMEM);
> }
>
--
Andy Shevchenko <andriy.shevche...@linux.intel.com>
Intel Finland Oy
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