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powerpc/pseries: Correct string length in pseries_of_derive_parent()

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Commit a030e1e4bb make a change to use
kstrndup() instead of kmalloc() + strlcpy() in the pseries_of_derive_parent()
routine that 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.

This slight difference results in having a parent path that includes the
tailing '/' character, "/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 decrements the pointer returned from kbasename() to point to the
'/' character before the base name instead of the base name. This then
adjusts the string length calculations to not include the trailing '/'
in the parent path name.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nathan Fontenot 2015-10-27 10:46:47 -05:00 committed by Michael Ellerman
parent 353169acf1
commit f755ecfb8c
1 changed files with 5 additions and 2 deletions
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7
arch/powerpc/platforms/pseries/of_helpers.c
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@ -17,13 +17,16 @@ struct device_node *pseries_of_derive_parent(const char *path)
{
struct device_node *parent;
char *parent_path = "/";
const char *tail = kbasename(path);
const char *tail;
/* We do not want the trailing '/' character */
tail = kbasename(path) - 1;
/* reject if path is "/" */
if (!strcmp(path, "/"))
return ERR_PTR(-EINVAL);
if (tail > path + 1) {
if (tail > path) {
parent_path = kstrndup(path, tail - path, GFP_KERNEL);
if (!parent_path)
return ERR_PTR(-ENOMEM);