Re: [PATCH v2] powerpc/pseries: Correct string length in pseries_of_derive_parent()
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: 2015-10-27 15:54:58
On Tue, 2015-10-27 at 10:46 -0500, Nathan Fontenot wrote:
Commit a030e1e4bbd085bbcfd0a23f8d355fcd41f39bed 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 <redacted>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
quoted hunk ↗ jump to hunk
--- Updates for v2: Decrement the pointer returned from kbasename() instead of subtracting 1 when calculating the string length. arch/powerpc/platforms/pseries/of_helpers.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/arch/powerpc/platforms/pseries/of_helpers.cb/arch/powerpc/platforms/pseries/of_helpers.c index 4417afe..2798933 100644--- a/arch/powerpc/platforms/pseries/of_helpers.c +++ b/arch/powerpc/platforms/pseries/of_helpers.c@@ -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);
-- Andy Shevchenko [off-list ref] Intel Finland Oy