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SubjectRe: [PATCH] driver: dont update dev_name if it is not changed

* Yinghai Lu <yinghai@kernel.org> wrote:

> Ingo Molnar wrote:
> > * Yinghai Lu <yinghai@kernel.org> wrote:
> >
> >> notice one system /proc/iomem some entries missed the name for pci_devices
> >>
> >> it turns that dev->dev.kobj name is changed after device_add.
> >>
> >> [Impact: fix corrupted names in /proc/iomem ]
> >>
> >> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> >>
> >> ---
> >> lib/kobject.c | 13 +++++++++++--
> >> 1 file changed, 11 insertions(+), 2 deletions(-)
> >>
> >> Index: linux-2.6/lib/kobject.c
> >> ===================================================================
> >> --- linux-2.6.orig/lib/kobject.c
> >> +++ linux-2.6/lib/kobject.c
> >> @@ -216,12 +216,21 @@ int kobject_set_name_vargs(struct kobjec
> >> va_list vargs)
> >> {
> >> const char *old_name = kobj->name;
> >> + char *new_name;
> >> char *s;
> >>
> >> - kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
> >> - if (!kobj->name)
> >> + new_name = kvasprintf(GFP_KERNEL, fmt, vargs);
> >> + if (!new_name)
> >> return -ENOMEM;
> >>
> >> + /* different ? */
> >> + if (!strcmp(new_name, old_name)) {
> >> + kfree(new_name);
> >> + return 0;
> >> + }
> >> +
> >> + kobj->name = new_name;
> >> +
> >> /* ewww... some of these buggers have '/' in the name ... */
> >> while ((s = strchr(kobj->name, '/')))
> >> s[0] = '!';
> >
> > So we used the old name in the resource code, and the kfree() here
> > corrupted the /proc/iomem output?
> >
> if it is not changed, we still use old_name. and new_name get freed

I know - you are talking about your patch.

But i'm talking about the current, unpatched upstream code. It got a
string displayed in /proc/iomem that got kfree()d? [and this is why
the entries vanished?]

That is badness somewhere _else_ (not in the kobject core i think),
and your patch does not solve the real badness, it works around its
symptoms AFAICS - like the first patch.

Ingo


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