linux-kernel - Re: [PATCH 01/11] kset: fix documentation for kset

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Message-ID: <Y1JVWsLs0EQ3dtxM@kroah.com>
Date:   Fri, 21 Oct 2022 10:16:26 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Yang Yingliang <yangyingliang@...wei.com>
Cc:     Luben Tuikov <luben.tuikov@....com>, linux-kernel@...r.kernel.org,
        qemu-devel@...gnu.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-erofs@...ts.ozlabs.org, ocfs2-devel@....oracle.com,
        linux-mtd@...ts.infradead.org, amd-gfx@...ts.freedesktop.org,
        rafael@...nel.org, somlo@....edu, mst@...hat.com,
        jaegeuk@...nel.org, chao@...nel.org, hsiangkao@...ux.alibaba.com,
        huangjianan@...o.com, mark@...heh.com, jlbec@...lplan.org,
        joseph.qi@...ux.alibaba.com, akpm@...ux-foundation.org,
        alexander.deucher@....com, richard@....at, liushixin2@...wei.com
Subject: Re: [PATCH 01/11] kset: fix documentation for kset_register()

On Fri, Oct 21, 2022 at 04:05:18PM +0800, Yang Yingliang wrote:
> 
> On 2022/10/21 13:34, Luben Tuikov wrote:
> > On 2022-10-20 22:20, Yang Yingliang wrote:
> > > kset_register() is currently used in some places without calling
> > > kset_put() in error path, because the callers think it should be
> > > kset internal thing to do, but the driver core can not know what
> > > caller doing with that memory at times. The memory could be freed
> > > both in kset_put() and error path of caller, if it is called in
> > > kset_register().
> > > 
> > > So make the function documentation more explicit about calling
> > > kset_put() in the error path of caller.
> > > 
> > > Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
> > > ---
> > >   lib/kobject.c | 3 +++
> > >   1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/lib/kobject.c b/lib/kobject.c
> > > index a0b2dbfcfa23..6da04353d974 100644
> > > --- a/lib/kobject.c
> > > +++ b/lib/kobject.c
> > > @@ -834,6 +834,9 @@ EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
> > >   /**
> > >    * kset_register() - Initialize and add a kset.
> > >    * @k: kset.
> > > + *
> > > + * If this function returns an error, kset_put() must be called to
> > > + * properly clean up the memory associated with the object.
> > >    */
> > And I'd continue the sentence, with " ... with the object,
> > for instance the memory for the kset.kobj.name when kobj_set_name(&kset.kobj, format, ...)
> > was called before calling kset_register()."
> kobject_cleanup() not only frees name, but aslo calls ->release() to free
> another resources.

Yes, but it's the kobject of the kset, which does need to have it's name
cleaned up, but that kobject should NOT be freeing any larger structures
that the kset might be embedded in, right?

> > This makes it clear what we want to make sure is freed, in case of an early error
> > from kset_register().
> 
> How about like this:
> 
> If this function returns an error, kset_put() must be called to clean up the name of
> kset object and other memory associated with the object.

Again, I think we can fix this up to not be needed.

thanks,

greg k-h