Re: [PATCH v2 1/2] MIPS: vpe-mt: fix possible memory leak while module exiting

[Thomas Bogendoerfer <tsbogend@alpha.franken.de>]

On Tue, Nov 22, 2022 at 07:41:26PM +0800, Yang Yingliang wrote:
> Hi,
> 
> On 2022/11/22 19:21, Thomas Bogendoerfer wrote:
> > On Fri, Nov 04, 2022 at 11:39:44AM +0800, Yang Yingliang wrote:
> > > Afer commit 1fa5ae857bb1 ("driver core: get rid of struct device's
> > > bus_id string array"), the name of device is allocated dynamically,
> > > it need be freed when module exiting, call put_device() to give up
> > > reference, so that it can be freed in kobject_cleanup() when the
> > > refcount hit to 0. The vpe_device is static, so remove kfree() from
> > > vpe_device_release().
> > > 
> > > Fixes: 1fa5ae857bb1 ("driver core: get rid of struct device's bus_id string array")
> > > Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> > > ---
> > >   arch/mips/kernel/vpe-mt.c | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/arch/mips/kernel/vpe-mt.c b/arch/mips/kernel/vpe-mt.c
> > > index bad6b0891b2b..84a82b551ec3 100644
> > > --- a/arch/mips/kernel/vpe-mt.c
> > > +++ b/arch/mips/kernel/vpe-mt.c
> > > @@ -313,7 +313,6 @@ ATTRIBUTE_GROUPS(vpe);
> > >   static void vpe_device_release(struct device *cd)
> > >   {
> > > -	kfree(cd);
> > >   }
> > as this is empty now, we can IMHO remove the function completly. Same
> > for the other patch in this series.
> It can not be removed, or it will cause WARNING in device_release() when
> calling
> put_device()/device_unregister().
> 
> static void device_release(struct kobject *kobj)
> {
> ...
> 
>         if (dev->release)
>                 dev->release(dev);
>         else if (dev->type && dev->type->release)
>                 dev->type->release(dev);
>         else if (dev->class && dev->class->dev_release)
>                 dev->class->dev_release(dev);
>         else
>                 WARN(1, KERN_ERR "Device '%s' does not have a release()
> function, it is broken and must be fixed. See
> Documentation/core-api/kobject.rst.\n",
>                         dev_name(dev));  // WANING here

you are right, thank you for looking into that,

Thomas.

-- 
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