[PATCH] vme: remove unneeded kfree

[PATCH] vme: remove unneeded kfree

[Ding Xiang]

put_device will call vme_dev_release to free vdev, kfree is
unnecessary here.

Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
---
 drivers/vme/vme.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/vme/vme.c b/drivers/vme/vme.c
index 92500f6..520a5f9 100644
--- a/drivers/vme/vme.c
+++ b/drivers/vme/vme.c
@@ -1890,7 +1890,6 @@ static int __vme_register_driver_bus(struct vme_driver *drv,
 
 err_reg:
 	put_device(&vdev->dev);
-	kfree(vdev);
 err_devalloc:
 	list_for_each_entry_safe(vdev, tmp, &drv->devices, drv_list) {
 		list_del(&vdev->drv_list);
-- 
1.9.1

Re: [PATCH] vme: remove unneeded kfree

[Linus Torvalds]

On Thu, Sep 6, 2018 at 1:51 AM Ding Xiang
<dingxiang@cmss.chinamobile.com> wrote:
>
> put_device will call vme_dev_release to free vdev, kfree is
> unnecessary here.

That does seem to be the case.  I think "unnecessary" is overly kind,
it does seem to be a double free.

Looks like the issue was introduced back in 2013 by commit
def1820d25fa ("vme: add missing put_device() after device_register()
fails").

It seems you should *either* kfree() the vdev, _or_ do put_device(),
but doing both seems wrong.

I presume the device_register() has never failed, and this being
vme-only I'm guessing there isn't a vibrant testing community.

Greg?

              Linus

Re: [PATCH] vme: remove unneeded kfree

[Greg Kroah-Hartman]

On Thu, Sep 06, 2018 at 10:04:49PM -0700, Linus Torvalds wrote:
> On Thu, Sep 6, 2018 at 1:51 AM Ding Xiang
> <dingxiang@cmss.chinamobile.com> wrote:
> >
> > put_device will call vme_dev_release to free vdev, kfree is
> > unnecessary here.
> 
> That does seem to be the case.  I think "unnecessary" is overly kind,
> it does seem to be a double free.
> 
> Looks like the issue was introduced back in 2013 by commit
> def1820d25fa ("vme: add missing put_device() after device_register()
> fails").
> 
> It seems you should *either* kfree() the vdev, _or_ do put_device(),
> but doing both seems wrong.

You should only ever call put_device() after you have created the
structure, the documentation should say that somewhere...

> I presume the device_register() has never failed, and this being
> vme-only I'm guessing there isn't a vibrant testing community.
> 
> Greg?

It's the correct fix, I'll queue it up soon, thanks.

greg k-h

Re: [PATCH] vme: remove unneeded kfree

[Martyn Welch]

On Thu, 2018-09-06 at 22:04 -0700, Linus Torvalds wrote:
> On Thu, Sep 6, 2018 at 1:51 AM Ding Xiang
> <dingxiang@cmss.chinamobile.com> wrote:
> > 
> > put_device will call vme_dev_release to free vdev, kfree is
> > unnecessary here.
> 
> That does seem to be the case.  I think "unnecessary" is overly kind,
> it does seem to be a double free.
> 
> Looks like the issue was introduced back in 2013 by commit
> def1820d25fa ("vme: add missing put_device() after device_register()
> fails").
> 
> It seems you should *either* kfree() the vdev, _or_ do put_device(),
> but doing both seems wrong.
> 
> I presume the device_register() has never failed, and this being
> vme-only I'm guessing there isn't a vibrant testing community.
> 

I think that is also overly kind :-)

I currently lack access to suitable hardware to test fully myself and I
need to find some time to (re)implement some automated testing, after I
lost access to the bits I had when I left a previous employer. That and
see if I can get access to some hardware again...

Manohar, do you still have access/interest in the VME stuff? You've
been very quiet for a long time now.

Martyn