On Mon, 19 Mar 2012 11:37:44 +0100
Martin Schwidefsky <schwidefsky@xxxxxxxxxx> wrote:
> On Mon, 19 Mar 2012 01:55:40 +0000
> "Chen, Dennis (SRDC SW)" <Dennis1.Chen@xxxxxxx> wrote:
>
> > CC'ing maintainer: Martin Schwidefsky & Heiko Carstens...
> >
> > -----Original Message-----
> > From: Chen, Dennis (SRDC SW)
> > Sent: Sunday, March 18, 2012 3:41 AM
> > To: linux-kernel@xxxxxxxxxxxxxxx
> > Cc: beattiem@xxxxxxxxxx; holzheu@xxxxxxxxxx; munzert@xxxxxxxxxx; linux390@xxxxxxxxxx; linux-s390@xxxxxxxxxxxxxxx; Chen, Dennis (SRDC SW)
> > Subject: [PATCH]s390/char/vmur.c: memory leak Fix in the driver
> >
> > This patch is used to fix a memory leak issue in s390/char/vmur.c: a character device instance is
> > allocated by cdev_alloc, the cdev_del will not free that space if cdev_init is applied before.
> >
> > Signed-off-by: dennis1.chen@xxxxxxx
> > --- a/s390/char/vmur.c 2012-03-18 02:50:47.950963949 +0800
> > +++ b/s390/char/vmur.c 2012-03-18 03:12:04.790936740 +0800
> > @@ -903,7 +903,7 @@ static int ur_set_online(struct ccw_devi
> > goto fail_urdev_put;
> > }
> >
> > - cdev_init(urd->char_device, &ur_fops);
> > + urd->char_device->ops = &ur_fops;
> > urd->char_device->dev = MKDEV(major, minor);
> > urd->char_device->owner = ur_fops.owner;
> >
>
> How does that fix anything? My copy of cdev_init looks like this:
>
> void cdev_init(struct cdev *cdev, const struct file_operations *fops)
> {
> memset(cdev, 0, sizeof *cdev);
> INIT_LIST_HEAD(&cdev->list);
> kobject_init(&cdev->kobj, &ktype_cdev_default);
> cdev->ops = fops;
> }
>
> It does not allocate anything but it initializes some more fields.
> The new code would only initialize the ops field. In addition
> cdev_del does a kobject_put and the release function of the object
> will call cdev_dynamic_release as far as I can tell. That code
> should be fine as it is.
Hmm, forget that. cdev_init has a second kobject_init that replaces
ktype_cdev_dynamic with ktype_cdev_default. cdev_alloc already does
the initialization and your fix is just fine.
Seems like cdev_init is only there for static cdev structures.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
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