Messages in this thread | | | Date | Mon, 19 Mar 2012 12:08:08 +0100 | From | Martin Schwidefsky <> | Subject | Re: [PATCH]s390/char/vmur.c: memory leak Fix in the driver |
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On Mon, 19 Mar 2012 11:37:44 +0100 Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
> On Mon, 19 Mar 2012 01:55:40 +0000 > "Chen, Dennis (SRDC SW)" <Dennis1.Chen@amd.com> 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@vger.kernel.org > > Cc: beattiem@uk.ibm.com; holzheu@de.ibm.com; munzert@de.ibm.com; linux390@de.ibm.com; linux-s390@vger.kernel.org; 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@amd.com > > --- 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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