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SubjectRe: 9pfs double kfree
On Mon, Mar 06, 2006 at 12:56:03PM +0530, Balbir Singh wrote:
> On 3/6/06, David S. Miller <davem@davemloft.net> wrote:
> > From: Dave Jones <davej@redhat.com>
> > Date: Mon, 6 Mar 2006 02:04:58 -0500
> >
> > > (I wish we had a kfree variant that NULL'd the target when it was free'd)
> >
> > Excellent idea.
> > -
>
> Slab debugging should catch double frees, but it will not attract your
> attention till you see your dmesg log.

The vast majority of people never run with slab poisoning enabled
judging by the number of bugs it constantly turns up.

> kfree() will ignore NULL
> pointer, from the comments in kfree

*nod*, poisoning the ptr would be a better idea.

> May we could have such a variant under CONFIG_DEBUG_SLAB if we needed
> and also change the variant kfree to BUG_ON() a NULL pointer.

given the cost is just a ptr assignment in a slow path, I'd prefer
it was non-optional, otherwise it'll be as underused as the other
debugging options.

Dave

--
http://www.codemonkey.org.uk
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