Re: net-PA Semi: Deletion of unnecessary checks before the function call "pci_dev_put"
From: Julia Lawall
Date: Mon Dec 01 2014 - 15:35:04 EST
On Mon, 1 Dec 2014, Johannes Berg wrote:
> On Mon, 2014-12-01 at 02:34 +0100, SF Markus Elfring wrote:
> > > Some of those NULL pointer checks on input parameters may have been
> > > added subsequently to functions. So there may be older kernel versions
> > > out there in which those checks dont exists in some cases. If some of
> > > the now "cleaned up" code is backported to such a kernel chances are
> > > good that those missing checks are overseen. And then neither caller nor
> > > callee is doing the NULL pointer check.
> > I assume that a few backporters can tell you more about their corresponding
> > software development experiences.
> > http://www.do-not-panic.com/2014/04/automatic-linux-kernel-backporting-with-coccinelle.html
> In such cases we just provide an appropriate wrapper and replace callers
> of the original function by callers of the wrapper, typically with a
> So this kind of evolution is no problem for the (automated) backports
> using the backports project - although it can be difficult to detect
> such a thing is needed.
That is exactly the problem...
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