Re: UBSAN reports issue in ip_idents_reserve

Tue, Sep 20, 2016 at 05:25:16PM CEST, eric.dumazet@gmail.com wrote:

On Tue, 2016-09-20 at 07:11 -0700, Eric Dumazet wrote:

quoted

On Tue, 2016-09-20 at 15:39 +0200, Jiri Pirko wrote:

quoted

I see. So how to silent the warning?

We can replace the atomic_add_return() and use a loop around
atomic_read() and atomic_cmpxhg()

This would change the nice property of x86 xadd into a loop.

Or we also could fallback to random generation if the atomic_cmpxchg()
fails.

I'll provide a patch, thanks.

I'm going to test your patch now.

I looks at other places, I am surprised you do not see other UBSAN
issues in networking :)

Not yet :)

netdev_refcnt_read() can potentially gives errors as well.