Re: [PATCH 3/3] netfilter: x_tables: Use correct memory barriers.

[Mark Tomlinson]

On Thu, 2021-03-04 at 08:46 +0100, Florian Westphal wrote:
> Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx> wrote:
> > Changing to using smp_mb() instead of smp_wmb() fixes the kernel panic
> > reported in cc00bcaa5899,
> 
> Can you reproduce the crashes without this change?

Yes. In our test environment we were seeing a kernel panic approx. twice
a day, with a similar output to that shown in Subash's patch (cc00bcaa5899).
With this patch we are not seeing any issue. The CPU is a dual-core ARM
Cortex-A9.

> > How much of an impact is the MB change on the packet path?

I will run our throughput tests and get these results.

I have a script which makes around 200 calls to iptables. This was taking
11.59s and now is back to 1.16s.