[PATCH] net/af_packet: fix statistics

[Stephen Hemminger]

On Wed, 1 May 2024 17:25:59 +0100
Ferruh Yigit <ferruh.yigit at amd.com> wrote:

> >  - Do not mark statistics as volatile.
> >    Instead, READ_ONCE() where necessary.
> >   
> 
> I did similar [1], and Mattias has some comments on it.
> Issue is not in the reader (stats_get) side. Without volatile writer
> (datapath thread) may end up *not* storing updated stats to memory.
> 
> For reader side, I expect value not been in the register when function
> called, so it ends up reading from memory, which doesn't require
> volatile casting.

These are per-queue stats, and anybody foolish enough to have multiple
threads sharing same queue without locking is playing with fire.
It is documented that DPDK PMD's don't support that.