On Fri, May 31, 2019 at 08:45:47AM -0700, Eric Dumazet wrote:

On 5/31/19 7:45 AM, Herbert Xu wrote:

quoted

In this case the code doesn't need them because an implicit
barrier() (which is *stronger* than READ_ONCE/WRITE_ONCE) already
exists in both places.

I have already explained that the READ_ONCE() was a leftover of the first version
of the patch, that I refined later, adding correct (and slightly more complex) RCU
barriers and rules.

AFAICT, neither barrier() nor RCU synchronization can be used as
a replacement for {READ,WRITE}_ONCE() here (and in tons of other
different situations).  IOW, you might want to try harder.  ;-)

Thanks,
  Andrea