> On May 7, 2025, at 4:43 PM, Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx> wrote: > > !-------------------------------------------------------------------| > CAUTION: External Email > > |-------------------------------------------------------------------! > > Jon Kohler wrote: >> Hoist rcu_dereference(tun->xdp_prog) out of tun_xdp_one, so that >> rcu_deference is called once during batch processing. > > I'm skeptical that this does anything. > > The compiler can inline tun_xdp_one and indeed seems to do so. And > then it can cache the read in a register if that is the best use of > a register. The thought here is that if a compiler decided to not-inline tun_xdp_one (perhaps it grew to big, or the compiler was being sassy), that the intent would simply be that this wants to be called once-and-only-once. This change just makes that intent more clear, and is a nice little cleanup. I’ve got a series that stacks on top of this that enables multi-buffer support and I can keep an eye on if that gets inlined or not. > >> >> No functional change intended. >> >> Signed-off-by: Jon Kohler <jon@xxxxxxxxxxx>
