On Tue, Dec 11, 2018 at 11:43:07AM +0900, Prashant Bhole wrote: > tun_xdp_one() runs with local bh disabled. So there is no need to > disable preemption by calling get_cpu_ptr while updating stats. This > patch replaces the use of get_cpu_ptr() with this_cpu_ptr() as a > micro-optimization. Also removes related put_cpu_ptr call. > > Acked-by: Jason Wang <jasow...@redhat.com> > Signed-off-by: Prashant Bhole <bhole_prashant...@lab.ntt.co.jp>
Acked-by: Michael S. Tsirkin <m...@redhat.com> > --- > v1 -> v2: Added comment to explain why this change is safe > > drivers/net/tun.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 6760b86547df..cb90859d0433 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -2494,12 +2494,14 @@ static int tun_xdp_one(struct tun_struct *tun, > skb_record_rx_queue(skb, tfile->queue_index); > netif_receive_skb(skb); > > - stats = get_cpu_ptr(tun->pcpu_stats); > + /* No need for get_cpu_ptr() here since this function is > + * always called with bh disabled > + */ > + stats = this_cpu_ptr(tun->pcpu_stats); > u64_stats_update_begin(&stats->syncp); > stats->rx_packets++; > stats->rx_bytes += skb->len; > u64_stats_update_end(&stats->syncp); > - put_cpu_ptr(stats); > > if (rxhash) > tun_flow_update(tun, rxhash, tfile); > -- > 2.17.2 >
