Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932159AbdCTVtV (ORCPT ); Mon, 20 Mar 2017 17:49:21 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:35535 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756004AbdCTVsu (ORCPT ); Mon, 20 Mar 2017 17:48:50 -0400 Subject: [net-next PATCH 1/2] net: Busy polling should ignore sender CPUs From: Alexander Duyck To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: sridhar.samudrala@intel.com, edumazet@google.com, davem@davemloft.net Date: Mon, 20 Mar 2017 14:48:48 -0700 Message-ID: <20170320214848.13922.79201.stgit@localhost.localdomain> In-Reply-To: <20170320214643.13922.51284.stgit@localhost.localdomain> References: <20170320214643.13922.51284.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2363 Lines: 67 From: Alexander Duyck This patch is a cleanup/fix for NAPI IDs following the changes that made it so that sender_cpu and napi_id were doing a better job of sharing the same location in the sk_buff. One issue I found is that we weren't validating the napi_id as being valid before we started trying to setup the busy polling. This change corrects that by using the MIN_NAPI_ID value that is now used in both allocating the NAPI IDs, as well as validating them. Fixes: 52bd2d62ce675 ("net: better skb->sender_cpu and skb->napi_id cohabitation") Signed-off-by: Alexander Duyck --- include/net/busy_poll.h | 11 +++++++++-- net/core/dev.c | 6 +++--- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index c0452de83086..edf1310212a1 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -35,6 +35,12 @@ extern unsigned int sysctl_net_busy_read __read_mostly; extern unsigned int sysctl_net_busy_poll __read_mostly; +/* 0 - Reserved to indicate value not set + * 1..NR_CPUS - Reserved for sender_cpu + * NR_CPUS+1..~0 - Region available for NAPI IDs + */ +#define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1)) + static inline bool net_busy_loop_on(void) { return sysctl_net_busy_poll; @@ -58,10 +64,11 @@ static inline unsigned long busy_loop_end_time(void) static inline bool sk_can_busy_loop(const struct sock *sk) { - return sk->sk_ll_usec && sk->sk_napi_id && !signal_pending(current); + return sk->sk_ll_usec && + (sk->sk_napi_id >= MIN_NAPI_ID) && + !signal_pending(current); } - static inline bool busy_loop_timeout(unsigned long end_time) { unsigned long now = busy_loop_us_clock(); diff --git a/net/core/dev.c b/net/core/dev.c index 7869ae3837ca..5bbe30c08a5b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5143,10 +5143,10 @@ static void napi_hash_add(struct napi_struct *napi) spin_lock(&napi_hash_lock); - /* 0..NR_CPUS+1 range is reserved for sender_cpu use */ + /* 0..NR_CPUS range is reserved for sender_cpu use */ do { - if (unlikely(++napi_gen_id < NR_CPUS + 1)) - napi_gen_id = NR_CPUS + 1; + if (unlikely(++napi_gen_id < MIN_NAPI_ID)) + napi_gen_id = MIN_NAPI_ID; } while (napi_by_id(napi_gen_id)); napi->napi_id = napi_gen_id;