Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752547Ab3FWNqI (ORCPT ); Sun, 23 Jun 2013 09:46:08 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:53875 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752053Ab3FWNqA (ORCPT ); Sun, 23 Jun 2013 09:46:00 -0400 From: "Srivatsa S. Bhat" Subject: [PATCH 20/45] net: Use get/put_online_cpus_atomic() to prevent CPU offline To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" , Eric Dumazet , Alexander Duyck , Cong Wang , Ben Hutchings , netdev@vger.kernel.org Date: Sun, 23 Jun 2013 19:12:40 +0530 Message-ID: <20130623134236.19094.39650.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> References: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062313-2000-0000-0000-00000C9A1C3E Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2531 Lines: 83 Once stop_machine() is gone from the CPU offline path, we won't be able to depend on disabling preemption to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Alexander Duyck Cc: Cong Wang Cc: Ben Hutchings Cc: netdev@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- net/core/dev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index fc1e289..90519e9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3141,7 +3141,7 @@ int netif_rx(struct sk_buff *skb) struct rps_dev_flow voidflow, *rflow = &voidflow; int cpu; - preempt_disable(); + get_online_cpus_atomic(); rcu_read_lock(); cpu = get_rps_cpu(skb->dev, skb, &rflow); @@ -3151,7 +3151,7 @@ int netif_rx(struct sk_buff *skb) ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail); rcu_read_unlock(); - preempt_enable(); + put_online_cpus_atomic(); } else #endif { @@ -3570,6 +3570,7 @@ int netif_receive_skb(struct sk_buff *skb) struct rps_dev_flow voidflow, *rflow = &voidflow; int cpu, ret; + get_online_cpus_atomic(); rcu_read_lock(); cpu = get_rps_cpu(skb->dev, skb, &rflow); @@ -3577,9 +3578,11 @@ int netif_receive_skb(struct sk_buff *skb) if (cpu >= 0) { ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail); rcu_read_unlock(); + put_online_cpus_atomic(); return ret; } rcu_read_unlock(); + put_online_cpus_atomic(); } #endif return __netif_receive_skb(skb); @@ -3957,6 +3960,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd) local_irq_enable(); /* Send pending IPI's to kick RPS processing on remote cpus. */ + get_online_cpus_atomic(); while (remsd) { struct softnet_data *next = remsd->rps_ipi_next; @@ -3965,6 +3969,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd) &remsd->csd, 0); remsd = next; } + put_online_cpus_atomic(); } else #endif local_irq_enable(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/