From patchwork Tue Jun 25 20:29:02 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Srivatsa S. 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Bhat" Subject: [PATCH v2 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, "Srivatsa S. Bhat" Date: Wed, 26 Jun 2013 01:59:02 +0530 Message-ID: <20130625202901.16593.4774.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130625202452.16593.22810.stgit@srivatsabhat.in.ibm.com> References: <20130625202452.16593.22810.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062607-3568-0000-0000-000003D4B1AA Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-8.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html 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();