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Bhat" Subject: [PATCH v5 19/45] 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 Date: Tue, 22 Jan 2013 13:08:21 +0530 Message-ID: <20130122073817.13822.60227.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13012207-7014-0000-0000-0000027FF877 Cc: linux-arch@vger.kernel.org, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, fweisbec@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, wangyun@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() 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: 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 f64e439..5421f96 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3089,7 +3089,7 @@ 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); @@ -3099,7 +3099,7 @@ 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 { @@ -3498,6 +3498,7 @@ 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); @@ -3505,9 +3506,11 @@ 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); @@ -3887,6 +3890,7 @@ 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; @@ -3895,6 +3899,7 @@ 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();