[PATCH v2 20/45] net: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-06-25 20:32:42
Also in:
linux-arch, linux-pm, lkml, netdev
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Duyck <redacted> Cc: Cong Wang <redacted> Cc: Ben Hutchings <redacted> Cc: netdev@vger.kernel.org Signed-off-by: Srivatsa S. Bhat <redacted> --- 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();