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authorEric Dumazet <eric.dumazet@gmail.com>2010-04-15 11:14:07 +0400
committerDavid S. Miller <davem@davemloft.net>2010-04-15 11:14:07 +0400
commitb0e28f1effd1d840b36e961edc1def81e01b1ca1 (patch)
tree41e4299d3039dda9e3977c1a8625d09554e6fe4e /net/core/dev.c
parentfea069152614cdeefba4b2bf80afcddb9c217fc8 (diff)
downloadlinux-b0e28f1effd1d840b36e961edc1def81e01b1ca1.tar.xz
net: netif_rx() must disable preemption
Eric Paris reported netif_rx() is calling smp_processor_id() from preemptible context, in particular when caller is ip_dev_loopback_xmit(). RPS commit added this smp_processor_id() call, this patch makes sure preemption is disabled. rps_get_cpus() wants rcu_read_lock() anyway, we can dot it a bit earlier. Reported-by: Eric Paris <eparis@redhat.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
-rw-r--r--net/core/dev.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 876b1112d5ba..e8041eb76ac1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2206,6 +2206,7 @@ DEFINE_PER_CPU(struct netif_rx_stats, netdev_rx_stat) = { 0, };
/*
* get_rps_cpu is called from netif_receive_skb and returns the target
* CPU from the RPS map of the receiving queue for a given skb.
+ * rcu_read_lock must be held on entry.
*/
static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb)
{
@@ -2217,8 +2218,6 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb)
u8 ip_proto;
u32 addr1, addr2, ports, ihl;
- rcu_read_lock();
-
if (skb_rx_queue_recorded(skb)) {
u16 index = skb_get_rx_queue(skb);
if (unlikely(index >= dev->num_rx_queues)) {
@@ -2296,7 +2295,6 @@ got_hash:
}
done:
- rcu_read_unlock();
return cpu;
}
@@ -2392,7 +2390,7 @@ enqueue:
int netif_rx(struct sk_buff *skb)
{
- int cpu;
+ int ret;
/* if netpoll wants it, pretend we never saw it */
if (netpoll_rx(skb))
@@ -2402,14 +2400,21 @@ int netif_rx(struct sk_buff *skb)
net_timestamp(skb);
#ifdef CONFIG_RPS
- cpu = get_rps_cpu(skb->dev, skb);
- if (cpu < 0)
- cpu = smp_processor_id();
+ {
+ int cpu;
+
+ rcu_read_lock();
+ cpu = get_rps_cpu(skb->dev, skb);
+ if (cpu < 0)
+ cpu = smp_processor_id();
+ ret = enqueue_to_backlog(skb, cpu);
+ rcu_read_unlock();
+ }
#else
- cpu = smp_processor_id();
+ ret = enqueue_to_backlog(skb, get_cpu());
+ put_cpu();
#endif
-
- return enqueue_to_backlog(skb, cpu);
+ return ret;
}
EXPORT_SYMBOL(netif_rx);