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authorJulian Anastasov <ja@ssi.bg>2015-07-09 09:59:10 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-01 12:07:35 +0200
commitc987fa7146e0c18acc2392b25349cca45c177175 (patch)
tree560132838853a9ca5ebda120ddc88b170d7cafd4
parentf85eee641c7a3bb928a4b605db632c2e90b9574f (diff)
downloadlinux-linaro-stable-c987fa7146e0c18acc2392b25349cca45c177175.tar.gz
net: call rcu_read_lock early in process_backlog
[ Upstream commit 2c17d27c36dcce2b6bf689f41a46b9e909877c21 ] Incoming packet should be either in backlog queue or in RCU read-side section. Otherwise, the final sequence of flush_backlog() and synchronize_net() may miss packets that can run without device reference: CPU 1 CPU 2 skb->dev: no reference process_backlog:__skb_dequeue process_backlog:local_irq_enable on_each_cpu for flush_backlog => IPI(hardirq): flush_backlog - packet not found in backlog CPU delayed ... synchronize_net - no ongoing RCU read-side sections netdev_run_todo, rcu_barrier: no ongoing callbacks __netif_receive_skb_core:rcu_read_lock - too late free dev process packet for freed dev Fixes: 6e583ce5242f ("net: eliminate refcounting in backlog queue") Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/core/dev.c29
1 files changed, 14 insertions, 15 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index aeca8dd88b2a..1ccfc49683b3 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3443,8 +3443,6 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
pt_prev = NULL;
- rcu_read_lock();
-
another_round:
skb->skb_iif = skb->dev->ifindex;
@@ -3454,7 +3452,7 @@ another_round:
skb->protocol == cpu_to_be16(ETH_P_8021AD)) {
skb = vlan_untag(skb);
if (unlikely(!skb))
- goto unlock;
+ goto out;
}
#ifdef CONFIG_NET_CLS_ACT
@@ -3479,7 +3477,7 @@ skip_taps:
#ifdef CONFIG_NET_CLS_ACT
skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto unlock;
+ goto out;
ncls:
#endif
@@ -3494,7 +3492,7 @@ ncls:
if (vlan_do_receive(&skb))
goto another_round;
else if (unlikely(!skb))
- goto unlock;
+ goto out;
}
rx_handler = rcu_dereference(skb->dev->rx_handler);
@@ -3506,7 +3504,7 @@ ncls:
switch (rx_handler(&skb)) {
case RX_HANDLER_CONSUMED:
ret = NET_RX_SUCCESS;
- goto unlock;
+ goto out;
case RX_HANDLER_ANOTHER:
goto another_round;
case RX_HANDLER_EXACT:
@@ -3558,8 +3556,6 @@ drop:
ret = NET_RX_DROP;
}
-unlock:
- rcu_read_unlock();
out:
return ret;
}
@@ -3606,29 +3602,30 @@ static int __netif_receive_skb(struct sk_buff *skb)
*/
int netif_receive_skb(struct sk_buff *skb)
{
+ int ret;
+
net_timestamp_check(netdev_tstamp_prequeue, skb);
if (skb_defer_rx_timestamp(skb))
return NET_RX_SUCCESS;
+ rcu_read_lock();
+
#ifdef CONFIG_RPS
if (static_key_false(&rps_needed)) {
struct rps_dev_flow voidflow, *rflow = &voidflow;
- int cpu, ret;
-
- rcu_read_lock();
-
- cpu = get_rps_cpu(skb->dev, skb, &rflow);
+ int cpu = get_rps_cpu(skb->dev, skb, &rflow);
if (cpu >= 0) {
ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
rcu_read_unlock();
return ret;
}
- rcu_read_unlock();
}
#endif
- return __netif_receive_skb(skb);
+ ret = __netif_receive_skb(skb);
+ rcu_read_unlock();
+ return ret;
}
EXPORT_SYMBOL(netif_receive_skb);
@@ -4038,8 +4035,10 @@ static int process_backlog(struct napi_struct *napi, int quota)
unsigned int qlen;
while ((skb = __skb_dequeue(&sd->process_queue))) {
+ rcu_read_lock();
local_irq_enable();
__netif_receive_skb(skb);
+ rcu_read_unlock();
local_irq_disable();
input_queue_head_incr(sd);
if (++work >= quota) {