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author | Julian Anastasov <ja@ssi.bg> | 2015-07-09 09:59:10 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-07-10 18:16:36 -0700 |
commit | 2c17d27c36dcce2b6bf689f41a46b9e909877c21 (patch) | |
tree | 8868fe137839c66fcef2a435d8d1b38fd0cd7533 /net | |
parent | e9e4dd3267d0c5234c5c0f47440456b10875dec9 (diff) | |
download | linux-stable-2c17d27c36dcce2b6bf689f41a46b9e909877c21.tar.gz linux-stable-2c17d27c36dcce2b6bf689f41a46b9e909877c21.tar.bz2 linux-stable-2c17d27c36dcce2b6bf689f41a46b9e909877c21.zip |
net: call rcu_read_lock early in process_backlog
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>
Diffstat (limited to 'net')
-rw-r--r-- | net/core/dev.c | 32 |
1 files changed, 16 insertions, 16 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 6dd126a69aa0..a8e4dd430285 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3774,8 +3774,6 @@ 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; @@ -3785,7 +3783,7 @@ another_round: skb->protocol == cpu_to_be16(ETH_P_8021AD)) { skb = skb_vlan_untag(skb); if (unlikely(!skb)) - goto unlock; + goto out; } #ifdef CONFIG_NET_CLS_ACT @@ -3815,10 +3813,10 @@ skip_taps: if (static_key_false(&ingress_needed)) { skb = handle_ing(skb, &pt_prev, &ret, orig_dev); if (!skb) - goto unlock; + goto out; if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0) - goto unlock; + goto out; } #endif #ifdef CONFIG_NET_CLS_ACT @@ -3836,7 +3834,7 @@ 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); @@ -3848,7 +3846,7 @@ 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: @@ -3902,8 +3900,7 @@ drop: ret = NET_RX_DROP; } -unlock: - rcu_read_unlock(); +out: return ret; } @@ -3934,29 +3931,30 @@ static int __netif_receive_skb(struct sk_buff *skb) static int netif_receive_skb_internal(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; } /** @@ -4501,8 +4499,10 @@ static int process_backlog(struct napi_struct *napi, int quota) struct sk_buff *skb; 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) { |