From: David Howells Date: Tue, 20 Apr 2010 00:25:58 +0000 (+0000) Subject: net: Fix an RCU warning in dev_pick_tx() X-Git-Tag: firefly_0821_release~9833^2~2199^2~67 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=05d17608a69b3ae653ea5c9857283bef3439c733;p=firefly-linux-kernel-4.4.55.git net: Fix an RCU warning in dev_pick_tx() Fix the following RCU warning in dev_pick_tx(): =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- net/core/dev.c:1993 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 2 locks held by swapper/0: #0: (&idev->mc_ifc_timer){+.-...}, at: [] run_timer_softirq+0x17b/0x278 #1: (rcu_read_lock_bh){.+....}, at: [] dev_queue_xmit+0x14e/0x4dc stack backtrace: Pid: 0, comm: swapper Not tainted 2.6.34-rc5-cachefs #4 Call Trace: [] lockdep_rcu_dereference+0xaa/0xb2 [] dev_queue_xmit+0x259/0x4dc [] ? dev_queue_xmit+0x14e/0x4dc [] ? trace_hardirqs_on+0xd/0xf [] ? local_bh_enable_ip+0xbc/0xc1 [] neigh_resolve_output+0x24b/0x27c [] ip6_output_finish+0x7c/0xb4 [] ip6_output2+0x256/0x261 [] ? trace_hardirqs_on+0xd/0xf [] ip6_output+0xbbc/0xbcb [] ? fib6_force_start_gc+0x2b/0x2d [] mld_sendpack+0x273/0x39d [] ? mld_sendpack+0x0/0x39d [] ? mark_held_locks+0x52/0x70 [] mld_ifc_timer_expire+0x24f/0x288 [] run_timer_softirq+0x1ec/0x278 [] ? run_timer_softirq+0x17b/0x278 [] ? mld_ifc_timer_expire+0x0/0x288 [] ? __do_softirq+0x69/0x140 [] __do_softirq+0xa2/0x140 [] call_softirq+0x1c/0x28 [] do_softirq+0x38/0x80 [] irq_exit+0x45/0x47 [] smp_apic_timer_interrupt+0x88/0x96 [] apic_timer_interrupt+0x13/0x20 [] ? __atomic_notifier_call_chain+0x0/0x86 [] ? mwait_idle+0x6e/0x78 [] ? mwait_idle+0x65/0x78 [] cpu_idle+0x4d/0x83 [] rest_init+0xb9/0xc0 [] ? rest_init+0x0/0xc0 [] start_kernel+0x392/0x39d [] x86_64_start_reservations+0xb3/0xb7 [] x86_64_start_kernel+0xe4/0xeb An rcu_dereference() should be an rcu_dereference_bh(). Signed-off-by: David Howells Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/net/core/dev.c b/net/core/dev.c index 92584bfef09b..f769098774b7 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1990,7 +1990,7 @@ static struct netdev_queue *dev_pick_tx(struct net_device *dev, queue_index = skb_tx_hash(dev, skb); if (sk) { - struct dst_entry *dst = rcu_dereference(sk->sk_dst_cache); + struct dst_entry *dst = rcu_dereference_bh(sk->sk_dst_cache); if (dst && skb_dst(skb) == dst) sk_tx_queue_set(sk, queue_index);