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authorEric Dumazet <edumazet@google.com>2013-08-08 08:06:14 -0700
committerDavid S. Miller <davem@davemloft.net>2013-08-11 21:48:58 -0700
commit29d7919692e591c2f0e1f743a7f6c613c1266ece (patch)
treef07046c3a4dd67f60becda844e1ab99174c38c86 /drivers/net
parente5ac5da8072104bed1749ffe64f2517f40416117 (diff)
downloadlinux-29d7919692e591c2f0e1f743a7f6c613c1266ece.tar.gz
macvtap: fix two races
Since commit ac4e4af1e59e1 ("macvtap: Consistently use rcu functions"), Thomas gets two different warnings : BUG: using smp_processor_id() in preemptible [00000000] code: vhost-45891/45892 caller is macvtap_do_read+0x45c/0x600 [macvtap] CPU: 1 PID: 45892 Comm: vhost-45891 Not tainted 3.11.0-bisecttest #13 Call Trace: ([<00000000001126ee>] show_trace+0x126/0x144) [<00000000001127d2>] show_stack+0xc6/0xd4 [<000000000068bcec>] dump_stack+0x74/0xd8 [<0000000000481066>] debug_smp_processor_id+0xf6/0x114 [<000003ff802e9a18>] macvtap_do_read+0x45c/0x600 [macvtap] [<000003ff802e9c1c>] macvtap_recvmsg+0x60/0x88 [macvtap] [<000003ff80318c5e>] handle_rx+0x5b2/0x800 [vhost_net] [<000003ff8028f77c>] vhost_worker+0x15c/0x1c4 [vhost] [<000000000015f3ac>] kthread+0xd8/0xe4 [<00000000006934a6>] kernel_thread_starter+0x6/0xc [<00000000006934a0>] kernel_thread_starter+0x0/0xc And BUG: using smp_processor_id() in preemptible [00000000] code: vhost-45897/45898 caller is macvlan_start_xmit+0x10a/0x1b4 [macvlan] CPU: 1 PID: 45898 Comm: vhost-45897 Not tainted 3.11.0-bisecttest #16 Call Trace: ([<00000000001126ee>] show_trace+0x126/0x144) [<00000000001127d2>] show_stack+0xc6/0xd4 [<000000000068bdb8>] dump_stack+0x74/0xd4 [<0000000000481132>] debug_smp_processor_id+0xf6/0x114 [<000003ff802b72ca>] macvlan_start_xmit+0x10a/0x1b4 [macvlan] [<000003ff802ea69a>] macvtap_get_user+0x982/0xbc4 [macvtap] [<000003ff802ea92a>] macvtap_sendmsg+0x4e/0x60 [macvtap] [<000003ff8031947c>] handle_tx+0x494/0x5ec [vhost_net] [<000003ff8028f77c>] vhost_worker+0x15c/0x1c4 [vhost] [<000000000015f3ac>] kthread+0xd8/0xe4 [<000000000069356e>] kernel_thread_starter+0x6/0xc [<0000000000693568>] kernel_thread_starter+0x0/0xc 2 locks held by vhost-45897/45898: #0: (&vq->mutex){+.+.+.}, at: [<000003ff8031903c>] handle_tx+0x54/0x5ec [vhost_net] #1: (rcu_read_lock){.+.+..}, at: [<000003ff802ea53c>] macvtap_get_user+0x824/0xbc4 [macvtap] In the first case, macvtap_put_user() calls macvlan_count_rx() in a preempt-able context, and this is not allowed. In the second case, macvtap_get_user() calls macvlan_start_xmit() with BH enabled, and this is not allowed. Reported-by: Thomas Huth <thuth@linux.vnet.ibm.com> Bisected-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Tested-by: Thomas Huth <thuth@linux.vnet.ibm.com> Cc: Vlad Yasevich <vyasevic@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/macvtap.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index a98fb0ed6aef..b51db2abfe44 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -818,10 +818,13 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
}
- if (vlan)
+ if (vlan) {
+ local_bh_disable();
macvlan_start_xmit(skb, vlan->dev);
- else
+ local_bh_enable();
+ } else {
kfree_skb(skb);
+ }
rcu_read_unlock();
return total_len;
@@ -912,8 +915,11 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
done:
rcu_read_lock();
vlan = rcu_dereference(q->vlan);
- if (vlan)
+ if (vlan) {
+ preempt_disable();
macvlan_count_rx(vlan, copied - vnet_hdr_len, ret == 0, 0);
+ preempt_enable();
+ }
rcu_read_unlock();
return ret ? ret : copied;