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| author |   Jason Wang <jasowang@redhat.com> | 2019-05-08 23:20:18 -0400 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2019-05-09 09:21:42 -0700 |
| commit | 9871a9e47a2646fe30ae7fd2e67668a8d30912f6 (patch) | |
| tree | 06772218a11b4c05b06d31ed92c649cac61b6a8b /drivers/net/tun.c | |
| parent | tuntap: fix dividing by zero in ebpf queue selection (diff) | |
| download | linux-dev-9871a9e47a2646fe30ae7fd2e67668a8d30912f6.tar.xz linux-dev-9871a9e47a2646fe30ae7fd2e67668a8d30912f6.zip | |
tuntap: synchronize through tfiles array instead of tun->numqueues
When a queue(tfile) is detached through __tun_detach(), we move the
last enabled tfile to the position where detached one sit but don't
NULL out last position. We expect to synchronize the datapath through
tun->numqueues. Unfortunately, this won't work since we're lacking
sufficient mechanism to order or synchronize the access to
tun->numqueues.
To fix this, NULL out the last position during detaching and check
RCU protected tfile against NULL instead of checking tun->numqueues in
datapath.
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: weiyongjun (A) <weiyongjun1@huawei.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: c8d68e6be1c3b ("tuntap: multiqueue support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tun.c')
| -rw-r--r-- | drivers/net/tun.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index a52bd47e7aa2..abae165dcca5 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -704,6 +704,8 @@ static void __tun_detach(struct tun_file *tfile, bool clean) tun->tfiles[tun->numqueues - 1]); ntfile = rtnl_dereference(tun->tfiles[index]); ntfile->queue_index = index; + rcu_assign_pointer(tun->tfiles[tun->numqueues - 1], + NULL); --tun->numqueues; if (clean) { @@ -1086,7 +1088,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) tfile = rcu_dereference(tun->tfiles[txq]); /* Drop packet if interface is not attached */ - if (txq >= tun->numqueues) + if (!tfile) goto drop; if (!rcu_dereference(tun->steering_prog)) @@ -1309,6 +1311,7 @@ static int tun_xdp_xmit(struct net_device *dev, int n, rcu_read_lock(); +resample: numqueues = READ_ONCE(tun->numqueues); if (!numqueues) { rcu_read_unlock(); @@ -1317,6 +1320,8 @@ static int tun_xdp_xmit(struct net_device *dev, int n, tfile = rcu_dereference(tun->tfiles[smp_processor_id() % numqueues]); + if (unlikely(!tfile)) + goto resample; spin_lock(&tfile->tx_ring.producer_lock); for (i = 0; i < n; i++) { |