diff options
| author | Davide Caratti <dcaratti@redhat.com> | 2023-01-20 20:01:40 +0300 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2023-01-24 12:30:54 +0300 |
| commit | ca22da2fbd693b54dc8e3b7b54ccc9f7e9ba3640 (patch) | |
| tree | 18f1cb00edf54a2a8684e41be562bacf46839209 /net | |
| parent | 78dcdffe0418ac8f3f057f26fe71ccf4d8ed851f (diff) | |
| download | linux-ca22da2fbd693b54dc8e3b7b54ccc9f7e9ba3640.tar.xz | |
act_mirred: use the backlog for nested calls to mirred ingress
William reports kernel soft-lockups on some OVS topologies when TC mirred
egress->ingress action is hit by local TCP traffic [1].
The same can also be reproduced with SCTP (thanks Xin for verifying), when
client and server reach themselves through mirred egress to ingress, and
one of the two peers sends a "heartbeat" packet (from within a timer).
Enqueueing to backlog proved to fix this soft lockup; however, as Cong
noticed [2], we should preserve - when possible - the current mirred
behavior that counts as "overlimits" any eventual packet drop subsequent to
the mirred forwarding action [3]. A compromise solution might use the
backlog only when tcf_mirred_act() has a nest level greater than one:
change tcf_mirred_forward() accordingly.
Also, add a kselftest that can reproduce the lockup and verifies TC mirred
ability to account for further packet drops after TC mirred egress->ingress
(when the nest level is 1).
[1] https://lore.kernel.org/netdev/33dc43f587ec1388ba456b4915c75f02a8aae226.1663945716.git.dcaratti@redhat.com/
[2] https://lore.kernel.org/netdev/Y0w%2FWWY60gqrtGLp@pop-os.localdomain/
[3] such behavior is not guaranteed: for example, if RPS or skb RX
timestamping is enabled on the mirred target device, the kernel
can defer receiving the skb and return NET_RX_SUCCESS inside
tcf_mirred_forward().
Reported-by: William Zhao <wizhao@redhat.com>
CC: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/act_mirred.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index c8abb5136491..8037ec9b1d31 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -206,12 +206,19 @@ release_idr: return err; } +static bool is_mirred_nested(void) +{ + return unlikely(__this_cpu_read(mirred_nest_level) > 1); +} + static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb) { int err; if (!want_ingress) err = tcf_dev_queue_xmit(skb, dev_queue_xmit); + else if (is_mirred_nested()) + err = netif_rx(skb); else err = netif_receive_skb(skb); |