On 06.05.24 03:54, Wen Gu wrote:
A netdev refcnt leak issue was found when unregistering netdev after
using SMC. It can be reproduced as follows.
- run tests based on SMC.
- unregister the net device.
The following error message can be observed.
'unregister_netdevice: waiting for ethx to become free. Usage count = x'
With CONFIG_NET_DEV_REFCNT_TRACKER set, more detailed error message can
be provided by refcount tracker:
unregister_netdevice: waiting for eth1 to become free. Usage count = 2
ref_tracker: eth%d@ffff9cabc3bf8548 has 1/1 users at
___neigh_create+0x8e/0x420
neigh_event_ns+0x52/0xc0
arp_process+0x7c0/0x860
__netif_receive_skb_list_core+0x258/0x2c0
__netif_receive_skb_list+0xea/0x150
netif_receive_skb_list_internal+0xf2/0x1b0
napi_complete_done+0x73/0x1b0
mlx5e_napi_poll+0x161/0x5e0 [mlx5_core]
__napi_poll+0x2c/0x1c0
net_rx_action+0x2a7/0x380
__do_softirq+0xcd/0x2a7
It is because in smc_ib_find_route(), neigh_lookup() takes a netdev
refcnt but does not release. So fix it.
Fixes: e5c4744cfb59 ("net/smc: add SMC-Rv2 connection establishment")
Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
---
net/smc/smc_ib.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c
index 97704a9e84c7..b431bd8a5172 100644
--- a/net/smc/smc_ib.c
+++ b/net/smc/smc_ib.c
@@ -210,10 +210,11 @@ int smc_ib_find_route(struct net *net, __be32 saddr, __be32 daddr,
goto out;
if (rt->rt_uses_gateway && rt->rt_gw_family != AF_INET)
goto out;
- neigh = rt->dst.ops->neigh_lookup(&rt->dst, NULL, &fl4.daddr);
+ neigh = dst_neigh_lookup(&rt->dst, &fl4.daddr);
if (neigh) {
memcpy(nexthop_mac, neigh->ha, ETH_ALEN);
*uses_gateway = rt->rt_uses_gateway;
+ neigh_release(neigh);
return 0;
}
out:
Hi Wen,
Thanks for fixing that! It looks good to me and works well.
Please release rt for that condition in the next version. (Thx, @Ratheesh!)
Thanks,
Wenjia
