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| author | Yun Zhou <yun.zhou@windriver.com> | 2026-07-13 23:09:45 +0800 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-07-23 13:01:57 +0200 |
| commit | 675ed582c1aa4d919dd535490de08c015005c653 (patch) | |
| tree | fd2a88368afac714abf7e3ed6c192c4f6736d858 /net | |
| parent | ba0533fc163f905fe817cfabdf8ed4058da44800 (diff) | |
| download | linux-next-675ed582c1aa4d919dd535490de08c015005c653.tar.gz linux-next-675ed582c1aa4d919dd535490de08c015005c653.zip | |
net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM
Before commit 00d066a4d4ed ("netdev_features: convert NETIF_F_LLTX to
dev->lltx"), NETIF_F_LLTX was set unconditionally in both
__gre_tunnel_init() and ip6gre_tnl_init_features() alongside
GRE_FEATURES:
dev->features |= GRE_FEATURES | NETIF_F_LLTX;
When that commit converted NETIF_F_LLTX to the dev->lltx flag, it
placed 'dev->lltx = true' after the SEQ/CSUM early returns instead
of before them. This causes GRE/GRETAP/ip6gre tunnels with SEQ or
CSUM+encap to lose lockless TX, reintroducing _xmit_lock acquisition
around their ndo_start_xmit. Since GRE xmit re-enters the stack via
ip_tunnel_xmit(), holding _xmit_lock risks ABBA deadlock with the
underlay device.
CPU0 CPU1
---- ----
lock(&qdisc_xmit_lock_key#6);
lock(&qdisc_xmit_lock_key#3);
lock(&qdisc_xmit_lock_key#6);
lock(&qdisc_xmit_lock_key#3);
Fix by moving dev->lltx = true before the early returns in both
functions, restoring the original unconditional behavior.
Fixes: 00d066a4d4ed ("netdev_features: convert NETIF_F_LLTX to dev->lltx")
Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260713150945.1779628-1-yun.zhou@windriver.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/ip_gre.c | 4 | ||||
| -rw-r--r-- | net/ipv6/ip6_gre.c | 4 |
2 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 3efdfb4ffa21..0ba1e94e9012 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1018,6 +1018,8 @@ static void __gre_tunnel_init(struct net_device *dev) dev->features |= GRE_FEATURES; dev->hw_features |= GRE_FEATURES; + dev->lltx = true; + /* TCP offload with GRE SEQ is not supported, nor can we support 2 * levels of outer headers requiring an update. */ @@ -1029,8 +1031,6 @@ static void __gre_tunnel_init(struct net_device *dev) dev->features |= NETIF_F_GSO_SOFTWARE; dev->hw_features |= NETIF_F_GSO_SOFTWARE; - - dev->lltx = true; } static int ipgre_tunnel_init(struct net_device *dev) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 7c09a269b352..b843116e9b70 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1455,6 +1455,8 @@ static void ip6gre_tnl_init_features(struct net_device *dev) dev->features |= GRE6_FEATURES; dev->hw_features |= GRE6_FEATURES; + dev->lltx = true; + /* TCP offload with GRE SEQ is not supported, nor can we support 2 * levels of outer headers requiring an update. */ @@ -1466,8 +1468,6 @@ static void ip6gre_tnl_init_features(struct net_device *dev) dev->features |= NETIF_F_GSO_SOFTWARE; dev->hw_features |= NETIF_F_GSO_SOFTWARE; - - dev->lltx = true; } static int ip6gre_tunnel_init_common(struct net_device *dev) |