From: Justin Iurman <justin.iurman@uliege.be>
To: netdev@vger.kernel.org
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, horms@kernel.org, kuniyu@amazon.com,
justin.iurman@uliege.be,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Eduard Zingerman <eddyz87@gmail.com>, bpf <bpf@vger.kernel.org>,
Stanislav Fomichev <stfomichev@gmail.com>,
Sebastian Sewior <bigeasy@linutronix.de>,
Andrea Mayer <andrea.mayer@uniroma2.it>,
Stefano Salsano <stefano.salsano@uniroma2.it>,
Paolo Lungaroni <paolo.lungaroni@uniroma2.it>
Subject: [PATCH net v3] net: lwtunnel: disable BHs when required
Date: Wed, 16 Apr 2025 18:07:16 +0200 [thread overview]
Message-ID: <20250416160716.8823-1-justin.iurman@uliege.be> (raw)
v3:
- removed unrelated code cleanups
v2:
- https://lore.kernel.org/netdev/20250415173239.39781-1-justin.iurman@uliege.be/
v1:
- https://lore.kernel.org/netdev/20250403083956.13946-1-justin.iurman@uliege.be/
In lwtunnel_{output|xmit}(), dev_xmit_recursion() may be called in
preemptible scope for PREEMPT kernels. This patch disables BHs before
calling dev_xmit_recursion(). BHs are re-enabled only at the end, since
we must ensure the same CPU is used for both dev_xmit_recursion_inc()
and dev_xmit_recursion_dec() (and any other recursion levels in some
cases) in order to maintain valid per-cpu counters.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Closes: https://lore.kernel.org/netdev/CAADnVQJFWn3dBFJtY+ci6oN1pDFL=TzCmNbRgey7MdYxt_AP2g@mail.gmail.com/
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Closes: https://lore.kernel.org/netdev/m2h62qwf34.fsf@gmail.com/
Fixes: 986ffb3a57c5 ("net: lwtunnel: fix recursion loops")
Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
---
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Stanislav Fomichev <stfomichev@gmail.com>
Cc: Sebastian Sewior <bigeasy@linutronix.de>
Cc: Andrea Mayer <andrea.mayer@uniroma2.it>
Cc: Stefano Salsano <stefano.salsano@uniroma2.it>
Cc: Paolo Lungaroni <paolo.lungaroni@uniroma2.it>
---
net/core/lwtunnel.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index e39a459540ec..60f27cb4e54f 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -333,6 +333,8 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
struct dst_entry *dst;
int ret;
+ local_bh_disable();
+
if (dev_xmit_recursion()) {
net_crit_ratelimited("%s(): recursion limit reached on datapath\n",
__func__);
@@ -348,8 +350,10 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
- lwtstate->type > LWTUNNEL_ENCAP_MAX)
- return 0;
+ lwtstate->type > LWTUNNEL_ENCAP_MAX) {
+ ret = 0;
+ goto out;
+ }
ret = -EOPNOTSUPP;
rcu_read_lock();
@@ -364,11 +368,13 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
if (ret == -EOPNOTSUPP)
goto drop;
- return ret;
+ goto out;
drop:
kfree_skb(skb);
+out:
+ local_bh_enable();
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_output);
@@ -380,6 +386,8 @@ int lwtunnel_xmit(struct sk_buff *skb)
struct dst_entry *dst;
int ret;
+ local_bh_disable();
+
if (dev_xmit_recursion()) {
net_crit_ratelimited("%s(): recursion limit reached on datapath\n",
__func__);
@@ -396,8 +404,10 @@ int lwtunnel_xmit(struct sk_buff *skb)
lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
- lwtstate->type > LWTUNNEL_ENCAP_MAX)
- return 0;
+ lwtstate->type > LWTUNNEL_ENCAP_MAX) {
+ ret = 0;
+ goto out;
+ }
ret = -EOPNOTSUPP;
rcu_read_lock();
@@ -412,11 +422,13 @@ int lwtunnel_xmit(struct sk_buff *skb)
if (ret == -EOPNOTSUPP)
goto drop;
- return ret;
+ goto out;
drop:
kfree_skb(skb);
+out:
+ local_bh_enable();
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_xmit);
@@ -428,6 +440,8 @@ int lwtunnel_input(struct sk_buff *skb)
struct dst_entry *dst;
int ret;
+ DEBUG_NET_WARN_ON_ONCE(!in_softirq());
+
if (dev_xmit_recursion()) {
net_crit_ratelimited("%s(): recursion limit reached on datapath\n",
__func__);
--
2.34.1
next reply other threads:[~2025-04-16 16:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-16 16:07 Justin Iurman [this message]
2025-04-21 13:44 ` [PATCH net v3] net: lwtunnel: disable BHs when required Simon Horman
2025-04-22 23:59 ` Jakub Kicinski
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