[PATCH net-next v4 10/15] net/sched: act_mirred: Move the recursion counter struct netdev_xmit
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2025-05-12 09:27:48
Also in:
linux-rt-devel
Subsystem:
networking drivers, networking [general], tc subsystem, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
mirred_nest_level is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Move mirred_nest_level to struct netdev_xmit as u8, provide wrappers. Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Cong Wang <redacted> Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- include/linux/netdevice_xmit.h | 3 +++ net/sched/act_mirred.c | 28 +++++++++++++++++++++++++--- 2 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/include/linux/netdevice_xmit.h b/include/linux/netdevice_xmit.h
index 38325e0702968..848735b3a7c02 100644
--- a/include/linux/netdevice_xmit.h
+++ b/include/linux/netdevice_xmit.h@@ -8,6 +8,9 @@ struct netdev_xmit { #ifdef CONFIG_NET_EGRESS u8 skip_txqueue; #endif +#if IS_ENABLED(CONFIG_NET_ACT_MIRRED) + u8 sched_mirred_nest; +#endif }; #endif
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 5b38143659249..5f01f567c934d 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c@@ -30,7 +30,29 @@ static LIST_HEAD(mirred_list); static DEFINE_SPINLOCK(mirred_list_lock); #define MIRRED_NEST_LIMIT 4 -static DEFINE_PER_CPU(unsigned int, mirred_nest_level); + +#ifndef CONFIG_PREEMPT_RT +static u8 tcf_mirred_nest_level_inc_return(void) +{ + return __this_cpu_inc_return(softnet_data.xmit.sched_mirred_nest); +} + +static void tcf_mirred_nest_level_dec(void) +{ + __this_cpu_dec(softnet_data.xmit.sched_mirred_nest); +} + +#else +static u8 tcf_mirred_nest_level_inc_return(void) +{ + return current->net_xmit.sched_mirred_nest++; +} + +static void tcf_mirred_nest_level_dec(void) +{ + current->net_xmit.sched_mirred_nest--; +} +#endif static bool tcf_mirred_is_act_redirect(int action) {
@@ -423,7 +445,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, int m_eaction; u32 blockid; - nest_level = __this_cpu_inc_return(mirred_nest_level); + nest_level = tcf_mirred_nest_level_inc_return(); if (unlikely(nest_level > MIRRED_NEST_LIMIT)) { net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n", netdev_name(skb->dev));
@@ -454,7 +476,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, retval); dec_nest_level: - __this_cpu_dec(mirred_nest_level); + tcf_mirred_nest_level_dec(); return retval; }
--
2.49.0