diff mbox series

[net-next,v2,13/18] net/sched: act_mirred: Move the recursion counter struct netdev_xmit

Message ID 20250414160754.503321-14-bigeasy@linutronix.de (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series net: Cover more per-CPU storage with local nested BH locking. | expand

Checks

Context Check Description
netdev/series_format fail Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 465 this patch: 465
netdev/build_tools success Errors and warnings before: 26 (+2) this patch: 26 (+2)
netdev/cc_maintainers warning 3 maintainers not CCed: andrew+netdev@lunn.ch rostedt@goodmis.org clrkwllms@kernel.org
netdev/build_clang success Errors and warnings before: 903 this patch: 903
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 15959 this patch: 15959
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 55 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-04-15--18-01 (tests: 900)

Commit Message

Sebastian Andrzej Siewior April 14, 2025, 4:07 p.m. UTC 
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 <xiyou.wangcong@gmail.com>
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 mbox series

Patch

diff --git a/include/linux/netdevice_xmit.h b/include/linux/netdevice_xmit.h
index 3bbbc1a9860a3..4793ec42b1faa 100644
--- a/include/linux/netdevice_xmit.h
+++ b/include/linux/netdevice_xmit.h
@@ -11,6 +11,9 @@  struct netdev_xmit {
 #if IS_ENABLED(CONFIG_NF_DUP_NETDEV)
 	u8 nf_dup_skb_recursion;
 #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;
 }