From: Steven Rostedt Date: Wed, 1 Jul 2026 17:27:44 +0000 (-0400) Subject: tracing: Add a no-rcu-check version of trace_##event##_enabled() X-Git-Tag: v7.2-rc3~9^2~6 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1e67bb60bb03518d3bdd59a48c65d69e6d773bb8;p=thirdparty%2Fkernel%2Flinux.git tracing: Add a no-rcu-check version of trace_##event##_enabled() Tracepoints require that RCU is watching. To prevent them from being used in places that RCU is not watching, the trace_##event() macro always calls rcu_is_watching() even when the event is not enabled and warns if RCU is not watching. This is to make sure a warning is triggered even if the tracepoint is never enabled (as it is only a bug when it is). It was noticed that tracepoints could be hidden within trace_#event#_enabled() calls, which are used to do extra work for the tracepoint only if the tracepoint is enabled. But this also can hide the fact that a tracepoint is placed in a location that can be called when RCU is not watching. Commit 9764e731ef6ab ("tracepoint: Add lockdep rcu_is_watching() check to trace_##name##_enabled()") added a check to the trace_##event##_enabled() macro to make sure RCU is watching when it is called to make sure not to hide the bug of a tracepoint being called when RCU is not watching. There is one case in the irq_disable tracepoint where it is within a trace_irq_disable_enabled() block, but it checks if RCU is watching, and if it isn't, it makes a call to ct_irq_enter() that makes RCU watch again. But because trace_irq_disable_enabled() now checks if RCU is watching and will trigger if it isn't. This is a false warning as the code within the block handles this case. Add a new internal macro __trace_##event##_enabled() that doesn't check if RCU is watching, and convert the irq_enable/disable tracepoints over to it. Link: https://patch.msgid.link/20260701132744.6a7fc68b@robin Reported-by: Geert Uytterhoeven Closes: https://lore.kernel.org/all/CAMuHMdXud_RpWag_hFqa2ByBGRxg6KnxGL1ObCWZrpTsk3TfAw@mail.gmail.com/ Fixes: 9764e731ef6ab ("tracepoint: Add lockdep rcu_is_watching() check to trace_##name##_enabled()") Tested-by: Geert Uytterhoeven Signed-off-by: Steven Rostedt --- diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 4a0c36f40fe2..e0d838c9ce93 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -292,13 +292,18 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) { \ } \ static inline bool \ + __trace_##name##_enabled(void) \ + { \ + return static_branch_unlikely(&__tracepoint_##name.key);\ + } \ + static inline bool \ trace_##name##_enabled(void) \ { \ if (IS_ENABLED(CONFIG_LOCKDEP)) { \ WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ } \ - return static_branch_unlikely(&__tracepoint_##name.key);\ + return __trace_##name##_enabled(); \ } #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \ @@ -457,6 +462,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) { \ } \ static inline bool \ + __trace_##name##_enabled(void) \ + { \ + return false; \ + } \ + static inline bool \ trace_##name##_enabled(void) \ { \ return false; \ diff --git a/kernel/trace/trace_preemptirq.c b/kernel/trace/trace_preemptirq.c index 0c42b15c3800..b63e3558948f 100644 --- a/kernel/trace/trace_preemptirq.c +++ b/kernel/trace/trace_preemptirq.c @@ -30,7 +30,7 @@ #else #define trace(point, args) \ do { \ - if (trace_##point##_enabled()) { \ + if (__trace_##point##_enabled()) { \ bool exit_rcu = false; \ if (in_nmi()) \ break; \