Add trace_invoke_##name() as a companion to trace_##name(). When a caller already guards a tracepoint with an explicit enabled check:
if (trace_foo_enabled() && cond) trace_foo(args);
trace_foo() internally repeats the static_branch_unlikely() test, which the compiler cannot fold since static branches are patched binary instructions. This results in two static-branch evaluations for every guarded call site.
trace_invoke_##name() calls __do_trace_##name() directly, skipping the redundant static-branch re-check. This avoids leaking the internal __do_trace_##name() symbol into call sites while still eliminating the double evaluation:
if (trace_foo_enabled() && cond) trace_invoke_foo(args); /* calls __do_trace_foo() directly */
Three locations are updated: - __DECLARE_TRACE: invoke form omits static_branch_unlikely, retains the LOCKDEP RCU-watching assertion. - __DECLARE_TRACE_SYSCALL: same, plus retains might_fault(). - !TRACEPOINTS_ENABLED stub: empty no-op so callers compile cleanly when tracepoints are compiled out.
Suggested-by: Steven Rostedt rostedt@goodmis.org Suggested-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Vineeth Pillai (Google) vineeth@bitbyteword.org Assisted-by: Claude:claude-sonnet-4-6 --- include/linux/tracepoint.h | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 22ca1c8b54f32..07219316a8e14 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -294,6 +294,10 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ } \ + } \ + static inline void trace_invoke_##name(proto) \ + { \ + __do_trace_##name(args); \ }
#define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \ @@ -313,6 +317,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ } \ + } \ + static inline void trace_invoke_##name(proto) \ + { \ + might_fault(); \ + __do_trace_##name(args); \ }
/* @@ -398,6 +407,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \ static inline void trace_##name(proto) \ { } \ + static inline void trace_invoke_##name(proto) \ + { } \ static inline int \ register_trace_##name(void (*probe)(data_proto), \ void *data) \