trace_call__##name() was added by commit 677a3d82b640 ("tracepoint: Add
trace_call__##name() API") for callers that already gate on
trace_##name##_enabled(), letting them skip the redundant
static_branch_unlikely() re-evaluation. The LOCKDEP rcu_is_watching()
WARN_ONCE() that trace_##name() carries on the disabled path was not
mirrored, so the cold-path coverage added by commit c2679254b9c9
("tracing: Make tracepoint lockdep check actually test something") is
lost for trace_call__##name() callers when the tracepoint is disabled.
When the tracepoint is enabled, the rcu_dereference inside
__DO_TRACE_CALL() already trips under PROVE_RCU, so the warning is
only needed on the !enabled path. The natural place is the gate that
trace_call__##name() callers consult: trace_##name##_enabled().
Fixes: 677a3d82b640 ("tracepoint: Add trace_call__##name() API")
Cc: Vineeth Pillai (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: David Carlier <[email protected]>
---
include/linux/tracepoint.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 578e520b6ee6..3b3ab19c2627 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -293,6 +293,10 @@ static inline struct tracepoint
*tracepoint_ptr_deref(tracepoint_ptr_t *p)
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);\
}
--
2.53.0
