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tracepoints: Use WARN() and not WARN_ON() for warnings

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There are two WARN_ON*() warnings in tracepoint.h that deal with RCU
usage. But when they trigger, especially from using a TRACE_EVENT()
macro, the information is not very helpful and is confusing:

 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 0 at include/trace/events/lock.h:24 lock_acquire+0x2b2/0x2d0

Where the above warning takes you to:

 TRACE_EVENT(lock_acquire,  <<<--- line 24 in lock.h

	TP_PROTO(struct lockdep_map *lock, unsigned int subclass,
		int trylock, int read, int check,
		struct lockdep_map *next_lock, unsigned long ip),
	[..]

Change the WARN_ON_ONCE() to WARN_ONCE() and add a string that allows
someone to search for exactly where the bug happened.

Link: https://lore.kernel.org/linux-trace-kernel/20240228133112.0d64fb1b@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Borislav Petkov <bp@alien8.de>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2024-02-28 13:31:12 -05:00
parent d6cb38e108
commit 1b27312410
1 changed files with 4 additions and 2 deletions
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6
include/linux/tracepoint.h
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@ -199,7 +199,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
if (!(cond)) \
return; \
\
if (WARN_ON_ONCE(RCUIDLE_COND(rcuidle))) \
if (WARN_ONCE(RCUIDLE_COND(rcuidle), \
"Bad RCU usage for tracepoint")) \
return; \
\
/* keep srcu and sched-rcu usage consistent */ \
@ -259,7 +260,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
TP_ARGS(args), \
TP_CONDITION(cond), 0); \
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
WARN_ON_ONCE(!rcu_is_watching()); \
WARN_ONCE(!rcu_is_watching(), \
"RCU not watching for tracepoint"); \
} \
} \
__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \