Commit eb1f0023 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

lockdep,trace: Expose tracepoints 



The lockdep tracepoints are under the lockdep recursion counter, this
has a bunch of nasty side effects:

 - TRACE_IRQFLAGS doesn't work across the entire tracepoint

 - RCU-lockdep doesn't see the tracepoints either, hiding numerous
   "suspicious RCU usage" warnings.

Pull the trace_lock_*() tracepoints completely out from under the
lockdep recursion handling and completely rely on the trace level
recusion handling -- also, tracing *SHOULD* not be taking locks in any
case.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: default avatarMarco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200821085348.782688941@infradead.org
parent 044d0d6d

kernel/locking/lockdep.c

+9 −5
Original line number Diff line number Diff line
@@ -4977,6 +4977,8 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
{

	unsigned long flags;



	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);



	if (unlikely(current->lockdep_recursion)) {

		/* XXX allow trylock from NMI ?!? */

		if (lockdep_nmi() && !trylock) {
@@ -5001,7 +5003,6 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
	check_flags(flags);



	current->lockdep_recursion++;

	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);

	__lock_acquire(lock, subclass, trylock, read, check,

		       irqs_disabled_flags(flags), nest_lock, ip, 0, 0);

	lockdep_recursion_finish();
@@ -5013,13 +5014,15 @@ void lock_release(struct lockdep_map *lock, unsigned long ip) 
{

	unsigned long flags;



	trace_lock_release(lock, ip);



	if (unlikely(current->lockdep_recursion))

		return;



	raw_local_irq_save(flags);

	check_flags(flags);



	current->lockdep_recursion++;

	trace_lock_release(lock, ip);

	if (__lock_release(lock, ip))

		check_chain_key(current);

	lockdep_recursion_finish();
@@ -5205,8 +5208,6 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip) 
		hlock->holdtime_stamp = now;

	}



	trace_lock_acquired(lock, ip);



	stats = get_lock_stats(hlock_class(hlock));

	if (waittime) {

		if (hlock->read)
@@ -5225,6 +5226,8 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) 
{

	unsigned long flags;



	trace_lock_acquired(lock, ip);



	if (unlikely(!lock_stat || !debug_locks))

		return;
@@ -5234,7 +5237,6 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) 
	raw_local_irq_save(flags);

	check_flags(flags);

	current->lockdep_recursion++;

	trace_lock_contended(lock, ip);

	__lock_contended(lock, ip);

	lockdep_recursion_finish();

	raw_local_irq_restore(flags);
@@ -5245,6 +5247,8 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip) 
{

	unsigned long flags;



	trace_lock_contended(lock, ip);



	if (unlikely(!lock_stat || !debug_locks))

		return;

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