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From: Peter Zijlstra <peterz@infradead.org>
To: linux-kernel@vger.kernel.org, mingo@kernel.org, will@kernel.org
Cc: npiggin@gmail.com, elver@google.com, jgross@suse.com,
	paulmck@kernel.org, rostedt@goodmis.org, rjw@rjwysocki.net,
	joel@joelfernandes.org, svens@linux.ibm.com, tglx@linutronix.de,
	peterz@infradead.org
Subject: [PATCH 9/9] lockdep,trace: Expose tracepoints
Date: Thu, 20 Aug 2020 09:30:40 +0200	[thread overview]
Message-ID: <20200820074640.810404638@infradead.org> (raw)
In-Reply-To: 20200820073031.886217423@infradead.org

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: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/locking/lockdep.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5044,6 +5044,8 @@ void lock_acquire(struct lockdep_map *lo
 {
 	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) {
@@ -5068,7 +5070,6 @@ void lock_acquire(struct lockdep_map *lo
 	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();
@@ -5080,13 +5081,15 @@ void lock_release(struct lockdep_map *lo
 {
 	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();
@@ -5272,8 +5275,6 @@ __lock_acquired(struct lockdep_map *lock
 		hlock->holdtime_stamp = now;
 	}
 
-	trace_lock_acquired(lock, ip);
-
 	stats = get_lock_stats(hlock_class(hlock));
 	if (waittime) {
 		if (hlock->read)
@@ -5292,6 +5293,8 @@ void lock_contended(struct lockdep_map *
 {
 	unsigned long flags;
 
+	trace_lock_contended(lock, ip);
+
 	if (unlikely(!lock_stat || !debug_locks))
 		return;
 
@@ -5301,7 +5304,6 @@ void lock_contended(struct lockdep_map *
 	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);
@@ -5312,6 +5314,8 @@ void lock_acquired(struct lockdep_map *l
 {
 	unsigned long flags;
 
+	trace_lock_acquired(lock, ip);
+
 	if (unlikely(!lock_stat || !debug_locks))
 		return;
 



  parent reply	other threads:[~2020-08-20  7:50 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20  7:30 [PATCH 0/9] TRACE_IRQFLAGS wreckage Peter Zijlstra
2020-08-20  7:30 ` [PATCH 1/9] lockdep: Use raw_cpu_*() for per-cpu variables Peter Zijlstra
2020-08-20 13:54   ` Steven Rostedt
2020-08-20  7:30 ` [PATCH 2/9] sched,idle,rcu: Push rcu_idle deeper into the idle path Peter Zijlstra
2020-08-20 13:58   ` Steven Rostedt
2020-08-20  7:30 ` [PATCH 3/9] cpuidle: Make CPUIDLE_FLAG_TLB_FLUSHED generic Peter Zijlstra
2020-08-20  7:30 ` [PATCH 4/9] cpuidle: Move trace_cpu_idle() into generic code Peter Zijlstra
2020-08-20  7:30 ` [PATCH 5/9] x86/entry: Remove unused THUNKs Peter Zijlstra
2020-08-20  7:30 ` [PATCH 6/9] locking/lockdep: Cleanup Peter Zijlstra
2020-08-20  7:30 ` [PATCH 7/9] nds32: Implement arch_irqs_disabled() Peter Zijlstra
2020-08-20  7:30 ` [PATCH 8/9] lockdep: Only trace IRQ edges Peter Zijlstra
2020-08-20  7:30 ` Peter Zijlstra [this message]
2020-08-20 14:36 ` [PATCH 0/9] TRACE_IRQFLAGS wreckage Steven Rostedt
2020-08-20 14:39   ` Steven Rostedt
2020-08-20 14:49   ` Marco Elver
2020-08-20 14:58   ` peterz
2020-08-20 16:53     ` Steven Rostedt
2020-08-20 17:20     ` Marco Elver
2020-08-20 19:59       ` Steven Rostedt
2020-08-21  6:37         ` Marco Elver
2020-08-21  6:54       ` peterz
2020-08-21  7:05         ` Marco Elver
2020-08-27  7:54       ` [tip: sched/urgent] sched: Use __always_inline on is_idle_task() tip-bot2 for Marco Elver

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