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: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200821085348.782688941@infradead.org

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c872e95e6e4d14b07432006abbfbc326d28883a0..54b74fabf40c7bd88633b717423403add6911d8c 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -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;