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alistair23-linux
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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
zero-sugar-mainline-defconfig
Peter Zijlstra 2020-08-07 20:53:16 +02:00
parent 044d0d6de9
commit eb1f00237a
1 changed files with 9 additions and 5 deletions
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14
kernel/locking/lockdep.c
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@ -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;