[PATCH] completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()

Sebastian Siewior
2020-03-23T15:20:19Z

The warning was intended to spot complete_all() users from hardirq
context on PREEMPT_RT. The warning as-is will also trigger in interrupt
handlers, which are threaded on PREEMPT_RT, which was not intended.

Use lockdep_assert_RT_in_threaded_ctx() which triggers in non-preemptive
context on PREEMPT_RT.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/lockdep.h | 15 +++++++++++++++
kernel/sched/completion.c | 2 +-
2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 425b4ceb7cd07..206774ac69460 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -711,6 +711,21 @@ do { \
# define lockdep_assert_in_irq() do { } while (0)
#endif

+#ifdef CONFIG_PROVE_RAW_LOCK_NESTING
+
+# define lockdep_assert_RT_in_threaded_ctx() do { \
+ WARN_ONCE(debug_locks && !current->lockdep_recursion && \
+ current->hardirq_context && \
+ !(current->hardirq_threaded || current->irq_config), \
+ "Not in threaded context on PREEMPT_RT as expected\n"); \
+} while (0)
+
+#else
+
+# define lockdep_assert_RT_in_threaded_ctx() do { } while (0)
+
+#endif
+
#ifdef CONFIG_LOCKDEP
void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
#else
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
index f15e96164ff1e..a778554f9dad7 100644
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -58,7 +58,7 @@ void complete_all(struct completion *x)
{
unsigned long flags;

- WARN_ON(irqs_disabled());
+ lockdep_assert_RT_in_threaded_ctx();

raw_spin_lock_irqsave(&x->wait.lock, flags);
x->done = UINT_MAX;
--
2.26.0.rc2