Commit 40db1739 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Peter Zijlstra
Browse files

lockdep: Add hrtimer context tracing bits 



Set current->irq_config = 1 for hrtimers which are not marked to expire in
hard interrupt context during hrtimer_init(). These timers will expire in
softirq context on PREEMPT_RT.

Setting this allows lockdep to differentiate these timers. If a timer is
marked to expire in hard interrupt context then the timer callback is not
supposed to acquire a regular spinlock instead of a raw_spinlock in the
expiry callback.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.534508206@linutronix.de
parent de8f5e4f

include/linux/irqflags.h

+15 −0
Original line number Diff line number Diff line
@@ -56,6 +56,19 @@ do { \ 
do {						\

	current->softirq_context--;		\

} while (0)



# define lockdep_hrtimer_enter(__hrtimer)		\

	  do {						\

		  if (!__hrtimer->is_hard)		\

			current->irq_config = 1;	\

	  } while (0)



# define lockdep_hrtimer_exit(__hrtimer)		\

	  do {						\

		  if (!__hrtimer->is_hard)		\

			current->irq_config = 0;	\

	  } while (0)



#else

# define trace_hardirqs_on()		do { } while (0)

# define trace_hardirqs_off()		do { } while (0)
@@ -68,6 +81,8 @@ do { \ 
# define trace_hardirq_exit()		do { } while (0)

# define lockdep_softirq_enter()	do { } while (0)

# define lockdep_softirq_exit()		do { } while (0)

# define lockdep_hrtimer_enter(__hrtimer)		do { } while (0)

# define lockdep_hrtimer_exit(__hrtimer)		do { } while (0)

#endif



#if defined(CONFIG_IRQSOFF_TRACER) || \

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -983,6 +983,7 @@ struct task_struct { 
	unsigned int			softirq_enable_event;

	int				softirqs_enabled;

	int				softirq_context;

	int				irq_config;

#endif



#ifdef CONFIG_LOCKDEP

kernel/locking/lockdep.c

+1 −1
Original line number Diff line number Diff line
@@ -4025,7 +4025,7 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next) 
		/*

		 * Check if force_irqthreads will run us threaded.

		 */

		if (curr->hardirq_threaded)

		if (curr->hardirq_threaded || curr->irq_config)

			curr_inner = LD_WAIT_CONFIG;

		else

			curr_inner = LD_WAIT_SPIN;

kernel/time/hrtimer.c

+5 −1
Original line number Diff line number Diff line
@@ -1404,7 +1404,7 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id, 
	base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;

	base += hrtimer_clockid_to_base(clock_id);

	timer->is_soft = softtimer;

	timer->is_hard = !softtimer;

	timer->is_hard = !!(mode & HRTIMER_MODE_HARD);

	timer->base = &cpu_base->clock_base[base];

	timerqueue_init(&timer->node);

}
@@ -1514,7 +1514,11 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base, 
	 */

	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);

	trace_hrtimer_expire_entry(timer, now);

	lockdep_hrtimer_enter(timer);



	restart = fn(timer);



	lockdep_hrtimer_exit(timer);

	trace_hrtimer_expire_exit(timer);

	raw_spin_lock_irq(&cpu_base->lock);

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