Commit 49915ac3 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Peter Zijlstra
Browse files

lockdep: Annotate irq_work 



Mark irq_work items with IRQ_WORK_HARD_IRQ which should be invoked in
hardirq context even on PREEMPT_RT. IRQ_WORK without this flag will be
invoked in softirq context on PREEMPT_RT.

Set ->irq_config to 1 for the IRQ_WORK items which are invoked in softirq
context so lockdep knows that these can safely acquire a spinlock_t.

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/20200321113242.643576700@linutronix.de
parent 40db1739

include/linux/irq_work.h

+2 −0
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 


/* Doesn't want IPI, wait for tick: */

#define IRQ_WORK_LAZY		BIT(2)

/* Run hard IRQ context, even on RT */

#define IRQ_WORK_HARD_IRQ	BIT(3)



#define IRQ_WORK_CLAIMED	(IRQ_WORK_PENDING | IRQ_WORK_BUSY)

include/linux/irqflags.h

+13 −0
Original line number Diff line number Diff line
@@ -69,6 +69,17 @@ do { \ 
			current->irq_config = 0;	\

	  } while (0)



# define lockdep_irq_work_enter(__work)					\

	  do {								\

		  if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\

			current->irq_config = 1;			\

	  } while (0)

# define lockdep_irq_work_exit(__work)					\

	  do {								\

		  if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\

			current->irq_config = 0;			\

	  } while (0)



#else

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

# define trace_hardirqs_off()		do { } while (0)
@@ -83,6 +94,8 @@ do { \ 
# define lockdep_softirq_exit()		do { } while (0)

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

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

# define lockdep_irq_work_enter(__work)		do { } while (0)

# define lockdep_irq_work_exit(__work)		do { } while (0)

#endif



#if defined(CONFIG_IRQSOFF_TRACER) || \

kernel/irq_work.c

+2 −0
Original line number Diff line number Diff line
@@ -153,7 +153,9 @@ static void irq_work_run_list(struct llist_head *list) 
		 */

		flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);



		lockdep_irq_work_enter(work);

		work->func(work);

		lockdep_irq_work_exit(work);

		/*

		 * Clear the BUSY bit and return to the free state if

		 * no-one else claimed it meanwhile.

kernel/rcu/tree.c

+1 −0
Original line number Diff line number Diff line
@@ -1113,6 +1113,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) 
		    !rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq &&

		    (rnp->ffmask & rdp->grpmask)) {

			init_irq_work(&rdp->rcu_iw, rcu_iw_handler);

			atomic_set(&rdp->rcu_iw.flags, IRQ_WORK_HARD_IRQ);

			rdp->rcu_iw_pending = true;

			rdp->rcu_iw_gp_seq = rnp->gp_seq;

			irq_work_queue_on(&rdp->rcu_iw, rdp->cpu);

kernel/time/tick-sched.c

+1 −0
Original line number Diff line number Diff line
@@ -245,6 +245,7 @@ static void nohz_full_kick_func(struct irq_work *work) 


static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {

	.func = nohz_full_kick_func,

	.flags = ATOMIC_INIT(IRQ_WORK_HARD_IRQ),

};



/*

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