Commit a649d25d authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Add lockdep_assert_irqs_disabled() to rcu_sched_clock_irq() and callees 

This commit adds a number of lockdep_assert_irqs_disabled() calls
to rcu_sched_clock_irq() and a number of the functions that it calls.
The point of this is to help track down a situation where lockdep appears
to be insisting that interrupts are enabled within these functions, which
should only ever be invoked from the scheduling-clock interrupt handler.

Link: https://lore.kernel.org/lkml/20201111133813.GA81547@elver.google.com/


Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent c5586e32

kernel/rcu/tree.c

+4 −0
Original line number Diff line number Diff line
@@ -2553,6 +2553,7 @@ static void rcu_do_batch(struct rcu_data *rdp) 
void rcu_sched_clock_irq(int user)

{

	trace_rcu_utilization(TPS("Start scheduler-tick"));

	lockdep_assert_irqs_disabled();

	raw_cpu_inc(rcu_data.ticks_this_gp);

	/* The load-acquire pairs with the store-release setting to true. */

	if (smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) {
@@ -2566,6 +2567,7 @@ void rcu_sched_clock_irq(int user) 
	rcu_flavor_sched_clock_irq(user);

	if (rcu_pending(user))

		invoke_rcu_core();

	lockdep_assert_irqs_disabled();



	trace_rcu_utilization(TPS("End scheduler-tick"));

}
@@ -3690,6 +3692,8 @@ static int rcu_pending(int user) 
	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);

	struct rcu_node *rnp = rdp->mynode;



	lockdep_assert_irqs_disabled();



	/* Check for CPU stalls, if enabled. */

	check_cpu_stall(rdp);

kernel/rcu/tree_plugin.h

+1 −0
Original line number Diff line number Diff line
@@ -682,6 +682,7 @@ static void rcu_flavor_sched_clock_irq(int user) 
{

	struct task_struct *t = current;



	lockdep_assert_irqs_disabled();

	if (user || rcu_is_cpu_rrupt_from_idle()) {

		rcu_note_voluntary_context_switch(current);

	}

kernel/rcu/tree_stall.h

+8 −0
Original line number Diff line number Diff line
@@ -260,6 +260,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp, unsigned long flags) 
	struct task_struct *t;

	struct task_struct *ts[8];



	lockdep_assert_irqs_disabled();

	if (!rcu_preempt_blocked_readers_cgp(rnp))

		return 0;

	pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):",
@@ -284,6 +285,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp, unsigned long flags) 
				".q"[rscr.rs.b.need_qs],

				".e"[rscr.rs.b.exp_hint],

				".l"[rscr.on_blkd_list]);

		lockdep_assert_irqs_disabled();

		put_task_struct(t);

		ndetected++;

	}
@@ -472,6 +474,8 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) 
	struct rcu_node *rnp;

	long totqlen = 0;



	lockdep_assert_irqs_disabled();



	/* Kick and suppress, if so configured. */

	rcu_stall_kick_kthreads();

	if (rcu_stall_is_suppressed())
@@ -493,6 +497,7 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) 
				}

		}

		ndetected += rcu_print_task_stall(rnp, flags); // Releases rnp->lock.

		lockdep_assert_irqs_disabled();

	}



	for_each_possible_cpu(cpu)
@@ -538,6 +543,8 @@ static void print_cpu_stall(unsigned long gps) 
	struct rcu_node *rnp = rcu_get_root();

	long totqlen = 0;



	lockdep_assert_irqs_disabled();



	/* Kick and suppress, if so configured. */

	rcu_stall_kick_kthreads();

	if (rcu_stall_is_suppressed())
@@ -592,6 +599,7 @@ static void check_cpu_stall(struct rcu_data *rdp) 
	unsigned long js;

	struct rcu_node *rnp;



	lockdep_assert_irqs_disabled();

	if ((rcu_stall_is_suppressed() && !READ_ONCE(rcu_kick_kthreads)) ||

	    !rcu_gp_in_progress())

		return;