Commit c964c1f5 authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

rcu: Assume rcu_report_dead() is always called locally 



rcu_report_dead() has to be called locally by the CPU that is going to
exit the RCU state machine. Passing a cpu argument here is error-prone
and leaves the possibility for a racy remote call.

Use local access instead.

Reviewed-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
parent 358662a9

arch/arm64/kernel/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -401,7 +401,7 @@ void __noreturn cpu_die_early(void) 


	/* Mark this CPU absent */

	set_cpu_present(cpu, 0);

	rcu_report_dead(cpu);

	rcu_report_dead();



	if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {

		update_cpu_boot_status(CPU_KILL_ME);

include/linux/rcupdate.h

+1 −1
Original line number Diff line number Diff line
@@ -122,7 +122,7 @@ static inline void call_rcu_hurry(struct rcu_head *head, rcu_callback_t func) 
void rcu_init(void);

extern int rcu_scheduler_active;

void rcu_sched_clock_irq(int user);

void rcu_report_dead(unsigned int cpu);

void rcu_report_dead(void);

void rcutree_migrate_callbacks(int cpu);



#ifdef CONFIG_TASKS_RCU_GENERIC

kernel/cpu.c

+1 −1
Original line number Diff line number Diff line
@@ -1388,7 +1388,7 @@ void cpuhp_report_idle_dead(void) 
	struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);



	BUG_ON(st->state != CPUHP_AP_OFFLINE);

	rcu_report_dead(smp_processor_id());

	rcu_report_dead();

	st->state = CPUHP_AP_IDLE_DEAD;

	/*

	 * We cannot call complete after rcu_report_dead() so we delegate it

kernel/rcu/tree.c

+2 −2
Original line number Diff line number Diff line
@@ -4560,11 +4560,11 @@ void rcu_cpu_starting(unsigned int cpu) 
 * from the outgoing CPU rather than from the cpuhp_step mechanism.

 * This is because this function must be invoked at a precise location.

 */

void rcu_report_dead(unsigned int cpu)

void rcu_report_dead(void)

{

	unsigned long flags;

	unsigned long mask;

	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);

	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);

	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */



	/*