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rcu: Assume rcu_report_dead() is always called locally

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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: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
This commit is contained in:
Frederic Weisbecker 2023-09-08 22:35:59 +02:00
parent 358662a961
commit c964c1f5ee
4 changed files with 5 additions and 5 deletions
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2
arch/arm64/kernel/smp.c
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@ -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);

2
include/linux/rcupdate.h
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@ -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

2
kernel/cpu.c
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@ -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

4
kernel/rcu/tree.c
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@ -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. */
/*