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 <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> --- arch/arm64/kernel/smp.c | 2 +- include/linux/rcupdate.h | 2 +- kernel/cpu.c | 2 +- kernel/rcu/tree.c | 4 ++-- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 960b98b43506..8fa646c90c67 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -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); diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 5e5f920ade90..aa351ddcbe8d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -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 diff --git a/kernel/cpu.c b/kernel/cpu.c index 6de7c6bb74ee..076e75fed8bb 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -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 diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8c2954502e55..2e1e7eadf2cc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -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. */ /* -- 2.34.1
