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rcu: Let dump_cpu_task() be used without preemption disabled

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The commit 2d7f00b2f0 ("rcu: Suppress smp_processor_id() complaint
in synchronize_rcu_expedited_wait()") disabled preemption around
dump_cpu_task() to suppress warning on its usage within preemtible context.

Calling dump_cpu_task() doesn't required to be in non-preemptible context
except for suppressing the smp_processor_id() warning.
As the smp_processor_id() is evaluated along with in_hardirq()
to check if it's in interrupt context, this patch removes the need
for its preemtion disablement by reordering the condition so that
smp_processor_id() only gets evaluated when it's in interrupt context.

Signed-off-by: Ryo Takakura <takakura@valinux.co.jp>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
This commit is contained in:
Ryo Takakura 2024-06-28 13:18:26 +09:00 committed by Neeraj Upadhyay
parent 7c72dedb00
commit 51b739990c
2 changed files with 1 additions and 3 deletions
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2
kernel/rcu/tree_exp.h
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@ -597,9 +597,7 @@ static void synchronize_rcu_expedited_stall(unsigned long jiffies_start, unsigne
mask = leaf_node_cpu_bit(rnp, cpu);
if (!(READ_ONCE(rnp->expmask) & mask))
continue;
preempt_disable(); // For smp_processor_id() in dump_cpu_task().
dump_cpu_task(cpu);
preempt_enable();
}
rcu_exp_print_detail_task_stall_rnp(rnp);
}

2
kernel/sched/core.c
View File

@ -9726,7 +9726,7 @@ struct cgroup_subsys cpu_cgrp_subsys = {
void dump_cpu_task(int cpu)
{
if (cpu == smp_processor_id() && in_hardirq()) {
if (in_hardirq() && cpu == smp_processor_id()) {
struct pt_regs *regs;
regs = get_irq_regs();