Re: [RFC PATCH v2 5/8] irq_work: Trace self-IPIs sent via arch_irq_work_raise()

Peter Zijlstra
2022-11-17T09:11:16Z

On Wed, Nov 02, 2022 at 06:33:33PM +0000, Valentin Schneider wrote:
> IPIs sent to remove CPUs via irq_work_queue_on() are now covered by
> trace_ipi_send_cpumask(), add another instance of the tracepoint to cover
> self-IPIs.
>
> Signed-off-by: Valentin Schneider <vschneid@redhat.com>
> ---
> kernel/irq_work.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/irq_work.c b/kernel/irq_work.c
> index 7afa40fe5cc43..aec38c294ce68 100644
> --- a/kernel/irq_work.c
> +++ b/kernel/irq_work.c
> @@ -22,6 +22,8 @@
> #include <asm/processor.h>
> #include <linux/kasan.h>
>
> +#include <trace/events/ipi.h>
> +
> static DEFINE_PER_CPU(struct llist_head, raised_list);
> static DEFINE_PER_CPU(struct llist_head, lazy_list);
> static DEFINE_PER_CPU(struct task_struct *, irq_workd);
> @@ -74,6 +76,16 @@ void __weak arch_irq_work_raise(void)
> */
> }
>
> +static inline void irq_work_raise(struct irq_work *work)

__always_inline, unless you want to occasionally only see it point to
__irq_work_queue_local().

> +{
> + if (trace_ipi_send_cpumask_enabled() && arch_irq_work_has_interrupt()) {
> + trace_ipi_send_cpumask(cpumask_of(smp_processor_id()),
> + _RET_IP_,
> + work->func);
}
> +
> + arch_irq_work_raise();
> +}
> +
> /* Enqueue on current CPU, work must already be claimed and preempt disabled */
> static void __irq_work_queue_local(struct irq_work *work)
> {
> @@ -99,7 +111,7 @@ static void __irq_work_queue_local(struct irq_work *work)
>
> /* If the work is "lazy", handle it from next tick if any */
> if (!lazy_work || tick_nohz_tick_stopped())
> - arch_irq_work_raise();
> + irq_work_raise(work);
> }
>
> /* Enqueue the irq work @work on the current CPU */
> --
> 2.31.1
>