On Mon, 19 Sept 2022 at 12:18, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> None of these functions should ever be ran with RCU disabled anymore.
>
> Specifically, do_handle_IPI() is only called from handle_IPI() which
> explicitly does irq_enter()/irq_exit() which ensures RCU is watching.
>
> The problem with smp_cross_call() was, per commit 7c64cc0531fa ("arm: Use
> _rcuidle for smp_cross_call() tracepoints"), that
> cpuidle_enter_state_coupled() already had RCU disabled, but that's
> long been fixed by commit 1098582a0f6c ("sched,idle,rcu: Push rcu_idle
> deeper into the idle path").
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
FWIW:
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Kind regards
Uffe
> ---
> arch/arm/kernel/smp.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -639,7 +639,7 @@ static void do_handle_IPI(int ipinr)
> unsigned int cpu = smp_processor_id();
>
> if ((unsigned)ipinr < NR_IPI)
> - trace_ipi_entry_rcuidle(ipi_types[ipinr]);
> + trace_ipi_entry(ipi_types[ipinr]);
>
> switch (ipinr) {
> case IPI_WAKEUP:
> @@ -686,7 +686,7 @@ static void do_handle_IPI(int ipinr)
> }
>
> if ((unsigned)ipinr < NR_IPI)
> - trace_ipi_exit_rcuidle(ipi_types[ipinr]);
> + trace_ipi_exit(ipi_types[ipinr]);
> }
>
> /* Legacy version, should go away once all irqchips have been converted */
> @@ -709,7 +709,7 @@ static irqreturn_t ipi_handler(int irq,
>
> static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
> {
> - trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
> + trace_ipi_raise(target, ipi_types[ipinr]);
> __ipi_send_mask(ipi_desc[ipinr], target);
> }
>
>
>
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