Messages in this thread | | | Date | Tue, 28 Sep 2021 10:10:53 +0100 | From | Mark Rutland <> | Subject | Re: [PATCHv2 4/5] irqchip/GICv3: let gic_handle_irq() utilize irqentry on arm64 |
| |
On Fri, Sep 24, 2021 at 09:28:36PM +0800, Pingfan Liu wrote: > The call to rcu_irq_enter() originated from gic_handle_irq() is > redundant now, since arm64 has enter_from_kernel_mode() akin to > irqenter_entry(), which has already called rcu_irq_enter().
Here I think you're referring to the call in handle_domain_irq(), but that isn't clear from the commit message.
> Based on code analysis, the redundant can raise some mistake, e.g. > rcu_data->dynticks_nmi_nesting inc 2, which causes > rcu_is_cpu_rrupt_from_idle() unexpected. > > So eliminate the call to irq_enter() in handle_domain_irq(). And > accordingly supplementing irq_enter_rcu().
We support many more irqchips on arm64, and GICv3 can be used on regular 32-bit arm, so this isn't right. Moving the irq_enter_rcu() call into the GICv3 driver specifically breaks other drivers on arm64 by removing the call, and breaks the GICv3 driver on arm by adding a duplicate call.
It looks like this should live in do_interrupt_handler() in arch/arm64/kernel/entry-common.c, e.g.
| static void do_interrupt_handler(struct pt_regs *regs, | void (*handler)(struct pt_regs *)) | { | irq_enter_rcu(); | if (on_thread_stack()) | call_on_irq_stack(regs, handler); | else | handler(regs); | irq_exit_rcu(); | }
... unless there's some problem with that?
Thanks, Mark.
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Marc Zyngier <maz@kernel.org> > Cc: Joey Gouly <joey.gouly@arm.com> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Julien Thierry <julien.thierry@arm.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Yuichi Ito <ito-yuichi@fujitsu.com> > Cc: linux-kernel@vger.kernel.org > To: linux-arm-kernel@lists.infradead.org > --- > arch/arm64/Kconfig | 1 + > drivers/irqchip/irq-gic-v3.c | 2 ++ > 2 files changed, 3 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 5c7ae4c3954b..d29bae38a951 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -98,6 +98,7 @@ config ARM64 > select ARCH_HAS_UBSAN_SANITIZE_ALL > select ARM_AMBA > select ARM_ARCH_TIMER > + select HAVE_ARCH_IRQENTRY > select ARM_GIC > select AUDIT_ARCH_COMPAT_GENERIC > select ARM_GIC_V2M if PCI > diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c > index 89dcec902a82..906538fa8771 100644 > --- a/drivers/irqchip/irq-gic-v3.c > +++ b/drivers/irqchip/irq-gic-v3.c > @@ -729,10 +729,12 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs > else > isb(); > > + irq_enter_rcu(); > if (handle_domain_irq(gic_data.domain, irqnr, regs)) { > WARN_ONCE(true, "Unexpected interrupt received!\n"); > gic_deactivate_unhandled(irqnr); > } > + irq_exit_rcu(); > } > > static u32 gic_get_pribits(void) > -- > 2.31.1 >
| |