From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@armlinux.org.uk (Russell King - ARM Linux) Date: Mon, 14 Nov 2016 15:36:30 +0000 Subject: [PATCH RFC 3/2] ARM: improve arch_irq_work_has_interrupt() In-Reply-To: References: Message-ID: <20161114153630.GN1041@n2100.armlinux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Following on from the previous patch, I think this makes more sense to determine whether we can support IRQ work interrupts. Whether we can support them or not depends on two things: (a) whether the kernel has support for receiving IPIs (b) whether it's possible to send an IPI to CPUs including the raising CPU. (a) is a function of how the kernel is built - and in the case of ARM, it depends whether the kernel is built with SMP enabled or not. (b) is a property of the interrupt controller. It hasn't ever been a function of the CPU or architecture. Commit 059e232089e4 ("irqchip/gic: Allow self-SGIs for SMP on UP configurations") changes the GIC IPI code such that we can raise SGIs on uniprocessor systems running on a SMP kernel, which means we can support IRQ work interrupts here as well. So, we shouldn't be using cpu_smp() (or its previous is_smp() here at all. Use a flag to indicate whether we can IPI and use that to indicate whether we support irq work interrupts. Signed-off-by: Russell King --- arch/arm/include/asm/irq_work.h | 11 +++++++++-- arch/arm/kernel/irq.c | 0 arch/arm/kernel/smp.c | 3 +++ drivers/irqchip/irq-gic.c | 17 +++++++++++++---- 4 files changed, 25 insertions(+), 6 deletions(-) diff --git a/arch/arm/include/asm/irq_work.h b/arch/arm/include/asm/irq_work.h index 2dc8d7995b48..d7262a3c2f2e 100644 --- a/arch/arm/include/asm/irq_work.h +++ b/arch/arm/include/asm/irq_work.h @@ -1,11 +1,18 @@ #ifndef __ASM_ARM_IRQ_WORK_H #define __ASM_ARM_IRQ_WORK_H -#include +extern bool irq_controller_can_ipi; +#define irq_controller_can_ipi irq_controller_can_ipi static inline bool arch_irq_work_has_interrupt(void) { - return cpu_smp(); +#ifdef CONFIG_SMP + /* This depends on the IRQ controller */ + return irq_controller_can_ipi; +#else + /* The kernel is not built to support IPIs */ + return false; +#endif } #endif /* _ASM_ARM_IRQ_WORK_H */ diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 7dd14e8395e6..1fa9412cc4aa 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -473,6 +473,9 @@ void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int)) __smp_cross_call = fn; } +/* This indicates whether the IRQ controller can IPI (including self-IPI) */ +bool irq_controller_can_ipi; + static const char *ipi_types[NR_IPI] __tracepoint_string = { #define S(x,s) [x] = s S(IPI_WAKEUP, "CPU wakeup interrupts"), diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index d6c404b3584d..abe8d5807c0f 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -1187,9 +1187,6 @@ static int __init __gic_init_bases(struct gic_chip_data *gic, */ for (i = 0; i < NR_GIC_CPU_IF; i++) gic_cpu_map[i] = 0xff; -#ifdef CONFIG_SMP - set_smp_cross_call(gic_raise_softirq); -#endif cpuhp_setup_state_nocalls(CPUHP_AP_IRQ_GIC_STARTING, "AP_IRQ_GIC_STARTING", gic_starting_cpu, NULL); @@ -1207,8 +1204,20 @@ static int __init __gic_init_bases(struct gic_chip_data *gic, } ret = gic_init_bases(gic, irq_start, handle); - if (ret) + if (ret) { kfree(name); + return ret; + } + + if (gic == &gic_data[0]) { +#ifdef CONFIG_SMP + set_smp_cross_call(gic_raise_softirq); +#ifdef irq_controller_can_ipi + if (nr_cpu_ids == 1 || hweight8(gic_cpu_map[0]) == 1) + irq_controller_can_ipi = true; +#endif +#endif + } return ret; } -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently@9.6Mbps down 400kbps up according to speedtest.net.