linux-kernel - [PATCH v2 4/6] arm: Mark the recheduling IPI as raw interrupt

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Message-Id: <20201124141449.572446-5-maz@kernel.org>
Date:   Tue, 24 Nov 2020 14:14:47 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     LAK <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Cc:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Valentin Schneider <Valentin.Schneider@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@....linux.org.uk>,
        Android Kernel Team <kernel-team@...roid.com>
Subject: [PATCH v2 4/6] arm: Mark the recheduling IPI as raw interrupt

Flag the rescheduling IPI as 'raw', making sure such interrupt
skips both tick management  and irqtime accounting.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 arch/arm/Kconfig      | 1 +
 arch/arm/kernel/smp.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index fe2f17eb2b50..a5e3e9963ba4 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -50,6 +50,7 @@ config ARM
 	select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
 	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
 	select GENERIC_IRQ_IPI if SMP
+	select ARCH_WANTS_IRQ_RAW if GENERIC_IRQ_IPI
 	select GENERIC_CPU_AUTOPROBE
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_IDLE_POLL_SETUP
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 48099c6e1e4a..0e09c8320caf 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -738,6 +738,10 @@ void __init set_smp_ipi_range(int ipi_base, int n)
 
 		ipi_desc[i] = irq_to_desc(ipi_base + i);
 		irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
+
+		/* The recheduling IPI is special... */
+		if (i == IPI_RESCHEDULE)
+			__irq_modify_status(ipi_base + i, 0, IRQ_RAW, ~0);
 	}
 
 	ipi_irq_base = ipi_base;
-- 
2.28.0