linux-kernel - [RFC Patch Part1 V1 08/30] x86, ACPI, irq: fix possible eror in GSI to IRQ mapping for legacy IRQ

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Message-Id: <1400227550-5935-9-git-send-email-jiang.liu@linux.intel.com>
Date:	Fri, 16 May 2014 16:05:28 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	x86@...nel.org
Cc:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, sfi-devel@...plefirmware.org,
	linux-pm@...r.kernel.org
Subject: [RFC Patch Part1 V1 08/30] x86, ACPI, irq: fix possible eror in GSI to IRQ mapping for legacy IRQ

A default identity mapping between GSI and IRQ is built for legacy IRQs.
So when overriding the default identity mapping for legacy IRQs,
we should also invalidate isa_irq_to_gsi[gsi] when setting
isa_irq_to_gsi[irq] = gsi.  Otherwise there may be two entries with the
same GSI in the isa_irq_to_gsi array, and acpi_isa_irq_to_gsi() may give
wrong result.

Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
---
 arch/x86/kernel/acpi/boot.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8b8ff786af12..dccf9e88db30 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -508,7 +508,8 @@ EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
 
 int acpi_isa_irq_to_gsi(unsigned isa_irq, u32 *gsi)
 {
-	if (isa_irq < NR_IRQS_LEGACY) {
+	if (isa_irq < NR_IRQS_LEGACY &&
+	    isa_irq_to_gsi[isa_irq] != ACPI_INVALID_GSI) {
 		*gsi = isa_irq_to_gsi[isa_irq];
 		return 0;
 	}
@@ -913,6 +914,13 @@ static void __init mp_override_legacy_irq(u8 bus_irq, u8 polarity, u8 trigger,
 
 	mp_save_irq(&mp_irq);
 
+	/*
+	 * Reset default identity mapping if gsi is also an legacy IRQ,
+	 * otherwise there will be more than one entry with the same GSI
+	 * and acpi_isa_irq_to_gsi() may give wrong result.
+	 */
+	if (gsi < NR_IRQS_LEGACY && isa_irq_to_gsi[gsi] == gsi)
+		isa_irq_to_gsi[gsi] = ACPI_INVALID_GSI;
 	isa_irq_to_gsi[bus_irq] = gsi;
 }
 
-- 
1.7.10.4

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