From: Andi Kleen <ak@suse.de>
Date: Thu, 7 Dec 2006 01:14:07 +0000 (+0100)
Subject: [PATCH] x86-64: Fix race in IO-APIC routing entry setup.
X-Git-Tag: v3.12-rc1~32283^2~14^2~16^2~82
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=516d2836434d279fef164bb1b964e83425d312d2;p=kernel%2Fkernel-generic.git

[PATCH] x86-64: Fix race in IO-APIC routing entry setup.

Interrupt could happen between setting the IO-APIC entry
and setting its interrupt data.

Pointed out by Linus.

Signed-off-by: Andi Kleen <ak@suse.de>
---

diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index 88fcc4e..eaf0b70 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -174,14 +174,20 @@ static struct IO_APIC_route_entry ioapic_read_entry(int apic, int pin)
  * the interrupt, and we need to make sure the entry is fully populated
  * before that happens.
  */
-static void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
+static void
+__ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
 {
-	unsigned long flags;
 	union entry_union eu;
 	eu.entry = e;
-	spin_lock_irqsave(&ioapic_lock, flags);
 	io_apic_write(apic, 0x11 + 2*pin, eu.w2);
 	io_apic_write(apic, 0x10 + 2*pin, eu.w1);
+}
+
+static void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&ioapic_lock, flags);
+	__ioapic_write_entry(apic, pin, e);
 	spin_unlock_irqrestore(&ioapic_lock, flags);
 }