[PATCH] i386: 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/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 3b7a63e0ed1a5b07121ae63c9e35863ae0469a2b..e33b7a8452993557bef5a23f8c6bb0a9505fbf2a 100644 (file)
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -153,14 +153,20 @@ 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);
 }
 
@@ -1360,8 +1366,8 @@ static void __init setup_IO_APIC_irqs(void)
                        if (!apic && (irq < 16))
                                disable_8259A_irq(irq);
                }
-               ioapic_write_entry(apic, pin, entry);
                spin_lock_irqsave(&ioapic_lock, flags);
+               __ioapic_write_entry(apic, pin, entry);
                set_native_irq_info(irq, TARGET_CPUS);
                spin_unlock_irqrestore(&ioapic_lock, flags);
        }
@@ -2856,8 +2862,8 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
        if (!ioapic && (irq < 16))
                disable_8259A_irq(irq);
 
-       ioapic_write_entry(ioapic, pin, entry);
        spin_lock_irqsave(&ioapic_lock, flags);
+       __ioapic_write_entry(ioapic, pin, entry);
        set_native_irq_info(irq, TARGET_CPUS);
        spin_unlock_irqrestore(&ioapic_lock, flags);