x86-64: survive having no irq mapping for a vector

Occasionally the kernel has bugs that result in no irq being found for a
given cpu vector.  If we acknowledge the irq the system has a good chance
of continuing even though we dropped an irq message.  If we continue to
simply print a message and not acknowledge the irq the system is likely to
become non-responsive shortly there after.

AK: Fixed compilation for UP kernels

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: "Luigi Genoni" <luigi.genoni@pirelli.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
index 0c06af6c13bcb6c4d4e8331da76279442ce378a3..3bc30d2c13d3289809cd538f07cef4fc8033c0dc 100644 (file)
--- a/arch/x86_64/kernel/irq.c
+++ b/arch/x86_64/kernel/irq.c
@@ -18,6 +18,7 @@
 #include <asm/uaccess.h>
 #include <asm/io_apic.h>
 #include <asm/idle.h>
+#include <asm/smp.h>
 
 atomic_t irq_err_count;
 
@@ -120,9 +121,14 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
 
        if (likely(irq < NR_IRQS))
                generic_handle_irq(irq);
-       else if (printk_ratelimit())
-               printk(KERN_EMERG "%s: %d.%d No irq handler for vector\n",
-                       __func__, smp_processor_id(), vector);
+       else {
+               if (!disable_apic)
+                       ack_APIC_irq();
+
+               if (printk_ratelimit())
+                       printk(KERN_EMERG "%s: %d.%d No irq handler for vector\n",
+                               __func__, smp_processor_id(), vector);
+       }
 
        irq_exit();