x86: keep MP_intsrc_info untouched if we do not update mptable

Daniel Exner reported IO-APIC enumeration breakage in linux-next.

Alexey Starikovskiy found out that it might be related to
commit 2944e16b25 "x86: update mptable".

use enable_update_mptable to decide if need check before add mp_irqs array.

Reported-by: Daniel Exner <webmaster@dragonslave.de>
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 6 deletions

diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index b62ac6ba1410..014ac5d90f80 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -34,6 +34,8 @@
 #include <mach_mpparse.h>
 #endif
 
+int enable_update_mptable;
+
 /*
  * Checksum an MP configuration block.
  */
@@ -295,10 +297,11 @@ void MP_intsrc_info(struct mpc_config_intsrc *m)
 
         print_MP_intsrc_info(m);
 
-        for (i = 0; i < mp_irq_entries; i++) {
-                if (!mp_irq_mpc_intsrc_cmp(&mp_irqs[i], m))
-                        return;
-        }
+        if (enable_update_mptable)
+                for (i = 0; i < mp_irq_entries; i++) {
+                        if (!mp_irq_mpc_intsrc_cmp(&mp_irqs[i], m))
+                                return;
+                }
 
         assign_to_mp_irq(m, &mp_irqs[mp_irq_entries]);
         if (++mp_irq_entries == MAX_IRQ_SOURCES)
@@ -1110,8 +1113,6 @@ out:
         return 0;
 }
 
-int __initdata enable_update_mptable;
-
 static int __init update_mptable_setup(char *str)
 {
         enable_update_mptable = 1;