From: Suresh Siddha <suresh.b.siddha@intel.com>
Date: Thu, 1 Apr 2010 01:04:47 +0000 (-0700)
Subject: x86: Fix double enable_IR_x2apic() call on SMP kernel on !SMP boards
X-Git-Tag: v2.6.32.12~104
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4a10e129667758c3986835f1e733a3f4d8039de3;p=karo-tx-linux.git

x86: Fix double enable_IR_x2apic() call on SMP kernel on !SMP boards

commit 472a474c6630efd195d3738339fd1bdc8aa3b1aa upstream.

Jan Grossmann reported kernel boot panic while booting SMP
kernel on his system with a single core cpu. SMP kernels call
enable_IR_x2apic() from native_smp_prepare_cpus() and on
platforms where the kernel doesn't find SMP configuration we
ended up again calling enable_IR_x2apic() from the
APIC_init_uniprocessor() call in the smp_sanity_check(). Thus
leading to kernel panic.

Don't call enable_IR_x2apic() and default_setup_apic_routing()
from APIC_init_uniprocessor() in CONFIG_SMP case.

NOTE: this kind of non-idempotent and assymetric initialization
sequence is rather fragile and unclean, we'll clean that up
in v2.6.35. This is the minimal fix for v2.6.34.

Reported-by: Jan.Grossmann@kielnet.net
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <jbarnes@virtuousgeek.org>
Cc: <david.woodhouse@intel.com>
Cc: <weidong.han@intel.com>
Cc: <youquan.song@intel.com>
Cc: <Jan.Grossmann@kielnet.net>
LKML-Reference: <1270083887.7835.78.camel@sbs-t61.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 0e69e1789604..168e172c53db 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1664,8 +1664,10 @@ int __init APIC_init_uniprocessor(void)
 	}
 #endif
 
+#ifndef CONFIG_SMP
 	enable_IR_x2apic();
 	default_setup_apic_routing();
+#endif
 
 	verify_local_APIC();
 	connect_bsp_APIC();