[SPARC64]: Fix memory controller register access when non-SMP.

get_cpu() always returns zero on non-SMP builds, but we
really want the physical cpu number in this code in order
to do the right thing.

Based upon a non-SMP kernel boot failure report from Bernd Zeimetz.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 6 deletions

diff --git a/arch/sparc64/kernel/chmc.c b/arch/sparc64/kernel/chmc.c
index 777d34577045..6d4f02e8a4cf 100644
--- a/arch/sparc64/kernel/chmc.c
+++ b/arch/sparc64/kernel/chmc.c
@@ -1,7 +1,6 @@
-/* $Id: chmc.c,v 1.4 2002/01/08 16:00:14 davem Exp $
- * memctrlr.c: Driver for UltraSPARC-III memory controller.
+/* memctrlr.c: Driver for UltraSPARC-III memory controller.
  *
- * Copyright (C) 2001 David S. Miller (davem@redhat.com)
+ * Copyright (C) 2001, 2007 David S. Miller (davem@davemloft.net)
  */
 
 #include <linux/module.h>
@@ -16,6 +15,7 @@
 #include <linux/init.h>
 #include <asm/spitfire.h>
 #include <asm/chmctrl.h>
+#include <asm/cpudata.h>
 #include <asm/oplib.h>
 #include <asm/prom.h>
 #include <asm/io.h>
@@ -242,8 +242,11 @@ int chmc_getunumber(int syndrome_code,
  */
 static u64 read_mcreg(struct mctrl_info *mp, unsigned long offset)
 {
-        unsigned long ret;
-        int this_cpu = get_cpu();
+        unsigned long ret, this_cpu;
+
+        preempt_disable();
+
+        this_cpu = real_hard_smp_processor_id();
 
         if (mp->portid == this_cpu) {
                 __asm__ __volatile__("ldxa      [%1] %2, %0"
@@ -255,7 +258,8 @@ static u64 read_mcreg(struct mctrl_info *mp, unsigned long offset)
                                      : "r" (mp->regs + offset),
                                        "i" (ASI_PHYS_BYPASS_EC_E));
         }
-        put_cpu();
+
+        preempt_enable();
 
         return ret;
 }