1 files changed, 26 insertions, 20 deletions

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index a071e6be177..8e740934bd1 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -10,26 +10,28 @@
 #include <linux/module.h>
 #include <linux/ptrace.h>
 #include <linux/kexec.h>
+#include <linux/sysfs.h>
 #include <linux/bug.h>
 #include <linux/nmi.h>
-#include <linux/sysfs.h>
 
 #include <asm/stacktrace.h>
 
 #include "dumpstack.h"
 
+#define N_EXCEPTION_STACKS_END \
+                (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
 
 static char x86_stack_ids[][8] = {
-                [DEBUG_STACK - 1] = "#DB",
-                [NMI_STACK - 1] = "NMI",
-                [DOUBLEFAULT_STACK - 1] = "#DF",
-                [STACKFAULT_STACK - 1] = "#SS",
-                [MCE_STACK - 1] = "#MC",
+                [ DEBUG_STACK-1                 ]       = "#DB",
+                [ NMI_STACK-1                   ]       = "NMI",
+                [ DOUBLEFAULT_STACK-1           ]       = "#DF",
+                [ STACKFAULT_STACK-1            ]       = "#SS",
+                [ MCE_STACK-1                   ]       = "#MC",
 #if DEBUG_STKSZ > EXCEPTION_STKSZ
-                [N_EXCEPTION_STACKS ...
-                        N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
+                [ N_EXCEPTION_STACKS ...
+                  N_EXCEPTION_STACKS_END        ]       = "#DB[?]"
 #endif
-        };
+};
 
 int x86_is_stack_id(int id, char *name)
 {
@@ -37,7 +39,7 @@ int x86_is_stack_id(int id, char *name)
 }
 
 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
-                                        unsigned *usedp, char **idp)
+                                         unsigned *usedp, char **idp)
 {
         unsigned k;
 
@@ -202,21 +204,24 @@ EXPORT_SYMBOL(dump_trace);
 
 void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                unsigned long *sp, unsigned long bp, char *log_lvl)
+                   unsigned long *sp, unsigned long bp, char *log_lvl)
 {
+        unsigned long *irq_stack_end;
+        unsigned long *irq_stack;
         unsigned long *stack;
+        int cpu;
         int i;
-        const int cpu = smp_processor_id();
-        unsigned long *irq_stack_end =
-                (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
-        unsigned long *irq_stack =
-                (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
+
+        preempt_disable();
+        cpu = smp_processor_id();
+
+        irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
+        irq_stack       = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
 
         /*
-         * debugging aid: "show_stack(NULL, NULL);" prints the
-         * back trace for this cpu.
+         * Debugging aid: "show_stack(NULL, NULL);" prints the
+         * back trace for this cpu:
          */
-
         if (sp == NULL) {
                 if (task)
                         sp = (unsigned long *)task->thread.sp;
@@ -240,6 +245,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
                 printk(" %016lx", *stack++);
                 touch_nmi_watchdog();
         }
+        preempt_enable();
+
         printk("\n");
         show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 }
@@ -303,4 +310,3 @@ int is_valid_bugaddr(unsigned long ip)
 
         return ud2 == 0x0b0f;
 }
-