Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 9d406cdc847f..071ff4798236 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -140,6 +140,9 @@ static int enable_single_step(struct task_struct *child)
  */
 static void write_debugctlmsr(struct task_struct *child, unsigned long val)
 {
+        if (child->thread.debugctlmsr == val)
+                return;
+
         child->thread.debugctlmsr = val;
 
         if (child != current)
@@ -165,11 +168,11 @@ static void enable_step(struct task_struct *child, bool block)
                 write_debugctlmsr(child,
                                   child->thread.debugctlmsr | DEBUGCTLMSR_BTF);
         } else {
-            write_debugctlmsr(child,
-                              child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
+                write_debugctlmsr(child,
+                                  child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
 
-            if (!child->thread.debugctlmsr)
-                    clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
+                if (!child->thread.debugctlmsr)
+                        clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
         }
 }