x86: PEBS cleanup

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ad21349..4a93c98 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -500,7 +500,6 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
 {
        struct thread_struct *prev, *next;
        unsigned long debugctl;
-       unsigned long ds_prev = 0, ds_next = 0;
 
        prev = &prev_p->thread,
        next = &next_p->thread;
@@ -508,17 +507,23 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
        debugctl = prev->debugctlmsr;
 
 #ifdef CONFIG_X86_DS
-       if (prev->ds_ctx)
-               ds_prev = (unsigned long)prev->ds_ctx->ds;
-       if (next->ds_ctx)
-               ds_next = (unsigned long)next->ds_ctx->ds;
-
-       if (ds_next != ds_prev) {
-               /* we clear debugctl to make sure DS
-                * is not in use when we change it */
-               debugctl = 0;
-               update_debugctlmsr(0);
-               wrmsrl(MSR_IA32_DS_AREA, ds_next);
+       {
+               unsigned long ds_prev = 0, ds_next = 0;
+
+               if (prev->ds_ctx)
+                       ds_prev = (unsigned long)prev->ds_ctx->ds;
+               if (next->ds_ctx)
+                       ds_next = (unsigned long)next->ds_ctx->ds;
+
+               if (ds_next != ds_prev) {
+                       /*
+                        * We clear debugctl to make sure DS
+                        * is not in use when we change it:
+                        */
+                       debugctl = 0;
+                       update_debugctlmsr(0);
+                       wrmsrl(MSR_IA32_DS_AREA, ds_next);
+               }
        }
 #endif /* CONFIG_X86_DS */