Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86/asm changes from Ingo Molnar:
 "The one change that stands out is the alternatives patching change
  that prevents us from ever patching back instructions from SMP to UP:
  this simplifies things and speeds up CPU hotplug.

  Other than that it's smaller fixes, cleanups and improvements."

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Unspaghettize do_trap()
  x86_64: Work around old GAS bug
  x86: Use REP BSF unconditionally
  x86: Prefer TZCNT over BFS
  x86/64: Adjust types of temporaries used by ffs()/fls()/fls64()
  x86: Drop unnecessary kernel_eflags variable on 64-bit
  x86/smp: Don't ever patch back to UP if we unplug cpus

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index f58dca7a6e52..353c50f18702 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -377,7 +377,8 @@ static int __cpuinit xen_cpu_up(unsigned int cpu, struct task_struct *idle)
                 return rc;
 
         if (num_online_cpus() == 1)
-                alternatives_smp_switch(1);
+                /* Just in case we booted with a single CPU. */
+                alternatives_enable_smp();
 
         rc = xen_smp_intr_init(cpu);
         if (rc)
@@ -424,9 +425,6 @@ static void xen_cpu_die(unsigned int cpu)
         unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
         xen_uninit_lock_cpu(cpu);
         xen_teardown_timer(cpu);
-
-        if (num_online_cpus() == 1)
-                alternatives_smp_switch(0);
 }
 
 static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */