[Xen-devel] [PATCH 05/27] xen, cpu hotplug: Don't call cpu_bringup() in xen_play_dead()

["Srivatsa S. Bhat" <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>]

xen_play_dead calls cpu_bringup() which looks weird, because xen_play_dead()
is invoked in the cpu down path, whereas cpu_bringup() (as the name suggests)
is useful in the cpu bringup path.

Getting rid of xen_play_dead()'s dependency on cpu_bringup() helps in hooking
on to the generic SMP booting framework.

Also remove the extra call to preempt_enable() added by commit 41bd956
(xen/smp: Fix CPU online/offline bug triggering a BUG: scheduling while
atomic) because it becomes unnecessary after this change.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---

 arch/x86/xen/smp.c |    8 --------
 1 files changed, 0 insertions(+), 8 deletions(-)

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 09a7199..602d6b7 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -417,14 +417,6 @@ static void __cpuinit xen_play_dead(void) /* used only 
with HOTPLUG_CPU */
 {
        play_dead_common();
        HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
-       cpu_bringup();
-       /*
-        * Balance out the preempt calls - as we are running in cpu_idle
-        * loop which has been called at bootup from cpu_bringup_and_idle.
-        * The cpucpu_bringup_and_idle called cpu_bringup which made a
-        * preempt_disable() So this preempt_enable will balance it out.
-        */
-       preempt_enable();
 }
 
 #else /* !CONFIG_HOTPLUG_CPU */


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