x86/core, x86/xen/smp: Use 'die_complete' completion when taking CPU down

Commit 2ed53c0d6cc9 ("x86/smpboot: Speed up suspend/resume by
avoiding 100ms sleep for CPU offline during S3") introduced
completions to CPU offlining process. These completions are not
initialized on Xen kernels causing a panic in
play_dead_common().

Move handling of die_complete into common routines to make them
available to Xen guests.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: tianyu.lan@intel.com
Cc: konrad.wilk@oracle.com
Cc: xen-devel@lists.xenproject.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414770572-7950-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 15 insertions, 4 deletions

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 8cd27e08e23c..8cd1cc3bc835 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -150,6 +150,7 @@ static inline void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 }
 
 void cpu_disable_common(void);
+void cpu_die_common(unsigned int cpu);
 void native_smp_prepare_boot_cpu(void);
 void native_smp_prepare_cpus(unsigned int max_cpus);
 void native_smp_cpus_done(unsigned int max_cpus);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 4d2128ac70bd..668d8f2a8781 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1303,10 +1303,14 @@ static void __ref remove_cpu_from_maps(int cpu)
         numa_remove_cpu(cpu);
 }
 
+static DEFINE_PER_CPU(struct completion, die_complete);
+
 void cpu_disable_common(void)
 {
         int cpu = smp_processor_id();
 
+        init_completion(&per_cpu(die_complete, smp_processor_id()));
+
         remove_siblinginfo(cpu);
 
         /* It's now safe to remove this processor from the online map */
@@ -1316,8 +1320,6 @@ void cpu_disable_common(void)
         fixup_irqs();
 }
 
-static DEFINE_PER_CPU(struct completion, die_complete);
-
 int native_cpu_disable(void)
 {
         int ret;
@@ -1327,16 +1329,21 @@ int native_cpu_disable(void)
                 return ret;
 
         clear_local_APIC();
-        init_completion(&per_cpu(die_complete, smp_processor_id()));
         cpu_disable_common();
 
         return 0;
 }
 
+void cpu_die_common(unsigned int cpu)
+{
+        wait_for_completion_timeout(&per_cpu(die_complete, cpu), HZ);
+}
+
 void native_cpu_die(unsigned int cpu)
 {
         /* We don't do anything here: idle task is faking death itself. */
-        wait_for_completion_timeout(&per_cpu(die_complete, cpu), HZ);
+
+        cpu_die_common(cpu);
 
         /* They ack this in play_dead() by setting CPU_DEAD */
         if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 8650cdb53209..4c071aeb8417 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -510,6 +510,9 @@ static void xen_cpu_die(unsigned int cpu)
                 current->state = TASK_UNINTERRUPTIBLE;
                 schedule_timeout(HZ/10);
         }
+
+        cpu_die_common(cpu);
+
         xen_smp_intr_free(cpu);
         xen_uninit_lock_cpu(cpu);
         xen_teardown_timer(cpu);