hrtimers: simplify lockdep handling

In order to avoid the false positive from lockdep, each per-cpu base->lock has
the separate lock class and migrate_hrtimers() uses double_spin_lock().

This is overcomplicated: except for migrate_hrtimers() we never take 2 locks
at once, and migrate_hrtimers() can use spin_lock_nested().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 4 insertions, 5 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 911e87d0440d..c642ef75069f 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1424,7 +1424,6 @@ static void __cpuinit init_hrtimers_cpu(int cpu)
         int i;
 
         spin_lock_init(&cpu_base->lock);
-        lockdep_set_class(&cpu_base->lock, &cpu_base->lock_key);
 
         for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
                 cpu_base->clock_base[i].cpu_base = cpu_base;
@@ -1465,16 +1464,16 @@ static void migrate_hrtimers(int cpu)
         tick_cancel_sched_timer(cpu);
 
         local_irq_disable();
-        double_spin_lock(&new_base->lock, &old_base->lock,
-                         smp_processor_id() < cpu);
+        spin_lock(&new_base->lock);
+        spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
 
         for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
                 migrate_hrtimer_list(&old_base->clock_base[i],
                                      &new_base->clock_base[i]);
         }
 
-        double_spin_unlock(&new_base->lock, &old_base->lock,
-                           smp_processor_id() < cpu);
+        spin_unlock(&old_base->lock);
+        spin_unlock(&new_base->lock);
         local_irq_enable();
         put_cpu_var(hrtimer_bases);
 }