clockevents: Serialize calls to clockevents_update_freq() in the core

We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 19 insertions, 6 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 43780ab5e279..003e6c3663b1 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -120,6 +120,19 @@ int tick_is_broadcast_device(struct clock_event_device *dev)
         return (dev && tick_broadcast_device.evtdev == dev);
 }
 
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
+{
+        int ret = -ENODEV;
+
+        if (tick_is_broadcast_device(dev)) {
+                raw_spin_lock(&tick_broadcast_lock);
+                ret = __clockevents_update_freq(dev, freq);
+                raw_spin_unlock(&tick_broadcast_lock);
+        }
+        return ret;
+}
+
+
 static void err_broadcast(const struct cpumask *mask)
 {
         pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
@@ -272,12 +285,8 @@ static void tick_do_broadcast(struct cpumask *mask)
  */
 static void tick_do_periodic_broadcast(void)
 {
-        raw_spin_lock(&tick_broadcast_lock);
-
         cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
         tick_do_broadcast(tmpmask);
-
-        raw_spin_unlock(&tick_broadcast_lock);
 }
 
 /*
@@ -287,13 +296,15 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 {
         ktime_t next;
 
+        raw_spin_lock(&tick_broadcast_lock);
+
         tick_do_periodic_broadcast();
 
         /*
          * The device is in periodic mode. No reprogramming necessary:
          */
         if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
-                return;
+                goto unlock;
 
         /*
          * Setup the next period for devices, which do not have
@@ -306,9 +317,11 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
                 next = ktime_add(next, tick_period);
 
                 if (!clockevents_program_event(dev, next, false))
-                        return;
+                        goto unlock;
                 tick_do_periodic_broadcast();
         }
+unlock:
+        raw_spin_unlock(&tick_broadcast_lock);
 }
 
 /*