3 files changed, 22 insertions, 18 deletions

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 6519cf62d9cd..0e17c10f8a9d 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -685,8 +685,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
         /* Add clocksource to the clcoksource list */
         mutex_lock(&clocksource_mutex);
         clocksource_enqueue(cs);
-        clocksource_select();
         clocksource_enqueue_watchdog(cs);
+        clocksource_select();
         mutex_unlock(&clocksource_mutex);
         return 0;
 }
@@ -706,8 +706,8 @@ int clocksource_register(struct clocksource *cs)
 
         mutex_lock(&clocksource_mutex);
         clocksource_enqueue(cs);
-        clocksource_select();
         clocksource_enqueue_watchdog(cs);
+        clocksource_select();
         mutex_unlock(&clocksource_mutex);
         return 0;
 }
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index 25028dd4fa18..c340ca658f37 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -19,7 +19,6 @@
  */
 #include <linux/device.h>
 #include <linux/file.h>
-#include <linux/mutex.h>
 #include <linux/posix-clock.h>
 #include <linux/slab.h>
 #include <linux/syscalls.h>
@@ -34,19 +33,19 @@ static struct posix_clock *get_posix_clock(struct file *fp)
 {
         struct posix_clock *clk = fp->private_data;
 
-        mutex_lock(&clk->mutex);
+        down_read(&clk->rwsem);
 
         if (!clk->zombie)
                 return clk;
 
-        mutex_unlock(&clk->mutex);
+        up_read(&clk->rwsem);
 
         return NULL;
 }
 
 static void put_posix_clock(struct posix_clock *clk)
 {
-        mutex_unlock(&clk->mutex);
+        up_read(&clk->rwsem);
 }
 
 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
@@ -156,7 +155,7 @@ static int posix_clock_open(struct inode *inode, struct file *fp)
         struct posix_clock *clk =
                 container_of(inode->i_cdev, struct posix_clock, cdev);
 
-        mutex_lock(&clk->mutex);
+        down_read(&clk->rwsem);
 
         if (clk->zombie) {
                 err = -ENODEV;
@@ -172,7 +171,7 @@ static int posix_clock_open(struct inode *inode, struct file *fp)
                 fp->private_data = clk;
         }
 out:
-        mutex_unlock(&clk->mutex);
+        up_read(&clk->rwsem);
         return err;
 }
 
@@ -211,25 +210,20 @@ int posix_clock_register(struct posix_clock *clk, dev_t devid)
         int err;
 
         kref_init(&clk->kref);
-        mutex_init(&clk->mutex);
+        init_rwsem(&clk->rwsem);
 
         cdev_init(&clk->cdev, &posix_clock_file_operations);
         clk->cdev.owner = clk->ops.owner;
         err = cdev_add(&clk->cdev, devid, 1);
-        if (err)
-                goto no_cdev;
 
         return err;
-no_cdev:
-        mutex_destroy(&clk->mutex);
-        return err;
 }
 EXPORT_SYMBOL_GPL(posix_clock_register);
 
 static void delete_clock(struct kref *kref)
 {
         struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
-        mutex_destroy(&clk->mutex);
+
         if (clk->release)
                 clk->release(clk);
 }
@@ -238,9 +232,9 @@ void posix_clock_unregister(struct posix_clock *clk)
 {
         cdev_del(&clk->cdev);
 
-        mutex_lock(&clk->mutex);
+        down_write(&clk->rwsem);
         clk->zombie = true;
-        mutex_unlock(&clk->mutex);
+        up_write(&clk->rwsem);
 
         kref_put(&clk->kref, delete_clock);
 }
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index da800ffa810c..723c7637e55a 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -522,10 +522,11 @@ static void tick_broadcast_init_next_event(struct cpumask *mask,
  */
 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
 {
+        int cpu = smp_processor_id();
+
         /* Set it up only once ! */
         if (bc->event_handler != tick_handle_oneshot_broadcast) {
                 int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
-                int cpu = smp_processor_id();
 
                 bc->event_handler = tick_handle_oneshot_broadcast;
                 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
@@ -551,6 +552,15 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
                         tick_broadcast_set_event(tick_next_period, 1);
                 } else
                         bc->next_event.tv64 = KTIME_MAX;
+        } else {
+                /*
+                 * The first cpu which switches to oneshot mode sets
+                 * the bit for all other cpus which are in the general
+                 * (periodic) broadcast mask. So the bit is set and
+                 * would prevent the first broadcast enter after this
+                 * to program the bc device.
+                 */
+                tick_broadcast_clear_oneshot(cpu);
         }
 }