futex: Allow for compiling out PI support

This makes it possible to preserve basic futex support and compile out the
PI support when RT mutexes are not available.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <dvhart@infradead.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1708010024190.5981@knanqh.ubzr

1 files changed, 29 insertions, 0 deletions

diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 72ad45a9a794..8d039b928d61 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -40,6 +40,9 @@ struct rt_mutex_waiter {
 /*
  * Various helpers to access the waiters-tree:
  */
+
+#ifdef CONFIG_RT_MUTEXES
+
 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
 {
         return !RB_EMPTY_ROOT(&lock->waiters);
@@ -69,6 +72,32 @@ task_top_pi_waiter(struct task_struct *p)
                         pi_tree_entry);
 }
 
+#else
+
+static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
+{
+        return false;
+}
+
+static inline struct rt_mutex_waiter *
+rt_mutex_top_waiter(struct rt_mutex *lock)
+{
+        return NULL;
+}
+
+static inline int task_has_pi_waiters(struct task_struct *p)
+{
+        return false;
+}
+
+static inline struct rt_mutex_waiter *
+task_top_pi_waiter(struct task_struct *p)
+{
+        return NULL;
+}
+
+#endif
+
 /*
  * lock->owner state tracking:
  */