[PATCH] futex: add missing rtmutex.h include

[Christian König]

Since this isn't included here any more since the removal of ww_mutex.h
from seqlock.h which causes a build break.

Signed-off-by: Christian König <christian.koenig at amd.com>
Fixes: 63e8768b2ad9 ("seqlock: drop seqcount_ww_mutex_t")
---
 kernel/futex/futex.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h
index c264cbeab71c..b5379c0e6d6d 100644
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -3,6 +3,7 @@
 #define _FUTEX_H
 
 #include <linux/futex.h>
+#include <linux/rtmutex.h>
 #include <linux/sched/wake_q.h>
 
 #ifdef CONFIG_PREEMPT_RT
-- 
2.25.1