From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 21 Sep 2017 14:39:56 +0200
Subject: rt/locking: allow recursive local_trylock()
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 40cf995cde2a9f3a2433f4f71d46bdff964f3003
Patch-mainline: Queued in subsystem maintainer repository
References: SLE12 Realtime Extension

required for following networking patch which does recursive try-lock.
While at it, add the !RT version of it because it did not yet exist.

Cc: rt-stable@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 include/linux/locallock.h |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/include/linux/locallock.h
+++ b/include/linux/locallock.h
@@ -61,6 +61,9 @@ static inline int __local_trylock(struct
 		lv->owner = current;
 		lv->nestcnt = 1;
 		return 1;
+	} else if (lv->owner == current) {
+		lv->nestcnt++;
+		return 1;
 	}
 	return 0;
 }
@@ -234,6 +237,12 @@ static inline int __local_unlock_irqrest
 
 static inline void local_irq_lock_init(int lvar) { }
 
+#define local_trylock(lvar)					\
+	({							\
+		preempt_disable();				\
+		1;						\
+	})
+
 #define local_lock(lvar)			preempt_disable()
 #define local_unlock(lvar)			preempt_enable()
 #define local_lock_irq(lvar)			local_irq_disable()