linux-kernel - [PATCH RT] rt/locking: allow recursive local

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Message-ID: <20170921191327.3g5hkp4kvlw5ppzi@linutronix.de>
Date:   Thu, 21 Sep 2017 21:13:27 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>, tglx@...utronix.de
Subject: [PATCH RT] rt/locking: allow recursive local_trylock()

required for 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@...r.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 include/linux/locallock.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/locallock.h b/include/linux/locallock.h
index eeb1a66df402..d658c2552601 100644
--- a/include/linux/locallock.h
+++ b/include/linux/locallock.h
@@ -61,6 +61,9 @@ static inline int __local_trylock(struct local_irq_lock *lv)
 		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_irqrestore(struct local_irq_lock *lv,
 
 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()
-- 
2.14.1