linux-kernel - Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is

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Date:	Fri, 06 Jun 2014 13:53:01 -0400
From:	Pranith Kumar <pranith@...ech.edu>
To:	peterz@...radead.org
CC:	linux-kernel@...r.kernel.org, tim.c.chen@...ux.intel.com,
	davidlohr@...com, mingo@...hat.com
Subject: Re: [RFC PATCH 1/1] cleanup: use bool as return type for rwsem_is_locked

On Fri, Jun 6, 2014 at 3:35 AM, Peter Zijlstra <peterz@...radead.org> wrote:
>
> Now in general, I don't particularly like such superfluous changes, so
> unless you can show that GCC actually generates better code, I'd prefer
> to keep things as they are.

Fixed and checked the assembly. It saves us 2 bytes of code, not much. I am not sure if that is worth it :(

use bool as the return type for rwsem_is_locked() instead of int

Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
 include/linux/rwsem-spinlock.h  |    2 +-
 include/linux/rwsem.h           |    2 +-
 kernel/locking/rwsem-spinlock.c |    4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h
index d5b13bc..9026d2a 100644
--- a/include/linux/rwsem-spinlock.h
+++ b/include/linux/rwsem-spinlock.h
@@ -39,7 +39,7 @@ extern int __down_write_trylock(struct rw_semaphore *sem);
 extern void __up_read(struct rw_semaphore *sem);
 extern void __up_write(struct rw_semaphore *sem);
 extern void __downgrade_write(struct rw_semaphore *sem);
-extern int rwsem_is_locked(struct rw_semaphore *sem);
+extern bool rwsem_is_locked(struct rw_semaphore *sem);
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_RWSEM_SPINLOCK_H */
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 03f3b05..b056780 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -40,7 +40,7 @@ extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
 #include <asm/rwsem.h>
 
 /* In all implementations count != 0 means locked */
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
+static inline bool rwsem_is_locked(struct rw_semaphore *sem)
 {
 	return sem->count != 0;
 }
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
index 9be8a91..3f8adf8 100644
--- a/kernel/locking/rwsem-spinlock.c
+++ b/kernel/locking/rwsem-spinlock.c
@@ -20,9 +20,9 @@ struct rwsem_waiter {
 	enum rwsem_waiter_type type;
 };
 
-int rwsem_is_locked(struct rw_semaphore *sem)
+bool rwsem_is_locked(struct rw_semaphore *sem)
 {
-	int ret = 1;
+	bool ret = true;
 	unsigned long flags;
 
 	if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) {
-- 
1.7.9.5
--
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