[PATCH] sparc, rwsem: drop superfluous arch specific implementation

From: Michal Hocko <mhocko@kernel.org>
To: "David S. Miller" <davem@davemloft.net>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
	LKML <linux-kernel@vger.kernel.org>,
	sparclinux@vger.kernel.org, linux-arch@vger.kernel.org
Subject: [PATCH] sparc, rwsem: drop superfluous arch specific implementation
Date: Wed, 6 Apr 2016 11:06:38 +0200	[thread overview]
Message-ID: <20160406090638.GB24272@dhcp22.suse.cz> (raw)
In-Reply-To: <20160402011753.GB5329@linux-uzut.site>

[Redicing CC list]

On Fri 01-04-16 18:17:53, Davidlohr Bueso wrote:
> On Fri, 01 Apr 2016, Michal Hocko wrote:
[...]
> >arch/sh/include/asm/rwsem.h     | 14 ++------------
> >arch/xtensa/include/asm/rwsem.h | 14 ++------------
> >2 files changed, 4 insertions(+), 24 deletions(-)
> 
> I think we can actually get rid of these files altogether.

And after double checking sparc is using the generic implementation
without any arch specific tweaks as well. So it can be dropped.

David, does the following look good to you or am I missing something?
I will drop "[PATCH 08/11] sparc, rwsem: provide __down_write_killable"
then.
---
>From 8a71514d2973f9e5c0330a23e0409d195e796b4c Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Wed, 6 Apr 2016 10:33:37 +0200
Subject: [PATCH] sparc, rwsem: drop superfluous arch specific implementation

sparc basically reuses generic implementation of rwsem so we can
reuse the code rather than duplicate it.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 arch/sparc/include/asm/Kbuild  |   1 +
 arch/sparc/include/asm/rwsem.h | 119 -----------------------------------------
 2 files changed, 1 insertion(+), 119 deletions(-)
 delete mode 100644 arch/sparc/include/asm/rwsem.h

diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild
index e928618838bc..6024c26c0585 100644
--- a/arch/sparc/include/asm/Kbuild
+++ b/arch/sparc/include/asm/Kbuild
@@ -16,6 +16,7 @@ generic-y += mm-arch-hooks.h
 generic-y += module.h
 generic-y += mutex.h
 generic-y += preempt.h
+generic-y += rwsem.h
 generic-y += serial.h
 generic-y += trace_clock.h
 generic-y += types.h
diff --git a/arch/sparc/include/asm/rwsem.h b/arch/sparc/include/asm/rwsem.h
deleted file mode 100644
index e5a0d575bc7f..000000000000
--- a/arch/sparc/include/asm/rwsem.h
+++ /dev/null
@@ -1,119 +0,0 @@
-/*
- * rwsem.h: R/W semaphores implemented using CAS
- *
- * Written by David S. Miller (davem@redhat.com), 2001.
- * Derived from asm-i386/rwsem.h
- */
-#ifndef _SPARC64_RWSEM_H
-#define _SPARC64_RWSEM_H
-
-#ifndef _LINUX_RWSEM_H
-#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
-#endif
-
-#ifdef __KERNEL__
-
-#define RWSEM_UNLOCKED_VALUE		0x00000000L
-#define RWSEM_ACTIVE_BIAS		0x00000001L
-#define RWSEM_ACTIVE_MASK		0xffffffffL
-#define RWSEM_WAITING_BIAS		(-RWSEM_ACTIVE_MASK-1)
-#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
-#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
-
-/*
- * lock for reading
- */
-static inline void __down_read(struct rw_semaphore *sem)
-{
-	if (unlikely(atomic64_inc_return((atomic64_t *)(&sem->count)) <= 0L))
-		rwsem_down_read_failed(sem);
-}
-
-static inline int __down_read_trylock(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	while ((tmp = sem->count) >= 0L) {
-		if (tmp == cmpxchg(&sem->count, tmp,
-				   tmp + RWSEM_ACTIVE_READ_BIAS)) {
-			return 1;
-		}
-	}
-	return 0;
-}
-
-/*
- * lock for writing
- */
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	tmp = atomic64_add_return(RWSEM_ACTIVE_WRITE_BIAS,
-				  (atomic64_t *)(&sem->count));
-	if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
-		rwsem_down_write_failed(sem);
-}
-
-static inline int __down_write_trylock(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
-		      RWSEM_ACTIVE_WRITE_BIAS);
-	return tmp == RWSEM_UNLOCKED_VALUE;
-}
-
-/*
- * unlock after reading
- */
-static inline void __up_read(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	tmp = atomic64_dec_return((atomic64_t *)(&sem->count));
-	if (unlikely(tmp < -1L && (tmp & RWSEM_ACTIVE_MASK) == 0L))
-		rwsem_wake(sem);
-}
-
-/*
- * unlock after writing
- */
-static inline void __up_write(struct rw_semaphore *sem)
-{
-	if (unlikely(atomic64_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
-					 (atomic64_t *)(&sem->count)) < 0L))
-		rwsem_wake(sem);
-}
-
-/*
- * implement atomic add functionality
- */
-static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
-{
-	atomic64_add(delta, (atomic64_t *)(&sem->count));
-}
-
-/*
- * downgrade write lock to read lock
- */
-static inline void __downgrade_write(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	tmp = atomic64_add_return(-RWSEM_WAITING_BIAS, (atomic64_t *)(&sem->count));
-	if (tmp < 0L)
-		rwsem_downgrade_wake(sem);
-}
-
-/*
- * implement exchange and add functionality
- */
-static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
-{
-	return atomic64_add_return(delta, (atomic64_t *)(&sem->count));
-}
-
-#endif /* __KERNEL__ */
-
-#endif /* _SPARC64_RWSEM_H */
-- 
2.8.0.rc3

-- 
Michal Hocko
SUSE Labs
