From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Date: Thu, 20 Jan 2005 16:23:09 +0000
Subject: Re: [PATCH RFC] 'spinlock/rwlock fixes' V3 [1/1]
Message-Id: <20050120162309.GB14002@elte.hu>
List-Id: <linux-ia64.vger.kernel.org>
References: <20050116230922.7274f9a2.akpm@osdl.org> <20050117143301.GA10341@elte.hu> <20050118014752.GA14709@cse.unsw.EDU.AU> <16877.42598.336096.561224@wombat.chubb.wattle.id.au> <20050119080403.GB29037@elte.hu> <16878.9678.73202.771962@wombat.chubb.wattle.id.au> <20050119092013.GA2045@elte.hu> <16878.54402.344079.528038@cargo.ozlabs.ibm.com> <20050120023445.GA3475@taniwha.stupidest.org> <Pine.LNX.4.58.0501200812300.8178@ppc970.osdl.org>
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To: Linus Torvalds <torvalds@osdl.org>
Cc: Chris Wedgwood <cw@f00f.org>, Paul Mackerras <paulus@samba.org>, linux-kernel@vger.kernel.org, Peter Chubb <peterc@gelato.unsw.edu.au>, Tony Luck <tony.luck@intel.com>, Darren Williams <dsw@gelato.unsw.edu.au>, Andrew Morton <akpm@osdl.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Ia64 Linux <linux-ia64@vger.kernel.org>, Christoph Hellwig <hch@infradead.org>, William Lee Irwin III <wli@holomorphy.com>, Jesse Barnes <jbarnes@sgi.com>


* Linus Torvalds <torvalds@osdl.org> wrote:

> what the _heck_ is that "atomic_read((atomic_t *)&(x)->lock)", and why is 
> it not just a "(int)(x)->lock" instead?
> 
> So I think it would be much better as
> 
> 	#define read_can_lock(x) ((int)(x)->lock > 0)
> 
> which seems simple and straightforward.

right. Replace patch #4 with:

--- linux/include/asm-i386/spinlock.h.orig
+++ linux/include/asm-i386/spinlock.h
@@ -198,21 +198,33 @@ typedef struct {
 
 #define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT }
 
-#define rwlock_init(x)	do { *(x) = RW_LOCK_UNLOCKED; } while(0)
+static inline void rwlock_init(rwlock_t *rw)
+{
+	*rw = RW_LOCK_UNLOCKED;
+}
 
-#define rwlock_is_locked(x) ((x)->lock != RW_LOCK_BIAS)
+static inline int rwlock_is_locked(rwlock_t *rw)
+{
+	return rw->lock != RW_LOCK_BIAS;
+}
 
 /**
  * read_can_lock - would read_trylock() succeed?
  * @lock: the rwlock in question.
  */
-#define read_can_lock(x) (atomic_read((atomic_t *)&(x)->lock) > 0)
+static inline int read_can_lock(rwlock_t *rw)
+{
+	return rw->lock > 0;
+}
 
 /**
  * write_can_lock - would write_trylock() succeed?
  * @lock: the rwlock in question.
  */
-#define write_can_lock(x) ((x)->lock = RW_LOCK_BIAS)
+static inline int write_can_lock(rwlock_t *rw)
+{
+	return rw->lock = RW_LOCK_BIAS;
+}
 
 /*
  * On x86, we implement read-write locks as a 32-bit counter
@@ -241,8 +253,16 @@ static inline void _raw_write_lock(rwloc
 	__build_write_lock(rw, "__write_lock_failed");
 }
 
-#define _raw_read_unlock(rw)		asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
-#define _raw_write_unlock(rw)	asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
+static inline void _raw_read_unlock(rwlock_t *rw)
+{
+	asm volatile("lock ; incl %0" :"=m" (rw->lock) : : "memory");
+}
+
+static inline void _raw_write_unlock(rwlock_t *rw)
+{
+	asm volatile("lock ; addl $" RW_LOCK_BIAS_STR
+				",%0":"=m" (rw->lock) : : "memory");
+}
 
 static inline int _raw_read_trylock(rwlock_t *lock)
 {