[PATCH] m32r: Revise __raw_read_trylock()

[Hirokazu Takata <takata@linux-m32r.org>]

Hi,

Matthew Wilcox pointed out that generic__raw_read_trylock() is
unfit for use.

Here is a patch to fix __raw_read_trylock() for m32r.
It is taken from the i386 implementation.

Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Cc: Matthew Wilcox <matthew@wil.cx>
---
 include/asm-m32r/spinlock.h |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/include/asm-m32r/spinlock.h b/include/asm-m32r/spinlock.h
index f94c1a6..78205f0 100644
--- a/include/asm-m32r/spinlock.h
+++ b/include/asm-m32r/spinlock.h
@@ -298,7 +298,15 @@ #endif	/* CONFIG_CHIP_M32700_TS1 */
 	);
 }
 
-#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
+static inline int __raw_read_trylock(raw_rwlock_t *lock)
+{
+	atomic_t *count = (atomic_t*)lock;
+	atomic_dec(count);
+	if (atomic_read(count) >= 0)
+		return 1;
+	atomic_inc(count);
+	return 0;
+}
 
 static inline int __raw_write_trylock(raw_rwlock_t *lock)
 {
-- 
Hirokazu Takata <takata@linux-m32r.org>
Linux/M32R Project:  http://www.linux-m32r.org/
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