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Commit 8e34703b authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[ARM] Fix ARM __raw_read_trylock() implementation 



Matthew Wilcox pointed out that the generic implementation
of this is unfit for use.  Here's an ARM optimised version
instead.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 0355b3e0

include/asm-arm/spinlock.h

+15 −1
Original line number Diff line number Diff line
@@ -199,7 +199,21 @@ static inline void __raw_read_unlock(raw_rwlock_t *rw) 
	: "cc");

}



#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)

static inline int __raw_read_trylock(raw_rwlock_t *rw)

{

	unsigned long tmp tmp2 = 1;



	__asm__ __volatile__(

"1:	ldrex	%0, [%2]\n"

"	adds	%0, %0, #1\n"

"	strexpl	%1, %0, [%2]\n"

	: "=&r" (tmp), "+r" (tmp2)

	: "r" (&rw->lock)

	: "cc");



	smp_mb();

	return tmp2 == 0;

}



/* read_can_lock - would read_trylock() succeed? */

#define __raw_read_can_lock(x)		((x)->lock < 0x80000000)