Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 20e260b6 authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

ARM: 7632/1: spinlock: avoid exclusive accesses on unlock() path 



When unlocking a spinlock, all we need to do is increment the owner
field of the lock. Since only one CPU can be performing an unlock()
operation for a given lock, this doesn't need to be exclusive.

This patch simplifies arch_spin_unlock to use non-exclusive accesses
when updating the owner field of the lock.

Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 0a301110

arch/arm/include/asm/spinlock.h

+1 −15
Original line number Original line Diff line number Diff line
@@ -119,22 +119,8 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) 




static inline void arch_spin_unlock(arch_spinlock_t *lock)

static inline void arch_spin_unlock(arch_spinlock_t *lock)

{

{

	unsigned long tmp;

	u32 slock;



	smp_mb();

	smp_mb();



	lock->tickets.owner++;

	__asm__ __volatile__(

"	mov	%1, #1\n"

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

"	uadd16	%0, %0, %1\n"

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

"	teq	%1, #0\n"

"	bne	1b"

	: "=&r" (slock), "=&r" (tmp)

	: "r" (&lock->slock)

	: "cc");



	dsb_sev();

	dsb_sev();

}

}