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

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
......@@ -119,22 +119,8 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned long tmp;
u32 slock;
smp_mb();
__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");
lock->tickets.owner++;
dsb_sev();
}
......
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