From bf67fd3142dc605ded9b5e063e35b47c2bb21cb1 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 9 Jul 2014 19:31:28 +0100 Subject: [PATCH] ARM: 8098/1: mcs lock: implement wfe-based polling for MCS locking This patch introduces a wfe-based polling loop for spinning on contended MCS locks and waking up corresponding waiters when the lock is released. Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/include/asm/mcs_spinlock.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 arch/arm/include/asm/mcs_spinlock.h diff --git a/arch/arm/include/asm/mcs_spinlock.h b/arch/arm/include/asm/mcs_spinlock.h new file mode 100644 index 00000000000..f652ad65840 --- /dev/null +++ b/arch/arm/include/asm/mcs_spinlock.h @@ -0,0 +1,23 @@ +#ifndef __ASM_MCS_LOCK_H +#define __ASM_MCS_LOCK_H + +#ifdef CONFIG_SMP +#include + +/* MCS spin-locking. */ +#define arch_mcs_spin_lock_contended(lock) \ +do { \ + /* Ensure prior stores are observed before we enter wfe. */ \ + smp_mb(); \ + while (!(smp_load_acquire(lock))) \ + wfe(); \ +} while (0) \ + +#define arch_mcs_spin_unlock_contended(lock) \ +do { \ + smp_store_release(lock, 1); \ + dsb_sev(); \ +} while (0) + +#endif /* CONFIG_SMP */ +#endif /* __ASM_MCS_LOCK_H */ -- 2.46.0