From d59dd4620fb8d6422555a9e2b82a707718e68327 Mon Sep 17 00:00:00 2001 From: "akpm@osdl.org" Date: Sun, 1 May 2005 08:58:47 -0700 Subject: [PATCH] use smp_mb/wmb/rmb where possible Replace a number of memory barriers with smp_ variants. This means we won't take the unnecessary hit on UP machines. Signed-off-by: Anton Blanchard Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/stop_machine.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index c39ed70af174..6116b25aa7cf 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -33,7 +33,7 @@ static int stopmachine(void *cpu) set_cpus_allowed(current, cpumask_of_cpu((int)(long)cpu)); /* Ack: we are alive */ - mb(); /* Theoretically the ack = 0 might not be on this CPU yet. */ + smp_mb(); /* Theoretically the ack = 0 might not be on this CPU yet. */ atomic_inc(&stopmachine_thread_ack); /* Simple state machine */ @@ -43,14 +43,14 @@ static int stopmachine(void *cpu) local_irq_disable(); irqs_disabled = 1; /* Ack: irqs disabled. */ - mb(); /* Must read state first. */ + smp_mb(); /* Must read state first. */ atomic_inc(&stopmachine_thread_ack); } else if (stopmachine_state == STOPMACHINE_PREPARE && !prepared) { /* Everyone is in place, hold CPU. */ preempt_disable(); prepared = 1; - mb(); /* Must read state first. */ + smp_mb(); /* Must read state first. */ atomic_inc(&stopmachine_thread_ack); } /* Yield in first stage: migration threads need to @@ -62,7 +62,7 @@ static int stopmachine(void *cpu) } /* Ack: we are exiting. */ - mb(); /* Must read state first. */ + smp_mb(); /* Must read state first. */ atomic_inc(&stopmachine_thread_ack); if (irqs_disabled) @@ -77,7 +77,7 @@ static int stopmachine(void *cpu) static void stopmachine_set_state(enum stopmachine_state state) { atomic_set(&stopmachine_thread_ack, 0); - wmb(); + smp_wmb(); stopmachine_state = state; while (atomic_read(&stopmachine_thread_ack) != stopmachine_num_threads) cpu_relax(); -- cgit v1.2.3-59-g8ed1b