TononixOS/ubports_kernel_google_msm
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[PATCH] use smp_mb/wmb/rmb where possible

Browse Source 
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 <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
akpm@osdl.org
2005-05-01 08:58:47 -07:00
committed by Linus Torvalds
parent 0d8d4d42f2
commit d59dd4620f
11 changed files with 31 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/stop_machine.c
View File

@@ -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();