[PATCH] use smp_mb/wmb/rmb where possible

From: Anton Blanchard
Date: Fri Apr 29 2005 - 09:19:54 EST

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Hi,

Replace a number of memory barriers with smp_ variants. This means we
wont take the unnecessary hit on UP machines.

Signed-off-by: Anton Blanchard <anton@xxxxxxxxx>

Index: linux-2.6.12-rc2/fs/buffer.c
===================================================================
--- linux-2.6.12-rc2.orig/fs/buffer.c 2005-04-19 13:37:37.905690890 +1000
+++ linux-2.6.12-rc2/fs/buffer.c 2005-04-29 09:45:25.077846782 +1000
@@ -218,7 +218,7 @@
sb = get_super(bdev);
if (sb && !(sb->s_flags & MS_RDONLY)) {
sb->s_frozen = SB_FREEZE_WRITE;
- wmb();
+ smp_wmb();

sync_inodes_sb(sb, 0);
DQUOT_SYNC(sb);
@@ -235,7 +235,7 @@
sync_inodes_sb(sb, 1);

sb->s_frozen = SB_FREEZE_TRANS;
- wmb();
+ smp_wmb();

sync_blockdev(sb->s_bdev);

@@ -263,7 +263,7 @@
if (sb->s_op->unlockfs)
sb->s_op->unlockfs(sb);
sb->s_frozen = SB_UNFROZEN;
- wmb();
+ smp_wmb();
wake_up(&sb->s_wait_unfrozen);
drop_super(sb);
}
Index: linux-2.6.12-rc2/ipc/mqueue.c
===================================================================
--- linux-2.6.12-rc2.orig/ipc/mqueue.c 2004-10-29 07:03:22.000000000 +1000
+++ linux-2.6.12-rc2/ipc/mqueue.c 2005-04-29 09:45:25.081846475 +1000
@@ -767,7 +767,7 @@
list_del(&receiver->list);
receiver->state = STATE_PENDING;
wake_up_process(receiver->task);
- wmb();
+ smp_wmb();
receiver->state = STATE_READY;
}

@@ -786,7 +786,7 @@
list_del(&sender->list);
sender->state = STATE_PENDING;
wake_up_process(sender->task);
- wmb();
+ smp_wmb();
sender->state = STATE_READY;
}

Index: linux-2.6.12-rc2/kernel/kthread.c
===================================================================
--- linux-2.6.12-rc2.orig/kernel/kthread.c 2005-01-09 10:05:41.000000000 +1100
+++ linux-2.6.12-rc2/kernel/kthread.c 2005-04-29 09:45:25.082846399 +1000
@@ -174,7 +174,7 @@

/* Must init completion *before* thread sees kthread_stop_info.k */
init_completion(&kthread_stop_info.done);
- wmb();
+ smp_wmb();

/* Now set kthread_should_stop() to true, and wake it up. */
kthread_stop_info.k = k;
Index: linux-2.6.12-rc2/kernel/profile.c
===================================================================
--- linux-2.6.12-rc2.orig/kernel/profile.c 2005-04-29 09:45:17.095141481 +1000
+++ linux-2.6.12-rc2/kernel/profile.c 2005-04-29 09:45:25.084846246 +1000
@@ -528,7 +528,7 @@
return 0;
out_cleanup:
prof_on = 0;
- mb();
+ smp_mb();
on_each_cpu(profile_nop, NULL, 0, 1);
for_each_online_cpu(cpu) {
struct page *page;
Index: linux-2.6.12-rc2/kernel/ptrace.c
===================================================================
--- linux-2.6.12-rc2.orig/kernel/ptrace.c 2005-02-04 04:10:37.000000000 +1100
+++ linux-2.6.12-rc2/kernel/ptrace.c 2005-04-29 09:45:25.086846092 +1000
@@ -135,7 +135,7 @@
(current->gid != task->sgid) ||
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto bad;
- rmb();
+ smp_rmb();
if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
goto bad;
/* the same process cannot be attached many times */
Index: linux-2.6.12-rc2/kernel/stop_machine.c
===================================================================
--- linux-2.6.12-rc2.orig/kernel/stop_machine.c 2005-03-29 16:06:38.000000000 +1000
+++ linux-2.6.12-rc2/kernel/stop_machine.c 2005-04-29 09:45:25.088845939 +1000
@@ -33,7 +33,7 @@
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 @@
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 @@
}

/* 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 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();
Index: linux-2.6.12-rc2/kernel/sys.c
===================================================================
--- linux-2.6.12-rc2.orig/kernel/sys.c 2005-04-19 13:37:40.664011630 +1000
+++ linux-2.6.12-rc2/kernel/sys.c 2005-04-29 09:45:25.093845556 +1000
@@ -545,7 +545,7 @@
if (new_egid != old_egid)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
if (rgid != (gid_t) -1 ||
(egid != (gid_t) -1 && egid != old_rgid))
@@ -576,7 +576,7 @@
if(old_egid != gid)
{
current->mm->dumpable=0;
- wmb();
+ smp_wmb();
}
current->gid = current->egid = current->sgid = current->fsgid = gid;
}
@@ -585,7 +585,7 @@
if(old_egid != gid)
{
current->mm->dumpable=0;
- wmb();
+ smp_wmb();
}
current->egid = current->fsgid = gid;
}
@@ -616,7 +616,7 @@
if(dumpclear)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
current->uid = new_ruid;
return 0;
@@ -673,7 +673,7 @@
if (new_euid != old_euid)
{
current->mm->dumpable=0;
- wmb();
+ smp_wmb();
}
current->fsuid = current->euid = new_euid;
if (ruid != (uid_t) -1 ||
@@ -723,7 +723,7 @@
if (old_euid != uid)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
current->fsuid = current->euid = uid;
current->suid = new_suid;
@@ -768,7 +768,7 @@
if (euid != current->euid)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
current->euid = euid;
}
@@ -818,7 +818,7 @@
if (egid != current->egid)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
current->egid = egid;
}
@@ -865,7 +865,7 @@
if (uid != old_fsuid)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
current->fsuid = uid;
}
@@ -895,7 +895,7 @@
if (gid != old_fsgid)
{
current->mm->dumpable = 0;
- wmb();
+ smp_wmb();
}
current->fsgid = gid;
key_fsgid_changed(current);
Index: linux-2.6.12-rc2/kernel/timer.c
===================================================================
--- linux-2.6.12-rc2.orig/kernel/timer.c 2005-04-19 13:37:40.681010312 +1000
+++ linux-2.6.12-rc2/kernel/timer.c 2005-04-29 09:45:25.096845326 +1000
@@ -999,7 +999,7 @@
* Make sure we read the pid before re-reading the
* parent pointer:
*/
- rmb();
+ smp_rmb();
parent = me->group_leader->real_parent;
if (old != parent)
continue;
Index: linux-2.6.12-rc2/lib/rwsem-spinlock.c
===================================================================
--- linux-2.6.12-rc2.orig/lib/rwsem-spinlock.c 2005-03-10 06:08:38.000000000 +1100
+++ linux-2.6.12-rc2/lib/rwsem-spinlock.c 2005-04-29 09:45:25.098845173 +1000
@@ -76,7 +76,7 @@
list_del(&waiter->list);
tsk = waiter->task;
/* Don't touch waiter after ->task has been NULLed */
- mb();
+ smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
@@ -91,7 +91,7 @@

list_del(&waiter->list);
tsk = waiter->task;
- mb();
+ smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
@@ -123,7 +123,7 @@
list_del(&waiter->list);

tsk = waiter->task;
- mb();
+ smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
Index: linux-2.6.12-rc2/lib/rwsem.c
===================================================================
--- linux-2.6.12-rc2.orig/lib/rwsem.c 2005-03-10 06:08:38.000000000 +1100
+++ linux-2.6.12-rc2/lib/rwsem.c 2005-04-29 09:45:25.100845020 +1000
@@ -74,7 +74,7 @@
*/
list_del(&waiter->list);
tsk = waiter->task;
- mb();
+ smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
@@ -117,7 +117,7 @@
waiter = list_entry(next, struct rwsem_waiter, list);
next = waiter->list.next;
tsk = waiter->task;
- mb();
+ smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
Index: linux-2.6.12-rc2/mm/mempool.c
===================================================================
--- linux-2.6.12-rc2.orig/mm/mempool.c 2005-03-29 16:06:38.000000000 +1000
+++ linux-2.6.12-rc2/mm/mempool.c 2005-04-29 09:45:25.101844943 +1000
@@ -210,7 +210,7 @@
* If the pool is less than 50% full and we can perform effective
* page reclaim then try harder to allocate an element.
*/
- mb();
+ smp_mb();
if ((gfp_mask & __GFP_FS) && (gfp_mask != gfp_nowait) &&
(pool->curr_nr <= pool->min_nr/2)) {
element = pool->alloc(gfp_mask, pool->pool_data);
@@ -236,7 +236,7 @@
return NULL;

prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
- mb();
+ smp_mb();
if (!pool->curr_nr)
io_schedule();
finish_wait(&pool->wait, &wait);
@@ -257,7 +257,7 @@
{
unsigned long flags;

- mb();
+ smp_mb();
if (pool->curr_nr < pool->min_nr) {
spin_lock_irqsave(&pool->lock, flags);
if (pool->curr_nr < pool->min_nr) {
-
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Next message: Pedro Venda (SYSADM): "Re: ftp server crashes on heavy load: possible scheduler bug"
Previous message: Benjamin LaHaise: "Re: [RFC] unify semaphore implementations"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]