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Date: Mon, 17 Mar 2008 12:37:19 -0400
From: "Alan D. Brunelle" <Alan.Brunelle@...com>
To: linux-kernel@...r.kernel.org
Cc: Jens Axboe <jens.axboe@...cle.com>, npiggin@...e.de, dgc@....com
Subject: [Patch (block.git) 2/2] Ensure single IPI generation for SMP call
single
Signed-off-by: Alan D. Brunelle <alan.brunelle@...com>
---
arch/ia64/kernel/smp.c | 8 ++++++--
arch/x86/kernel/smp_32.c | 8 ++++++--
arch/x86/kernel/smp_64.c | 8 ++++++--
include/linux/smp.h | 1 +
kernel/smp.c | 34 ++++++++++++++++++++--------------
5 files changed, 39 insertions(+), 20 deletions(-)
diff --git a/arch/ia64/kernel/smp.c b/arch/ia64/kernel/smp.c
index 04ba9f8..52225bb 100644
--- a/arch/ia64/kernel/smp.c
+++ b/arch/ia64/kernel/smp.c
@@ -364,7 +364,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
{
struct call_single_queue *dst;
unsigned long flags;
- int ipi, wait_done = data->flags & CSD_FLAG_WAIT;
+ int ipi = 0;
+ int wait_done = data->flags & CSD_FLAG_WAIT;
/* Can deadlock when called with interrupts disabled */
WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
@@ -373,8 +374,11 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
dst = &per_cpu(call_single_queue, cpu);
spin_lock_irqsave(&dst->lock, flags);
- ipi = list_empty(&dst->list);
list_add_tail(&data->list, &dst->list);
+ if (!dst->activated) {
+ dst->activated = 1;
+ ipi = 1;
+ }
spin_unlock_irqrestore(&dst->lock, flags);
if (ipi)
diff --git a/arch/x86/kernel/smp_32.c b/arch/x86/kernel/smp_32.c
index be0f6cb..d166f13 100644
--- a/arch/x86/kernel/smp_32.c
+++ b/arch/x86/kernel/smp_32.c
@@ -629,7 +629,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
cpumask_t mask = cpumask_of_cpu(cpu);
struct call_single_queue *dst;
unsigned long flags;
- int ipi, wait_done = data->flags & CSD_FLAG_WAIT;
+ int ipi = 0;
+ int wait_done = data->flags & CSD_FLAG_WAIT;
/* Can deadlock when called with interrupts disabled */
WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
@@ -638,8 +639,11 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
dst = &per_cpu(call_single_queue, cpu);
spin_lock_irqsave(&dst->lock, flags);
- ipi = list_empty(&dst->list);
list_add_tail(&data->list, &dst->list);
+ if (!dst->activated) {
+ dst->activated = 1;
+ ipi = 1;
+ }
spin_unlock_irqrestore(&dst->lock, flags);
if (ipi)
diff --git a/arch/x86/kernel/smp_64.c b/arch/x86/kernel/smp_64.c
index 5bef2a6..fbfcdce 100644
--- a/arch/x86/kernel/smp_64.c
+++ b/arch/x86/kernel/smp_64.c
@@ -449,7 +449,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
cpumask_t mask = cpumask_of_cpu(cpu);
struct call_single_queue *dst;
unsigned long flags;
- int ipi, wait_done = data->flags & CSD_FLAG_WAIT;
+ int ipi = 0;
+ int wait_done = data->flags & CSD_FLAG_WAIT;
/* Can deadlock when called with interrupts disabled */
WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
@@ -458,8 +459,11 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
dst = &per_cpu(call_single_queue, cpu);
spin_lock_irqsave(&dst->lock, flags);
- ipi = list_empty(&dst->list);
list_add_tail(&data->list, &dst->list);
+ if (!dst->activated) {
+ dst->activated = 1;
+ ipi = 1;
+ }
spin_unlock_irqrestore(&dst->lock, flags);
if (ipi)
diff --git a/include/linux/smp.h b/include/linux/smp.h
index c471d77..1e96f03 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -65,6 +65,7 @@ extern void smp_cpus_done(unsigned int max_cpus);
struct call_single_queue {
spinlock_t lock;
struct list_head list;
+ int activated;
};
/*
diff --git a/kernel/smp.c b/kernel/smp.c
index 7232e1c..f7ec401 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -23,28 +23,34 @@ void __cpuinit generic_init_call_single_data(void)
void generic_smp_call_function_single_interrupt(void)
{
- struct call_single_queue *q;
unsigned long flags;
LIST_HEAD(list);
+ struct call_single_queue *q = &__get_cpu_var(call_single_queue);
- q = &__get_cpu_var(call_single_queue);
spin_lock_irqsave(&q->lock, flags);
- list_replace_init(&q->list, &list);
- spin_unlock_irqrestore(&q->lock, flags);
+ while (!list_empty(&q->list)) {
+ list_replace_init(&q->list, &list);
+ spin_unlock_irqrestore(&q->lock, flags);
- while (!list_empty(&list)) {
- struct call_single_data *data;
+ do {
+ struct call_single_data *data;
- data = list_entry(list.next, struct call_single_data, list);
- list_del(&data->list);
+ data = list_entry(list.next, struct call_single_data,
+ list);
+ list_del(&data->list);
- data->func(data->info);
- if (data->flags & CSD_FLAG_WAIT) {
- smp_wmb();
- data->flags = 0;
- } else if (data->flags & CSD_FLAG_ALLOC)
- kfree(data);
+ data->func(data->info);
+ if (data->flags & CSD_FLAG_WAIT) {
+ smp_wmb();
+ data->flags = 0;
+ } else if (data->flags & CSD_FLAG_ALLOC)
+ kfree(data);
+ } while (!list_empty(&list));
+
+ spin_lock_irqsave(&q->lock, flags);
}
+ q->activated = 0;
+ spin_unlock_irqrestore(&q->lock, flags);
}
int generic_smp_call_function_single(int cpu, void (*func) (void *info),
--
1.5.2.5
--
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