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-rw-r--r--block/blk-softirq.c2
-rw-r--r--include/linux/smp.h3
-rw-r--r--kernel/sched.c2
-rw-r--r--kernel/smp.c90
-rw-r--r--kernel/softirq.c2
5 files changed, 28 insertions, 71 deletions
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index ce0efc6..ee9c216 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -64,7 +64,7 @@ static int raise_blk_irq(int cpu, struct request *rq)
data->info = rq;
data->flags = 0;
- __smp_call_function_single(cpu, data);
+ __smp_call_function_single(cpu, data, 0);
return 0;
}
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 715196b..00866d7 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -82,7 +82,8 @@ smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info,
return 0;
}
-void __smp_call_function_single(int cpuid, struct call_single_data *data);
+void __smp_call_function_single(int cpuid, struct call_single_data *data,
+ int wait);
/*
* Generic and arch helpers
diff --git a/kernel/sched.c b/kernel/sched.c
index 410eec4..d4c2749 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1093,7 +1093,7 @@ static void hrtick_start(struct rq *rq, u64 delay)
if (rq == this_rq()) {
hrtimer_restart(timer);
} else if (!rq->hrtick_csd_pending) {
- __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd);
+ __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
rq->hrtick_csd_pending = 1;
}
}
diff --git a/kernel/smp.c b/kernel/smp.c
index 7a0ce25..f530825 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -23,8 +23,7 @@ static struct {
};
enum {
- CSD_FLAG_WAIT = 0x01,
- CSD_FLAG_LOCK = 0x02,
+ CSD_FLAG_LOCK = 0x01,
};
struct call_function_data {
@@ -95,41 +94,21 @@ static int __cpuinit init_call_single_data(void)
early_initcall(init_call_single_data);
/*
- * csd_wait/csd_complete are used for synchronous ipi calls
- */
-static void csd_wait_prepare(struct call_single_data *data)
-{
- data->flags |= CSD_FLAG_WAIT;
-}
-
-static void csd_complete(struct call_single_data *data)
-{
- if (data->flags & CSD_FLAG_WAIT) {
- /*
- * ensure we're all done before saying we are
- */
- smp_mb();
- data->flags &= ~CSD_FLAG_WAIT;
- }
-}
-
-static void csd_wait(struct call_single_data *data)
-{
- while (data->flags & CSD_FLAG_WAIT)
- cpu_relax();
-}
-
-/*
* csd_lock/csd_unlock used to serialize access to per-cpu csd resources
*
* For non-synchronous ipi calls the csd can still be in use by the previous
* function call. For multi-cpu calls its even more interesting as we'll have
* to ensure no other cpu is observing our csd.
*/
-static void csd_lock(struct call_single_data *data)
+static void csd_lock_wait(struct call_single_data *data)
{
while (data->flags & CSD_FLAG_LOCK)
cpu_relax();
+}
+
+static void csd_lock(struct call_single_data *data)
+{
+ csd_lock_wait(data);
data->flags = CSD_FLAG_LOCK;
/*
@@ -155,11 +134,12 @@ static void csd_unlock(struct call_single_data *data)
* Insert a previously allocated call_single_data element for execution
* on the given CPU. data must already have ->func, ->info, and ->flags set.
*/
-static void generic_exec_single(int cpu, struct call_single_data *data)
+static
+void generic_exec_single(int cpu, struct call_single_data *data, int wait)
{
struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
- int wait = data->flags & CSD_FLAG_WAIT, ipi;
unsigned long flags;
+ int ipi;
spin_lock_irqsave(&dst->lock, flags);
ipi = list_empty(&dst->list);
@@ -182,7 +162,7 @@ static void generic_exec_single(int cpu, struct call_single_data *data)
arch_send_call_function_single_ipi(cpu);
if (wait)
- csd_wait(data);
+ csd_lock_wait(data);
}
/*
@@ -232,7 +212,6 @@ void generic_smp_call_function_interrupt(void)
if (refs)
continue;
- csd_complete(&data->csd);
csd_unlock(&data->csd);
}
@@ -270,9 +249,6 @@ void generic_smp_call_function_single_interrupt(void)
data->func(data->info);
- if (data_flags & CSD_FLAG_WAIT)
- csd_complete(data);
-
/*
* Unlocked CSDs are valid through generic_exec_single()
*/
@@ -313,36 +289,16 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
func(info);
local_irq_restore(flags);
} else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
- struct call_single_data *data;
+ struct call_single_data *data = &d;
- if (!wait) {
- /*
- * We are calling a function on a single CPU
- * and we are not going to wait for it to finish.
- * We use a per cpu data to pass the information to
- * that CPU. Since all callers of this code will
- * use the same data, we must synchronize the
- * callers to prevent a new caller from corrupting
- * the data before the callee can access it.
- *
- * The CSD_FLAG_LOCK is used to let us know when
- * the IPI handler is done with the data.
- * The first caller will set it, and the callee
- * will clear it. The next caller must wait for
- * it to clear before we set it again. This
- * will make sure the callee is done with the
- * data before a new caller will use it.
- */
+ if (!wait)
data = &__get_cpu_var(csd_data);
- csd_lock(data);
- } else {
- data = &d;
- csd_wait_prepare(data);
- }
+
+ csd_lock(data);
data->func = func;
data->info = info;
- generic_exec_single(cpu, data);
+ generic_exec_single(cpu, data, wait);
} else {
err = -ENXIO; /* CPU not online */
}
@@ -362,12 +318,15 @@ EXPORT_SYMBOL(smp_call_function_single);
* instance.
*
*/
-void __smp_call_function_single(int cpu, struct call_single_data *data)
+void __smp_call_function_single(int cpu, struct call_single_data *data,
+ int wait)
{
+ csd_lock(data);
+
/* Can deadlock when called with interrupts disabled */
- WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
+ WARN_ON(wait && irqs_disabled());
- generic_exec_single(cpu, data);
+ generic_exec_single(cpu, data, wait);
}
/* FIXME: Shim for archs using old arch_send_call_function_ipi API. */
@@ -425,9 +384,6 @@ void smp_call_function_many(const struct cpumask *mask,
csd_lock(&data->csd);
spin_lock_irqsave(&data->lock, flags);
- if (wait)
- csd_wait_prepare(&data->csd);
-
data->csd.func = func;
data->csd.info = info;
cpumask_and(data->cpumask, mask, cpu_online_mask);
@@ -456,7 +412,7 @@ void smp_call_function_many(const struct cpumask *mask,
/* optionally wait for the CPUs to complete */
if (wait)
- csd_wait(&data->csd);
+ csd_lock_wait(&data->csd);
}
EXPORT_SYMBOL(smp_call_function_many);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index bdbe9de..48c3d5d 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -496,7 +496,7 @@ static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softir
cp->flags = 0;
cp->priv = softirq;
- __smp_call_function_single(cpu, cp);
+ __smp_call_function_single(cpu, cp, 0);
return 0;
}
return 1;