enum {
CSD_FLAG_WAIT = 0x01,
CSD_FLAG_ALLOC = 0x02,
+ CSD_FLAG_LOCK = 0x04,
};
struct call_function_data {
struct call_single_data csd;
spinlock_t lock;
unsigned int refs;
- cpumask_t cpumask;
struct rcu_head rcu_head;
+ unsigned long cpumask_bits[];
};
struct call_single_queue {
spinlock_t lock;
};
-void __cpuinit init_call_single_data(void)
+static int __cpuinit init_call_single_data(void)
{
int i;
spin_lock_init(&q->lock);
INIT_LIST_HEAD(&q->list);
}
+ return 0;
}
+early_initcall(init_call_single_data);
static void csd_flag_wait(struct call_single_data *data)
{
/* Wait for response */
do {
- /*
- * We need to see the flags store in the IPI handler
- */
- smp_mb();
if (!(data->flags & CSD_FLAG_WAIT))
break;
cpu_relax();
list_add_tail(&data->list, &dst->list);
spin_unlock_irqrestore(&dst->lock, flags);
+ /*
+ * Make the list addition visible before sending the ipi.
+ */
+ smp_mb();
+
if (ipi)
arch_send_call_function_single_ipi(cpu);
list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
int refs;
- if (!cpu_isset(cpu, data->cpumask))
+ if (!cpumask_test_cpu(cpu, to_cpumask(data->cpumask_bits)))
continue;
data->csd.func(data->csd.info);
spin_lock(&data->lock);
- cpu_clear(cpu, data->cpumask);
+ cpumask_clear_cpu(cpu, to_cpumask(data->cpumask_bits));
WARN_ON(data->refs == 0);
data->refs--;
refs = data->refs;
*/
smp_wmb();
data->csd.flags &= ~CSD_FLAG_WAIT;
- } else
+ }
+ if (data->csd.flags & CSD_FLAG_ALLOC)
call_rcu(&data->rcu_head, rcu_free_call_data);
}
rcu_read_unlock();
* Need to see other stores to list head for checking whether
* list is empty without holding q->lock
*/
- smp_mb();
+ smp_read_barrier_depends();
while (!list_empty(&q->list)) {
unsigned int data_flags;
if (data_flags & CSD_FLAG_WAIT) {
smp_wmb();
data->flags &= ~CSD_FLAG_WAIT;
+ } else if (data_flags & CSD_FLAG_LOCK) {
+ smp_wmb();
+ data->flags &= ~CSD_FLAG_LOCK;
} else if (data_flags & CSD_FLAG_ALLOC)
kfree(data);
}
/*
* See comment on outer loop
*/
- smp_mb();
+ smp_read_barrier_depends();
}
}
+static DEFINE_PER_CPU(struct call_single_data, csd_data);
+
/*
* smp_call_function_single - Run a function on a specific CPU
* @func: The function to run. This must be fast and non-blocking.
{
struct call_single_data d;
unsigned long flags;
- /* prevent preemption and reschedule on another processor */
+ /* prevent preemption and reschedule on another processor,
+ as well as CPU removal */
int me = get_cpu();
+ int err = 0;
/* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled());
local_irq_save(flags);
func(info);
local_irq_restore(flags);
- } else {
- struct call_single_data *data = NULL;
+ } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
+ struct call_single_data *data;
if (!wait) {
+ /*
+ * We are calling a function on a single CPU
+ * and we are not going to wait for it to finish.
+ * We first try to allocate the data, but if we
+ * fail, we fall back to 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.
+ */
data = kmalloc(sizeof(*data), GFP_ATOMIC);
if (data)
data->flags = CSD_FLAG_ALLOC;
- }
- if (!data) {
+ else {
+ data = &per_cpu(csd_data, me);
+ while (data->flags & CSD_FLAG_LOCK)
+ cpu_relax();
+ data->flags = CSD_FLAG_LOCK;
+ }
+ } else {
data = &d;
data->flags = CSD_FLAG_WAIT;
}
data->func = func;
data->info = info;
generic_exec_single(cpu, data);
+ } else {
+ err = -ENXIO; /* CPU not online */
}
put_cpu();
- return 0;
+ return err;
}
EXPORT_SYMBOL(smp_call_function_single);
generic_exec_single(cpu, data);
}
+/* FIXME: Shim for archs using old arch_send_call_function_ipi API. */
+#ifndef arch_send_call_function_ipi_mask
+#define arch_send_call_function_ipi_mask(maskp) \
+ arch_send_call_function_ipi(*(maskp))
+#endif
+
/**
- * smp_call_function_mask(): Run a function on a set of other CPUs.
- * @mask: The set of cpus to run on.
+ * smp_call_function_many(): Run a function on a set of other CPUs.
+ * @mask: The set of cpus to run on (only runs on online subset).
* @func: The function to run. This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to the function.
* @wait: If true, wait (atomically) until function has completed on other CPUs.
*
- * Returns 0 on success, else a negative status code.
- *
* If @wait is true, then returns once @func has returned. Note that @wait
* will be implicitly turned on in case of allocation failures, since
* we fall back to on-stack allocation.
* hardware interrupt handler or from a bottom half handler. Preemption
* must be disabled when calling this function.
*/
-int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info,
- int wait)
+void smp_call_function_many(const struct cpumask *mask,
+ void (*func)(void *), void *info,
+ bool wait)
{
- struct call_function_data d;
- struct call_function_data *data = NULL;
- cpumask_t allbutself;
+ struct call_function_data *data;
unsigned long flags;
- int cpu, num_cpus;
+ int cpu, next_cpu;
/* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled());
- cpu = smp_processor_id();
- allbutself = cpu_online_map;
- cpu_clear(cpu, allbutself);
- cpus_and(mask, mask, allbutself);
- num_cpus = cpus_weight(mask);
-
- /*
- * If zero CPUs, return. If just a single CPU, turn this request
- * into a targetted single call instead since it's faster.
- */
- if (!num_cpus)
- return 0;
- else if (num_cpus == 1) {
- cpu = first_cpu(mask);
- return smp_call_function_single(cpu, func, info, wait);
+ /* So, what's a CPU they want? Ignoring this one. */
+ cpu = cpumask_first_and(mask, cpu_online_mask);
+ if (cpu == smp_processor_id())
+ cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+ /* No online cpus? We're done. */
+ if (cpu >= nr_cpu_ids)
+ return;
+
+ /* Do we have another CPU which isn't us? */
+ next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+ if (next_cpu == smp_processor_id())
+ next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
+
+ /* Fastpath: do that cpu by itself. */
+ if (next_cpu >= nr_cpu_ids) {
+ smp_call_function_single(cpu, func, info, wait);
+ return;
}
- if (!wait) {
- data = kmalloc(sizeof(*data), GFP_ATOMIC);
- if (data)
- data->csd.flags = CSD_FLAG_ALLOC;
- }
- if (!data) {
- data = &d;
- data->csd.flags = CSD_FLAG_WAIT;
+ data = kmalloc(sizeof(*data) + cpumask_size(), GFP_ATOMIC);
+ if (unlikely(!data)) {
+ /* Slow path. */
+ for_each_online_cpu(cpu) {
+ if (cpu == smp_processor_id())
+ continue;
+ if (cpumask_test_cpu(cpu, mask))
+ smp_call_function_single(cpu, func, info, wait);
+ }
+ return;
}
spin_lock_init(&data->lock);
+ data->csd.flags = CSD_FLAG_ALLOC;
+ if (wait)
+ data->csd.flags |= CSD_FLAG_WAIT;
data->csd.func = func;
data->csd.info = info;
- data->refs = num_cpus;
- data->cpumask = mask;
+ cpumask_and(to_cpumask(data->cpumask_bits), mask, cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), to_cpumask(data->cpumask_bits));
+ data->refs = cpumask_weight(to_cpumask(data->cpumask_bits));
spin_lock_irqsave(&call_function_lock, flags);
list_add_tail_rcu(&data->csd.list, &call_function_queue);
spin_unlock_irqrestore(&call_function_lock, flags);
+ /*
+ * Make the list addition visible before sending the ipi.
+ */
+ smp_mb();
+
/* Send a message to all CPUs in the map */
- arch_send_call_function_ipi(mask);
+ arch_send_call_function_ipi_mask(to_cpumask(data->cpumask_bits));
/* optionally wait for the CPUs to complete */
if (wait)
csd_flag_wait(&data->csd);
-
- return 0;
}
-EXPORT_SYMBOL(smp_call_function_mask);
+EXPORT_SYMBOL(smp_call_function_many);
/**
* smp_call_function(): Run a function on all other CPUs.
* @info: An arbitrary pointer to pass to the function.
* @wait: If true, wait (atomically) until function has completed on other CPUs.
*
- * Returns 0 on success, else a negative status code.
+ * Returns 0.
*
* If @wait is true, then returns once @func has returned; otherwise
* it returns just before the target cpu calls @func. In case of allocation
*/
int smp_call_function(void (*func)(void *), void *info, int wait)
{
- int ret;
-
preempt_disable();
- ret = smp_call_function_mask(cpu_online_map, func, info, wait);
+ smp_call_function_many(cpu_online_mask, func, info, wait);
preempt_enable();
- return ret;
+ return 0;
}
EXPORT_SYMBOL(smp_call_function);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff