#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/smp.h>
+#include <linux/cpu.h>
static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
-static LIST_HEAD(call_function_queue);
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);
+
+static struct {
+ struct list_head queue;
+ spinlock_t lock;
+} call_function __cacheline_aligned_in_smp = {
+ .queue = LIST_HEAD_INIT(call_function.queue),
+ .lock = __SPIN_LOCK_UNLOCKED(call_function.lock),
+};
enum {
CSD_FLAG_WAIT = 0x01,
- CSD_FLAG_ALLOC = 0x02,
- CSD_FLAG_LOCK = 0x04,
+ CSD_FLAG_LOCK = 0x02,
};
struct call_function_data {
struct call_single_data csd;
spinlock_t lock;
unsigned int refs;
- struct rcu_head rcu_head;
- unsigned long cpumask_bits[];
+ cpumask_var_t cpumask;
};
struct call_single_queue {
spinlock_t lock;
};
+static DEFINE_PER_CPU(struct call_function_data, cfd_data) = {
+ .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
+};
+
+static int
+hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+ long cpu = (long)hcpu;
+ struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ if (!alloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
+ cpu_to_node(cpu)))
+ return NOTIFY_BAD;
+ break;
+
+#ifdef CONFIG_CPU_HOTPLUG
+ case CPU_UP_CANCELED:
+ case CPU_UP_CANCELED_FROZEN:
+
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ free_cpumask_var(cfd->cpumask);
+ break;
+#endif
+ };
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
+ .notifier_call = hotplug_cfd,
+};
+
static int __cpuinit init_call_single_data(void)
{
+ void *cpu = (void *)(long)smp_processor_id();
int i;
for_each_possible_cpu(i) {
spin_lock_init(&q->lock);
INIT_LIST_HEAD(&q->list);
}
+
+ hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
+ register_cpu_notifier(&hotplug_cfd_notifier);
+
return 0;
}
early_initcall(init_call_single_data);
-static void csd_flag_wait(struct call_single_data *data)
+/*
+ * csd_wait/csd_complete are used for synchronous ipi calls
+ */
+static void csd_wait_prepare(struct call_single_data *data)
{
- /* Wait for response */
- do {
- if (!(data->flags & CSD_FLAG_WAIT))
- break;
+ 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();
- } while (1);
+}
+
+/*
+ * 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)
+{
+ while (data->flags & CSD_FLAG_LOCK)
+ cpu_relax();
+ data->flags = CSD_FLAG_LOCK;
+
+ /*
+ * prevent CPU from reordering the above assignment to ->flags
+ * with any subsequent assignments to other fields of the
+ * specified call_single_data structure.
+ */
+
+ smp_mb();
+}
+
+static void csd_unlock(struct call_single_data *data)
+{
+ WARN_ON(!(data->flags & CSD_FLAG_LOCK));
+ /*
+ * ensure we're all done before releasing data
+ */
+ smp_mb();
+ data->flags &= ~CSD_FLAG_LOCK;
}
/*
arch_send_call_function_single_ipi(cpu);
if (wait)
- csd_flag_wait(data);
-}
-
-static void rcu_free_call_data(struct rcu_head *head)
-{
- struct call_function_data *data;
-
- data = container_of(head, struct call_function_data, rcu_head);
-
- kfree(data);
+ csd_wait(data);
}
/*
* It's ok to use list_for_each_rcu() here even though we may delete
* 'pos', since list_del_rcu() doesn't clear ->next
*/
- rcu_read_lock();
- list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
+ list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
int refs;
- if (!cpumask_test_cpu(cpu, to_cpumask(data->cpumask_bits)))
+ spin_lock(&data->lock);
+ if (!cpumask_test_cpu(cpu, data->cpumask)) {
+ spin_unlock(&data->lock);
continue;
+ }
+ cpumask_clear_cpu(cpu, data->cpumask);
+ spin_unlock(&data->lock);
data->csd.func(data->csd.info);
spin_lock(&data->lock);
- cpumask_clear_cpu(cpu, to_cpumask(data->cpumask_bits));
WARN_ON(data->refs == 0);
- data->refs--;
- refs = data->refs;
+ refs = --data->refs;
+ if (!refs) {
+ spin_lock(&call_function.lock);
+ list_del_rcu(&data->csd.list);
+ spin_unlock(&call_function.lock);
+ }
spin_unlock(&data->lock);
if (refs)
continue;
- spin_lock(&call_function_lock);
- list_del_rcu(&data->csd.list);
- spin_unlock(&call_function_lock);
-
- if (data->csd.flags & CSD_FLAG_WAIT) {
- /*
- * serialize stores to data with the flag clear
- * and wakeup
- */
- smp_wmb();
- data->csd.flags &= ~CSD_FLAG_WAIT;
- }
- if (data->csd.flags & CSD_FLAG_ALLOC)
- call_rcu(&data->rcu_head, rcu_free_call_data);
+ csd_complete(&data->csd);
+ csd_unlock(&data->csd);
}
- rcu_read_unlock();
put_cpu();
}
data->func(data->info);
- 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);
+ if (data_flags & CSD_FLAG_WAIT)
+ csd_complete(data);
+
+ /*
+ * Unlocked CSDs are valid through generic_exec_single()
+ */
+ if (data_flags & CSD_FLAG_LOCK)
+ csd_unlock(data);
}
}
int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
int wait)
{
- struct call_single_data d;
+ struct call_single_data d = {
+ .flags = 0,
+ };
unsigned long flags;
/* prevent preemption and reschedule on another processor,
as well as CPU removal */
/*
* 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.
+ * 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.
* 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;
- else {
- data = &per_cpu(csd_data, me);
- while (data->flags & CSD_FLAG_LOCK)
- cpu_relax();
- data->flags = CSD_FLAG_LOCK;
- }
+ data = &__get_cpu_var(csd_data);
+ csd_lock(data);
} else {
data = &d;
- data->flags = CSD_FLAG_WAIT;
+ csd_wait_prepare(data);
}
data->func = func;
{
struct call_function_data *data;
unsigned long flags;
- int cpu, next_cpu;
+ int cpu, next_cpu, me = smp_processor_id();
/* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled());
/* So, what's a CPU they want? Ignoring this one. */
cpu = cpumask_first_and(mask, cpu_online_mask);
- if (cpu == smp_processor_id())
+ if (cpu == me)
cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
/* No online cpus? We're done. */
if (cpu >= nr_cpu_ids)
/* 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())
+ if (next_cpu == me)
next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
/* Fastpath: do that cpu by itself. */
return;
}
- 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;
- }
+ data = &__get_cpu_var(cfd_data);
+ csd_lock(&data->csd);
- spin_lock_init(&data->lock);
- data->csd.flags = CSD_FLAG_ALLOC;
+ spin_lock_irqsave(&data->lock, flags);
if (wait)
- data->csd.flags |= CSD_FLAG_WAIT;
+ csd_wait_prepare(&data->csd);
+
data->csd.func = func;
data->csd.info = info;
- 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));
+ cpumask_and(data->cpumask, mask, cpu_online_mask);
+ cpumask_clear_cpu(me, data->cpumask);
+ data->refs = cpumask_weight(data->cpumask);
- spin_lock_irqsave(&call_function_lock, flags);
- list_add_tail_rcu(&data->csd.list, &call_function_queue);
- spin_unlock_irqrestore(&call_function_lock, flags);
+ spin_lock(&call_function.lock);
+ /*
+ * Place entry at the _HEAD_ of the list, so that any cpu still
+ * observing the entry in generic_smp_call_function_interrupt() will
+ * not miss any other list entries.
+ */
+ list_add_rcu(&data->csd.list, &call_function.queue);
+ spin_unlock(&call_function.lock);
+ spin_unlock_irqrestore(&data->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(to_cpumask(data->cpumask_bits));
+ arch_send_call_function_ipi_mask(data->cpumask);
/* optionally wait for the CPUs to complete */
if (wait)
- csd_flag_wait(&data->csd);
+ csd_wait(&data->csd);
}
EXPORT_SYMBOL(smp_call_function_many);
void ipi_call_lock(void)
{
- spin_lock(&call_function_lock);
+ spin_lock(&call_function.lock);
}
void ipi_call_unlock(void)
{
- spin_unlock(&call_function_lock);
+ spin_unlock(&call_function.lock);
}
void ipi_call_lock_irq(void)
{
- spin_lock_irq(&call_function_lock);
+ spin_lock_irq(&call_function.lock);
}
void ipi_call_unlock_irq(void)
{
- spin_unlock_irq(&call_function_lock);
+ spin_unlock_irq(&call_function.lock);
}
projects / linux-2.6-omap-h63xx.git / commitdiff