#include "smpboot.h"
#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
-static struct {
- struct list_head queue;
- raw_spinlock_t lock;
-} call_function __cacheline_aligned_in_smp =
- {
- .queue = LIST_HEAD_INIT(call_function.queue),
- .lock = __RAW_SPIN_LOCK_UNLOCKED(call_function.lock),
- };
-
enum {
CSD_FLAG_LOCK = 0x01,
};
struct call_function_data {
- struct call_single_data csd;
- atomic_t refs;
+ struct call_single_data __percpu *csd;
cpumask_var_t cpumask;
cpumask_var_t cpumask_ipi;
};
if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
cpu_to_node(cpu)))
return notifier_from_errno(-ENOMEM);
+ cfd->csd = alloc_percpu(struct call_single_data);
+ if (!cfd->csd) {
+ free_cpumask_var(cfd->cpumask);
+ return notifier_from_errno(-ENOMEM);
+ }
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DEAD_FROZEN:
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
+ free_percpu(cfd->csd);
break;
#endif
};
csd_lock_wait(data);
}
-/*
- * Invoked by arch to handle an IPI for call function. Must be called with
- * interrupts disabled.
- */
-void generic_smp_call_function_interrupt(void)
-{
- struct call_function_data *data;
- int cpu = smp_processor_id();
-
- /*
- * Shouldn't receive this interrupt on a cpu that is not yet online.
- */
- WARN_ON_ONCE(!cpu_online(cpu));
-
- /*
- * Ensure entry is visible on call_function_queue after we have
- * entered the IPI. See comment in smp_call_function_many.
- * If we don't have this, then we may miss an entry on the list
- * and never get another IPI to process it.
- */
- smp_mb();
-
- /*
- * It's ok to use list_for_each_rcu() here even though we may
- * delete 'pos', since list_del_rcu() doesn't clear ->next
- */
- list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
- int refs;
- smp_call_func_t func;
-
- /*
- * Since we walk the list without any locks, we might
- * see an entry that was completed, removed from the
- * list and is in the process of being reused.
- *
- * We must check that the cpu is in the cpumask before
- * checking the refs, and both must be set before
- * executing the callback on this cpu.
- */
-
- if (!cpumask_test_cpu(cpu, data->cpumask))
- continue;
-
- smp_rmb();
-
- if (atomic_read(&data->refs) == 0)
- continue;
-
- func = data->csd.func; /* save for later warn */
- func(data->csd.info);
-
- /*
- * If the cpu mask is not still set then func enabled
- * interrupts (BUG), and this cpu took another smp call
- * function interrupt and executed func(info) twice
- * on this cpu. That nested execution decremented refs.
- */
- if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) {
- WARN(1, "%pf enabled interrupts and double executed\n", func);
- continue;
- }
-
- refs = atomic_dec_return(&data->refs);
- WARN_ON(refs < 0);
-
- if (refs)
- continue;
-
- WARN_ON(!cpumask_empty(data->cpumask));
-
- raw_spin_lock(&call_function.lock);
- list_del_rcu(&data->csd.list);
- raw_spin_unlock(&call_function.lock);
-
- csd_unlock(&data->csd);
- }
-
-}
-
/*
* Invoked by arch to handle an IPI for call function single. Must be
* called from the arch with interrupts disabled.
smp_call_func_t func, void *info, bool wait)
{
struct call_function_data *data;
- unsigned long flags;
- int refs, cpu, next_cpu, this_cpu = smp_processor_id();
+ int cpu, next_cpu, this_cpu = smp_processor_id();
/*
* Can deadlock when called with interrupts disabled.
}
data = &__get_cpu_var(cfd_data);
- csd_lock(&data->csd);
-
- /* This BUG_ON verifies our reuse assertions and can be removed */
- BUG_ON(atomic_read(&data->refs) || !cpumask_empty(data->cpumask));
-
- /*
- * The global call function queue list add and delete are protected
- * by a lock, but the list is traversed without any lock, relying
- * on the rcu list add and delete to allow safe concurrent traversal.
- * We reuse the call function data without waiting for any grace
- * period after some other cpu removes it from the global queue.
- * This means a cpu might find our data block as it is being
- * filled out.
- *
- * We hold off the interrupt handler on the other cpu by
- * ordering our writes to the cpu mask vs our setting of the
- * refs counter. We assert only the cpu owning the data block
- * will set a bit in cpumask, and each bit will only be cleared
- * by the subject cpu. Each cpu must first find its bit is
- * set and then check that refs is set indicating the element is
- * ready to be processed, otherwise it must skip the entry.
- *
- * On the previous iteration refs was set to 0 by another cpu.
- * To avoid the use of transitivity, set the counter to 0 here
- * so the wmb will pair with the rmb in the interrupt handler.
- */
- atomic_set(&data->refs, 0); /* convert 3rd to 1st party write */
-
- data->csd.func = func;
- data->csd.info = info;
- /* Ensure 0 refs is visible before mask. Also orders func and info */
- smp_wmb();
-
- /* We rely on the "and" being processed before the store */
cpumask_and(data->cpumask, mask, cpu_online_mask);
cpumask_clear_cpu(this_cpu, data->cpumask);
- refs = cpumask_weight(data->cpumask);
/* Some callers race with other cpus changing the passed mask */
- if (unlikely(!refs)) {
- csd_unlock(&data->csd);
+ if (unlikely(!cpumask_weight(data->cpumask)))
return;
- }
/*
* After we put an entry into the list, data->cpumask
* a SMP function call, so data->cpumask will be zero.
*/
cpumask_copy(data->cpumask_ipi, data->cpumask);
- raw_spin_lock_irqsave(&call_function.lock, flags);
- /*
- * 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);
- /*
- * We rely on the wmb() in list_add_rcu to complete our writes
- * to the cpumask before this write to refs, which indicates
- * data is on the list and is ready to be processed.
- */
- atomic_set(&data->refs, refs);
- raw_spin_unlock_irqrestore(&call_function.lock, flags);
- /*
- * Make the list addition visible before sending the ipi.
- * (IPIs must obey or appear to obey normal Linux cache
- * coherency rules -- see comment in generic_exec_single).
- */
- smp_mb();
+ for_each_cpu(cpu, data->cpumask) {
+ struct call_single_data *csd = per_cpu_ptr(data->csd, cpu);
+ struct call_single_queue *dst =
+ &per_cpu(call_single_queue, cpu);
+ unsigned long flags;
+
+ csd_lock(csd);
+ csd->func = func;
+ csd->info = info;
+
+ raw_spin_lock_irqsave(&dst->lock, flags);
+ list_add_tail(&csd->list, &dst->list);
+ raw_spin_unlock_irqrestore(&dst->lock, flags);
+ }
/* Send a message to all CPUs in the map */
arch_send_call_function_ipi_mask(data->cpumask_ipi);
- /* Optionally wait for the CPUs to complete */
- if (wait)
- csd_lock_wait(&data->csd);
+ if (wait) {
+ for_each_cpu(cpu, data->cpumask) {
+ struct call_single_data *csd =
+ per_cpu_ptr(data->csd, cpu);
+ csd_lock_wait(csd);
+ }
+ }
}
EXPORT_SYMBOL(smp_call_function_many);
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