1 files changed, 86 insertions, 76 deletions

diff --git a/kernel/smp.c b/kernel/smp.c
index f5308258891a..7ad2262d2eca 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -2,13 +2,12 @@
  * Generic helpers for smp ipi calls
  *
  * (C) Jens Axboe <jens.axboe@oracle.com> 2008
- *
  */
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/percpu.h>
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
 #include <linux/smp.h>
 #include <linux/cpu.h>
 
@@ -17,29 +16,30 @@ static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
 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),
-};
+} call_function __cacheline_aligned_in_smp =
+        {
+                .queue          = LIST_HEAD_INIT(call_function.queue),
+                .lock           = __SPIN_LOCK_UNLOCKED(call_function.lock),
+        };
 
 enum {
         CSD_FLAG_LOCK           = 0x01,
 };
 
 struct call_function_data {
-        struct call_single_data csd;
-        spinlock_t lock;
-        unsigned int refs;
-        cpumask_var_t cpumask;
+        struct call_single_data csd;
+        spinlock_t              lock;
+        unsigned int            refs;
+        cpumask_var_t           cpumask;
 };
 
 struct call_single_queue {
-        struct list_head list;
-        spinlock_t lock;
+        struct list_head        list;
+        spinlock_t              lock;
 };
 
 static DEFINE_PER_CPU(struct call_function_data, cfd_data) = {
-        .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
+        .lock                   = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
 };
 
 static int
@@ -71,7 +71,7 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
 }
 
 static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
-        .notifier_call = hotplug_cfd,
+        .notifier_call          = hotplug_cfd,
 };
 
 static int __cpuinit init_call_single_data(void)
@@ -96,9 +96,9 @@ early_initcall(init_call_single_data);
 /*
  * 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.
+ * 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_wait(struct call_single_data *data)
 {
@@ -112,27 +112,29 @@ static void csd_lock(struct call_single_data *data)
         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.
+         * 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
+         * ensure we're all done before releasing data:
          */
         smp_mb();
+
         data->flags &= ~CSD_FLAG_LOCK;
 }
 
 /*
- * Insert a previously allocated call_single_data element for execution
- * on the given CPU. data must already have ->func, ->info, and ->flags set.
+ * 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, int wait)
@@ -154,10 +156,9 @@ void generic_exec_single(int cpu, struct call_single_data *data, int wait)
          * If IPIs can go out of order to the cache coherency protocol
          * in an architecture, sufficient synchronisation should be added
          * to arch code to make it appear to obey cache coherency WRT
-         * locking and barrier primitives. Generic code isn't really equipped
-         * to do the right thing...
+         * locking and barrier primitives. Generic code isn't really
+         * equipped to do the right thing...
          */
-
         if (ipi)
                 arch_send_call_function_single_ipi(cpu);
 
@@ -183,8 +184,8 @@ void generic_smp_call_function_interrupt(void)
         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
+         * 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;
@@ -219,14 +220,14 @@ void generic_smp_call_function_interrupt(void)
 }
 
 /*
- * Invoked by arch to handle an IPI for call function single. Must be called
- * from the arch with interrupts disabled.
+ * Invoked by arch to handle an IPI for call function single. Must be
+ * called from the arch with interrupts disabled.
  */
 void generic_smp_call_function_single_interrupt(void)
 {
         struct call_single_queue *q = &__get_cpu_var(call_single_queue);
-        LIST_HEAD(list);
         unsigned int data_flags;
+        LIST_HEAD(list);
 
         spin_lock(&q->lock);
         list_replace_init(&q->list, &list);
@@ -235,22 +236,20 @@ void generic_smp_call_function_single_interrupt(void)
         while (!list_empty(&list)) {
                 struct call_single_data *data;
 
-                data = list_entry(list.next, struct call_single_data,
-                                        list);
+                data = list_entry(list.next, struct call_single_data, list);
                 list_del(&data->list);
 
                 /*
-                 * 'data' can be invalid after this call if
-                 * flags == 0 (when called through
-                 * generic_exec_single(), so save them away before
-                 * making the call.
+                 * 'data' can be invalid after this call if flags == 0
+                 * (when called through generic_exec_single()),
+                 * so save them away before making the call:
                  */
                 data_flags = data->flags;
 
                 data->func(data->info);
 
                 /*
-                 * Unlocked CSDs are valid through generic_exec_single()
+                 * Unlocked CSDs are valid through generic_exec_single():
                  */
                 if (data_flags & CSD_FLAG_LOCK)
                         csd_unlock(data);
@@ -276,34 +275,41 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
                 .flags = 0,
         };
         unsigned long flags;
-        /* prevent preemption and reschedule on another processor,
-           as well as CPU removal */
-        int me = get_cpu();
+        int this_cpu;
         int err = 0;
 
+        /*
+         * prevent preemption and reschedule on another processor,
+         * as well as CPU removal
+         */
+        this_cpu = get_cpu();
+
         /* Can deadlock when called with interrupts disabled */
         WARN_ON(irqs_disabled());
 
-        if (cpu == me) {
+        if (cpu == this_cpu) {
                 local_irq_save(flags);
                 func(info);
                 local_irq_restore(flags);
-        } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
-                struct call_single_data *data = &d;
+        } else {
+                if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
+                        struct call_single_data *data = &d;
 
-                if (!wait)
-                        data = &__get_cpu_var(csd_data);
+                        if (!wait)
+                                data = &__get_cpu_var(csd_data);
 
-                csd_lock(data);
+                        csd_lock(data);
 
-                data->func = func;
-                data->info = info;
-                generic_exec_single(cpu, data, wait);
-        } else {
-                err = -ENXIO;   /* CPU not online */
+                        data->func = func;
+                        data->info = info;
+                        generic_exec_single(cpu, data, wait);
+                } else {
+                        err = -ENXIO;   /* CPU not online */
+                }
         }
 
         put_cpu();
+
         return err;
 }
 EXPORT_SYMBOL(smp_call_function_single);
@@ -313,10 +319,9 @@ EXPORT_SYMBOL(smp_call_function_single);
  * @cpu: The CPU to run on.
  * @data: Pre-allocated and setup data structure
  *
- * Like smp_call_function_single(), but allow caller to pass in a pre-allocated
- * data structure. Useful for embedding @data inside other structures, for
- * instance.
- *
+ * Like smp_call_function_single(), but allow caller to pass in a
+ * pre-allocated data structure. Useful for embedding @data inside
+ * other structures, for instance.
  */
 void __smp_call_function_single(int cpu, struct call_single_data *data,
                                 int wait)
@@ -329,10 +334,11 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
         generic_exec_single(cpu, data, wait);
 }
 
-/* FIXME: Shim for archs using old arch_send_call_function_ipi API. */
+/* Deprecated: 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))
+# define arch_send_call_function_ipi_mask(maskp) \
+         arch_send_call_function_ipi(*(maskp))
 #endif
 
 /**
@@ -340,7 +346,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
  * @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.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
  *
  * If @wait is true, then returns once @func has returned. Note that @wait
  * will be implicitly turned on in case of allocation failures, since
@@ -351,27 +358,27 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
  * must be disabled when calling this function.
  */
 void smp_call_function_many(const struct cpumask *mask,
-                            void (*func)(void *), void *info,
-                            bool wait)
+                            void (*func)(void *), void *info, bool wait)
 {
         struct call_function_data *data;
         unsigned long flags;
-        int cpu, next_cpu, me = smp_processor_id();
+        int cpu, next_cpu, this_cpu = smp_processor_id();
 
         /* Can deadlock when called with interrupts disabled */
         WARN_ON(irqs_disabled());
 
-        /* So, what's a CPU they want?  Ignoring this one. */
+        /* So, what's a CPU they want? Ignoring this one. */
         cpu = cpumask_first_and(mask, cpu_online_mask);
-        if (cpu == me)
+        if (cpu == this_cpu)
                 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 == me)
+        if (next_cpu == this_cpu)
                 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
 
         /* Fastpath: do that cpu by itself. */
@@ -387,30 +394,31 @@ void smp_call_function_many(const struct cpumask *mask,
         data->csd.func = func;
         data->csd.info = info;
         cpumask_and(data->cpumask, mask, cpu_online_mask);
-        cpumask_clear_cpu(me, data->cpumask);
+        cpumask_clear_cpu(this_cpu, data->cpumask);
         data->refs = cpumask_weight(data->cpumask);
 
         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.
+         * 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.
-         * (IPIs must obey or appear to obey normal Linux cache coherency
-         * rules -- see comment in generic_exec_single).
+         * (IPIs must obey or appear to obey normal Linux cache
+         * coherency rules -- see comment in generic_exec_single).
          */
         smp_mb();
 
         /* Send a message to all CPUs in the map */
         arch_send_call_function_ipi_mask(data->cpumask);
 
-        /* optionally wait for the CPUs to complete */
+        /* Optionally wait for the CPUs to complete */
         if (wait)
                 csd_lock_wait(&data->csd);
 }
@@ -420,7 +428,8 @@ EXPORT_SYMBOL(smp_call_function_many);
  * smp_call_function(): Run a function on all other CPUs.
  * @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.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
  *
  * Returns 0.
  *
@@ -436,6 +445,7 @@ int smp_call_function(void (*func)(void *), void *info, int wait)
         preempt_disable();
         smp_call_function_many(cpu_online_mask, func, info, wait);
         preempt_enable();
+
         return 0;
 }
 EXPORT_SYMBOL(smp_call_function);