1 files changed, 65 insertions, 74 deletions

diff --git a/kernel/smp.c b/kernel/smp.c
index ffee35bef179..06d574e42c72 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -117,13 +117,43 @@ static void csd_unlock(struct call_single_data *csd)
         csd->flags &= ~CSD_FLAG_LOCK;
 }
 
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_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 *csd, int wait)
+static int generic_exec_single(int cpu, struct call_single_data *csd,
+                               smp_call_func_t func, void *info, int wait)
 {
+        struct call_single_data csd_stack = { .flags = 0 };
+        unsigned long flags;
+
+
+        if (cpu == smp_processor_id()) {
+                local_irq_save(flags);
+                func(info);
+                local_irq_restore(flags);
+                return 0;
+        }
+
+
+        if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu))
+                return -ENXIO;
+
+
+        if (!csd) {
+                csd = &csd_stack;
+                if (!wait)
+                        csd = &__get_cpu_var(csd_data);
+        }
+
+        csd_lock(csd);
+
+        csd->func = func;
+        csd->info = info;
+
         if (wait)
                 csd->flags |= CSD_FLAG_WAIT;
 
@@ -143,6 +173,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
 
         if (wait)
                 csd_lock_wait(csd);
+
+        return 0;
 }
 
 /*
@@ -151,7 +183,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
  */
 void generic_smp_call_function_single_interrupt(void)
 {
-        struct llist_node *entry, *next;
+        struct llist_node *entry;
+        struct call_single_data *csd, *csd_next;
 
         /*
          * Shouldn't receive this interrupt on a cpu that is not yet online.
@@ -161,21 +194,12 @@ void generic_smp_call_function_single_interrupt(void)
         entry = llist_del_all(&__get_cpu_var(call_single_queue));
         entry = llist_reverse_order(entry);
 
-        while (entry) {
-                struct call_single_data *csd;
-
-                next = entry->next;
-
-                csd = llist_entry(entry, struct call_single_data, llist);
+        llist_for_each_entry_safe(csd, csd_next, entry, llist) {
                 csd->func(csd->info);
                 csd_unlock(csd);
-
-                entry = next;
         }
 }
 
-static DEFINE_PER_CPU_SHARED_ALIGNED(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.
@@ -187,12 +211,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
 int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
                              int wait)
 {
-        struct call_single_data d = {
-                .flags = 0,
-        };
-        unsigned long flags;
         int this_cpu;
-        int err = 0;
+        int err;
 
         /*
          * prevent preemption and reschedule on another processor,
@@ -209,32 +229,41 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
         WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
                      && !oops_in_progress);
 
-        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 *csd = &d;
+        err = generic_exec_single(cpu, NULL, func, info, wait);
 
-                        if (!wait)
-                                csd = &__get_cpu_var(csd_data);
+        put_cpu();
 
-                        csd_lock(csd);
+        return err;
+}
+EXPORT_SYMBOL(smp_call_function_single);
 
-                        csd->func = func;
-                        csd->info = info;
-                        generic_exec_single(cpu, csd, wait);
-                } else {
-                        err = -ENXIO;   /* CPU not online */
-                }
-        }
+/**
+ * smp_call_function_single_async(): Run an asynchronous function on a
+ *                               specific CPU.
+ * @cpu: The CPU to run on.
+ * @csd: Pre-allocated and setup data structure
+ *
+ * Like smp_call_function_single(), but the call is asynchonous and
+ * can thus be done from contexts with disabled interrupts.
+ *
+ * The caller passes his own pre-allocated data structure
+ * (ie: embedded in an object) and is responsible for synchronizing it
+ * such that the IPIs performed on the @csd are strictly serialized.
+ *
+ * NOTE: Be careful, there is unfortunately no current debugging facility to
+ * validate the correctness of this serialization.
+ */
+int smp_call_function_single_async(int cpu, struct call_single_data *csd)
+{
+        int err = 0;
 
-        put_cpu();
+        preempt_disable();
+        err = generic_exec_single(cpu, csd, csd->func, csd->info, 0);
+        preempt_enable();
 
         return err;
 }
-EXPORT_SYMBOL(smp_call_function_single);
+EXPORT_SYMBOL_GPL(smp_call_function_single_async);
 
 /*
  * smp_call_function_any - Run a function on any of the given cpus
@@ -280,44 +309,6 @@ call:
 EXPORT_SYMBOL_GPL(smp_call_function_any);
 
 /**
- * __smp_call_function_single(): Run a function on a specific CPU
- * @cpu: The CPU to run on.
- * @data: Pre-allocated and setup data structure
- * @wait: If true, wait until function has completed on specified CPU.
- *
- * 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 *csd,
-                                int wait)
-{
-        unsigned int this_cpu;
-        unsigned long flags;
-
-        this_cpu = get_cpu();
-        /*
-         * Can deadlock when called with interrupts disabled.
-         * We allow cpu's that are not yet online though, as no one else can
-         * send smp call function interrupt to this cpu and as such deadlocks
-         * can't happen.
-         */
-        WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
-                     && !oops_in_progress);
-
-        if (cpu == this_cpu) {
-                local_irq_save(flags);
-                csd->func(csd->info);
-                local_irq_restore(flags);
-        } else {
-                csd_lock(csd);
-                generic_exec_single(cpu, csd, wait);
-        }
-        put_cpu();
-}
-EXPORT_SYMBOL_GPL(__smp_call_function_single);
-
-/**
  * 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.