3 files changed, 11 insertions, 89 deletions

diff --git a/block/blk-mq-cpu.c b/block/blk-mq-cpu.c
index 0045ace9bdf0..20576e3476e9 100644
--- a/block/blk-mq-cpu.c
+++ b/block/blk-mq-cpu.c
@@ -28,32 +28,6 @@ static int blk_mq_main_cpu_notify(struct notifier_block *self,
         return NOTIFY_OK;
 }
 
-static void blk_mq_cpu_notify(void *data, unsigned long action,
-                              unsigned int cpu)
-{
-        if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
-                /*
-                 * If the CPU goes away, ensure that we run any pending
-                 * completions.
-                 */
-                struct llist_node *node;
-                struct request *rq;
-
-                local_irq_disable();
-
-                node = llist_del_all(&per_cpu(ipi_lists, cpu));
-                while (node) {
-                        struct llist_node *next = node->next;
-
-                        rq = llist_entry(node, struct request, ll_list);
-                        __blk_mq_end_io(rq, rq->errors);
-                        node = next;
-                }
-
-                local_irq_enable();
-        }
-}
-
 static struct notifier_block __cpuinitdata blk_mq_main_cpu_notifier = {
         .notifier_call  = blk_mq_main_cpu_notify,
 };
@@ -82,12 +56,7 @@ void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
         notifier->data = data;
 }
 
-static struct blk_mq_cpu_notifier __cpuinitdata cpu_notifier = {
-        .notify = blk_mq_cpu_notify,
-};
-
 void __init blk_mq_cpu_init(void)
 {
         register_hotcpu_notifier(&blk_mq_main_cpu_notifier);
-        blk_mq_register_cpu_notifier(&cpu_notifier);
 }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 473ce4039060..68734f87f1da 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -27,8 +27,6 @@ static LIST_HEAD(all_q_list);
 
 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
 
-DEFINE_PER_CPU(struct llist_head, ipi_lists);
-
 static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
                                            unsigned int cpu)
 {
@@ -339,55 +337,12 @@ void __blk_mq_end_io(struct request *rq, int error)
                 blk_mq_complete_request(rq, error);
 }
 
-#if defined(CONFIG_SMP)
-
-/*
- * Called with interrupts disabled.
- */
-static void ipi_end_io(void *data)
+static void blk_mq_end_io_remote(void *data)
 {
-        struct llist_head *list = &per_cpu(ipi_lists, smp_processor_id());
-        struct llist_node *entry, *next;
-        struct request *rq;
-
-        entry = llist_del_all(list);
-
-        while (entry) {
-                next = entry->next;
-                rq = llist_entry(entry, struct request, ll_list);
-                __blk_mq_end_io(rq, rq->errors);
-                entry = next;
-        }
-}
-
-static int ipi_remote_cpu(struct blk_mq_ctx *ctx, const int cpu,
-                          struct request *rq, const int error)
-{
-        struct call_single_data *data = &rq->csd;
-
-        rq->errors = error;
-        rq->ll_list.next = NULL;
-
-        /*
-         * If the list is non-empty, an existing IPI must already
-         * be "in flight". If that is the case, we need not schedule
-         * a new one.
-         */
-        if (llist_add(&rq->ll_list, &per_cpu(ipi_lists, ctx->cpu))) {
-                data->func = ipi_end_io;
-                data->flags = 0;
-                __smp_call_function_single(ctx->cpu, data, 0);
-        }
+        struct request *rq = data;
 
-        return true;
+        __blk_mq_end_io(rq, rq->errors);
 }
-#else /* CONFIG_SMP */
-static int ipi_remote_cpu(struct blk_mq_ctx *ctx, const int cpu,
-                          struct request *rq, const int error)
-{
-        return false;
-}
-#endif
 
 /*
  * End IO on this request on a multiqueue enabled driver. We'll either do
@@ -403,11 +358,15 @@ void blk_mq_end_io(struct request *rq, int error)
                 return __blk_mq_end_io(rq, error);
 
         cpu = get_cpu();
-
-        if (cpu == ctx->cpu || !cpu_online(ctx->cpu) ||
-            !ipi_remote_cpu(ctx, cpu, rq, error))
+        if (cpu != ctx->cpu && cpu_online(ctx->cpu)) {
+                rq->errors = error;
+                rq->csd.func = blk_mq_end_io_remote;
+                rq->csd.info = rq;
+                rq->csd.flags = 0;
+                __smp_call_function_single(ctx->cpu, &rq->csd, 0);
+        } else {
                 __blk_mq_end_io(rq, error);
-
+        }
         put_cpu();
 }
 EXPORT_SYMBOL(blk_mq_end_io);
@@ -1506,11 +1465,6 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
 
 static int __init blk_mq_init(void)
 {
-        unsigned int i;
-
-        for_each_possible_cpu(i)
-                init_llist_head(&per_cpu(ipi_lists, i));
-
         blk_mq_cpu_init();
 
         /* Must be called after percpu_counter_hotcpu_callback() */
diff --git a/block/blk-mq.h b/block/blk-mq.h
index e151a2f4f171..5c3917984b00 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -40,7 +40,6 @@ void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
 void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier);
 void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier);
 void blk_mq_cpu_init(void);
-DECLARE_PER_CPU(struct llist_head, ipi_lists);
 
 /*
  * CPU -> queue mappings