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Subject[PATCH 7/7] blk-mq: use __smp_call_function_single directly
Now that __smp_call_function_single is available for all builds and
uses llists to queue up items without taking a lock or disabling
interrupts there is no need to wrap around it in the block code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/blk-mq-cpu.c | 31 ------------------------
block/blk-mq.c | 68 +++++++++-------------------------------------------
block/blk-mq.h | 1 -
3 files changed, 11 insertions(+), 89 deletions(-)

diff --git a/block/blk-mq-cpu.c b/block/blk-mq-cpu.c
index f8ea39d..4f0c352 100644
--- a/block/blk-mq-cpu.c
+++ b/block/blk-mq-cpu.c
@@ -28,32 +28,6 @@ static int __cpuinit blk_mq_main_cpu_notify(struct notifier_block *self,
return NOTIFY_OK;
}

-static void __cpuinit 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 d43a7e8..0b2b487 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)
{
@@ -318,55 +316,12 @@ 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
@@ -382,11 +337,15 @@ 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);
@@ -1465,11 +1424,6 @@ static int __cpuinit 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 52bf1f9..5761eed 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -38,7 +38,6 @@ 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
--
1.7.10.4



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