From 0bf77e9dbb5247ae159342db6f8fdb48aba24b56 Mon Sep 17 00:00:00 2001
From: Ming Lin <ming.l@ssi.samsung.com>
Date: Mon, 25 Apr 2016 14:20:18 -0700
Subject: [PATCH] nvme: switch to RCU freeing the namespace
Switch to RCU freeing the namespace structure so that
nvme_start_queues, nvme_stop_queues and nvme_kill_queues would
be able to get away with only a RCU read side critical section.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimerg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
---
drivers/nvme/host/core.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 3cf366ab66e94..3428c02324030 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1429,7 +1429,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
if (nvme_revalidate_disk(ns->disk))
goto out_free_disk;
- list_add_tail(&ns->list, &ctrl->namespaces);
+ list_add_tail_rcu(&ns->list, &ctrl->namespaces);
kref_get(&ctrl->kref);
if (ns->type == NVME_NS_LIGHTNVM)
return;
@@ -1467,6 +1467,7 @@ static void nvme_ns_remove(struct nvme_ns *ns)
mutex_lock(&ns->ctrl->namespaces_mutex);
list_del_init(&ns->list);
mutex_unlock(&ns->ctrl->namespaces_mutex);
+ synchronize_rcu();
nvme_put_ns(ns);
}
@@ -1751,8 +1752,8 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
- list_for_each_entry(ns, &ctrl->namespaces, list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {
if (!kref_get_unless_zero(&ns->kref))
continue;
@@ -1769,7 +1770,7 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
nvme_put_ns(ns);
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nvme_kill_queues);
@@ -1777,8 +1778,8 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
- list_for_each_entry(ns, &ctrl->namespaces, list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {
spin_lock_irq(ns->queue->queue_lock);
queue_flag_set(QUEUE_FLAG_STOPPED, ns->queue);
spin_unlock_irq(ns->queue->queue_lock);
@@ -1786,7 +1787,7 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
blk_mq_cancel_requeue_work(ns->queue);
blk_mq_stop_hw_queues(ns->queue);
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nvme_stop_queues);
@@ -1794,13 +1795,13 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
- list_for_each_entry(ns, &ctrl->namespaces, list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {
queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, ns->queue);
blk_mq_start_stopped_hw_queues(ns->queue, true);
blk_mq_kick_requeue_list(ns->queue);
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nvme_start_queues);
--
2.30.2