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Message-Id: <1518440086-583-3-git-send-email-jianchao.w.wang@oracle.com>
Date: Mon, 12 Feb 2018 20:54:46 +0800
From: Jianchao Wang <jianchao.w.wang@...cle.com>
To: keith.busch@...el.com, axboe@...com, hch@....de, sagi@...mberg.me
Cc: linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] nvme: change namespaces_mutext to namespaces_rwsem
namespaces_mutext is used to synchronize the operations on ctrl
namespaces list. Most of the time, it is a read operation.
On the other hand, there are many interfaces in nvme core that
need this lock, such as nvme_wait_freeze, and even more interfaces
will be added. If we use mutex here, circular dependency could be
introduced easily. For example:
context A context B
nvme_xxx nvme_xxx
hold namespaces_mutext require namespaces_mutext
sync context B
So it is better to change it from mutex to rwsem.
Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
---
drivers/nvme/host/core.c | 64 +++++++++++++++++++++----------------------
drivers/nvme/host/multipath.c | 4 +--
drivers/nvme/host/nvme.h | 2 +-
3 files changed, 35 insertions(+), 35 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a051c2f..e8a3671 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1122,13 +1122,13 @@ static void nvme_update_formats(struct nvme_ctrl *ctrl)
struct nvme_ns *ns, *next;
LIST_HEAD(rm_list);
- mutex_lock(&ctrl->namespaces_mutex);
+ down_write(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list) {
if (ns->disk && nvme_revalidate_disk(ns->disk)) {
list_move_tail(&ns->list, &rm_list);
}
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_write(&ctrl->namespaces_rwsem);
list_for_each_entry_safe(ns, next, &rm_list, list)
nvme_ns_remove(ns);
@@ -2438,7 +2438,7 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp)
struct nvme_ns *ns;
int ret;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
if (list_empty(&ctrl->namespaces)) {
ret = -ENOTTY;
goto out_unlock;
@@ -2455,14 +2455,14 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp)
dev_warn(ctrl->device,
"using deprecated NVME_IOCTL_IO_CMD ioctl on the char device!\n");
kref_get(&ns->kref);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
ret = nvme_user_cmd(ctrl, ns, argp);
nvme_put_ns(ns);
return ret;
out_unlock:
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
return ret;
}
@@ -2895,7 +2895,7 @@ static struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid)
{
struct nvme_ns *ns, *ret = NULL;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list) {
if (ns->head->ns_id == nsid) {
if (!kref_get_unless_zero(&ns->kref))
@@ -2906,7 +2906,7 @@ static struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid)
if (ns->head->ns_id > nsid)
break;
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
return ret;
}
@@ -3018,9 +3018,9 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
__nvme_revalidate_disk(disk, id);
- mutex_lock(&ctrl->namespaces_mutex);
+ down_write(&ctrl->namespaces_rwsem);
list_add_tail(&ns->list, &ctrl->namespaces);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_write(&ctrl->namespaces_rwsem);
nvme_get_ctrl(ctrl);
@@ -3073,9 +3073,9 @@ static void nvme_ns_remove(struct nvme_ns *ns)
list_del_rcu(&ns->siblings);
mutex_unlock(&ns->ctrl->subsys->lock);
- mutex_lock(&ns->ctrl->namespaces_mutex);
+ down_write(&ns->ctrl->namespaces_rwsem);
list_del_init(&ns->list);
- mutex_unlock(&ns->ctrl->namespaces_mutex);
+ up_write(&ns->ctrl->namespaces_rwsem);
synchronize_srcu(&ns->head->srcu);
nvme_mpath_check_last_path(ns);
@@ -3101,12 +3101,12 @@ static void nvme_remove_invalid_namespaces(struct nvme_ctrl *ctrl,
struct nvme_ns *ns, *next;
LIST_HEAD(rm_list);
- mutex_lock(&ctrl->namespaces_mutex);
+ down_write(&ctrl->namespaces_rwsem);
list_for_each_entry_safe(ns, next, &ctrl->namespaces, list) {
if (ns->head->ns_id > nsid)
list_move_tail(&ns->list, &rm_list);
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_write(&ctrl->namespaces_rwsem);
list_for_each_entry_safe(ns, next, &rm_list, list)
nvme_ns_remove(ns);
@@ -3186,9 +3186,9 @@ static void nvme_scan_work(struct work_struct *work)
}
nvme_scan_ns_sequential(ctrl, nn);
done:
- mutex_lock(&ctrl->namespaces_mutex);
+ down_write(&ctrl->namespaces_rwsem);
list_sort(NULL, &ctrl->namespaces, ns_cmp);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_write(&ctrl->namespaces_rwsem);
kfree(id);
}
@@ -3221,9 +3221,9 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
if (ctrl->state == NVME_CTRL_DEAD)
nvme_kill_queues(ctrl);
- mutex_lock(&ctrl->namespaces_mutex);
+ down_write(&ctrl->namespaces_rwsem);
list_splice_init(&ctrl->namespaces, &ns_list);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_write(&ctrl->namespaces_rwsem);
list_for_each_entry_safe(ns, next, &ns_list, list)
nvme_ns_remove(ns);
@@ -3412,7 +3412,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
ctrl->state = NVME_CTRL_NEW;
spin_lock_init(&ctrl->lock);
INIT_LIST_HEAD(&ctrl->namespaces);
- mutex_init(&ctrl->namespaces_mutex);
+ init_rwsem(&ctrl->namespaces_rwsem);
ctrl->dev = dev;
ctrl->ops = ops;
ctrl->quirks = quirks;
@@ -3473,7 +3473,7 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
/* Forcibly unquiesce queues to avoid blocking dispatch */
if (ctrl->admin_q)
@@ -3492,7 +3492,7 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
/* Forcibly unquiesce queues to avoid blocking dispatch */
blk_mq_unquiesce_queue(ns->queue);
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_kill_queues);
@@ -3500,10 +3500,10 @@ void nvme_unfreeze(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list)
blk_mq_unfreeze_queue(ns->queue);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_unfreeze);
@@ -3511,13 +3511,13 @@ void nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl, long timeout)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list) {
timeout = blk_mq_freeze_queue_wait_timeout(ns->queue, timeout);
if (timeout <= 0)
break;
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_wait_freeze_timeout);
@@ -3525,10 +3525,10 @@ void nvme_wait_freeze(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list)
blk_mq_freeze_queue_wait(ns->queue);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_wait_freeze);
@@ -3536,10 +3536,10 @@ void nvme_start_freeze(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list)
blk_freeze_queue_start(ns->queue);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_start_freeze);
@@ -3547,10 +3547,10 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list)
blk_mq_quiesce_queue(ns->queue);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_stop_queues);
@@ -3558,10 +3558,10 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list)
blk_mq_unquiesce_queue(ns->queue);
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
EXPORT_SYMBOL_GPL(nvme_start_queues);
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 3b211d9..559b601 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -44,12 +44,12 @@ void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
- mutex_lock(&ctrl->namespaces_mutex);
+ down_read(&ctrl->namespaces_rwsem);
list_for_each_entry(ns, &ctrl->namespaces, list) {
if (ns->head->disk)
kblockd_schedule_work(&ns->head->requeue_work);
}
- mutex_unlock(&ctrl->namespaces_mutex);
+ up_read(&ctrl->namespaces_rwsem);
}
static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 27e31c0..d90f638 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -140,7 +140,7 @@ struct nvme_ctrl {
struct blk_mq_tag_set *tagset;
struct blk_mq_tag_set *admin_tagset;
struct list_head namespaces;
- struct mutex namespaces_mutex;
+ struct rw_semaphore namespaces_rwsem;
struct device ctrl_device;
struct device *device; /* char device */
struct cdev cdev;
--
2.7.4
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