[PATCH 3/9] nvme: change namespaces_mutext to namespaces_rwsem

From: Jianchao Wang
Date: Sun Feb 11 2018 - 04:41:36 EST

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Next in thread: Sagi Grimberg: "Re: [PATCH 3/9] nvme: change namespaces_mutext to namespaces_rwsem"
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namespaces_mutext is used to synchronize the operations on ctrl
namespaces list. Most of the time, it is a read operation. It is
better to change it from mutex to rwsem.

On the other hand, the namespaces mutex could introduce circular
dependency easily.

Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
---
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 7425124..176ba9e 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1120,14 +1120,14 @@ 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_del_init(&ns->list);
list_add_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);
@@ -2437,7 +2437,7 @@ 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;
@@ -2454,14 +2454,14 @@ 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;
}

@@ -2894,7 +2894,7 @@ 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))
@@ -2905,7 +2905,7 @@ 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;
}

@@ -3017,9 +3017,9 @@ 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);

@@ -3072,9 +3072,9 @@ 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);
@@ -3100,14 +3100,14 @@ 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_del_init(&ns->list);
list_add_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);
@@ -3187,9 +3187,9 @@ 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);
}

@@ -3222,9 +3222,9 @@ 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);
@@ -3413,7 +3413,7 @@ 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;
@@ -3474,7 +3474,7 @@ 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)
@@ -3493,7 +3493,7 @@ 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);

@@ -3501,10 +3501,10 @@ 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);

@@ -3512,13 +3512,13 @@ 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);

@@ -3526,10 +3526,10 @@ 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);

@@ -3537,10 +3537,10 @@ 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);

@@ -3548,10 +3548,10 @@ 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);

@@ -3559,10 +3559,10 @@ 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 8e4550f..4191650 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

Next message: Jianchao Wang: "[PATCH V3 0/6]nvme-pci: fixes on nvme_timeout and nvme_dev_disable"
Previous message: Jianchao Wang: "[PATCH 9/9] nvme-pci: discard wait timeout when delete cq/sq"
In reply to: Sagi Grimberg: "Re: [PATCH 9/9] nvme-pci: discard wait timeout when delete cq/sq"
Next in thread: Sagi Grimberg: "Re: [PATCH 3/9] nvme: change namespaces_mutext to namespaces_rwsem"
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