[PATCH] net/vdpa: Use reader/writers semaphore instead of mutex
From: Eli Cohen
Date: Wed May 11 2022 - 08:58:59 EST
Use rw_semaphore instead of mutex to control access to vdpa devices.
This can be especially beneficial in case process poll on statistics
information.
Suggested-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
---
drivers/vdpa/vdpa.c | 64 ++++++++++++++++++++++-----------------------
1 file changed, 32 insertions(+), 32 deletions(-)
diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 0fb4a615f267..ced634f94f76 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -18,7 +18,7 @@
static LIST_HEAD(mdev_head);
/* A global mutex that protects vdpa management device and device level operations. */
-static DEFINE_MUTEX(vdpa_dev_mutex);
+static DECLARE_RWSEM(vdpa_dev_lock);
static DEFINE_IDA(vdpa_index_ida);
void vdpa_set_status(struct vdpa_device *vdev, u8 status)
@@ -238,7 +238,7 @@ static int __vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
vdev->nvqs = nvqs;
- lockdep_assert_held(&vdpa_dev_mutex);
+ lockdep_assert_held(&vdpa_dev_lock);
dev = bus_find_device(&vdpa_bus, NULL, dev_name(&vdev->dev), vdpa_name_match);
if (dev) {
put_device(dev);
@@ -278,9 +278,9 @@ int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
{
int err;
- mutex_lock(&vdpa_dev_mutex);
+ down_write(&vdpa_dev_lock);
err = __vdpa_register_device(vdev, nvqs);
- mutex_unlock(&vdpa_dev_mutex);
+ up_write(&vdpa_dev_lock);
return err;
}
EXPORT_SYMBOL_GPL(vdpa_register_device);
@@ -293,7 +293,7 @@ EXPORT_SYMBOL_GPL(vdpa_register_device);
*/
void _vdpa_unregister_device(struct vdpa_device *vdev)
{
- lockdep_assert_held(&vdpa_dev_mutex);
+ lockdep_assert_held(&vdpa_dev_lock);
WARN_ON(!vdev->mdev);
device_unregister(&vdev->dev);
}
@@ -305,9 +305,9 @@ EXPORT_SYMBOL_GPL(_vdpa_unregister_device);
*/
void vdpa_unregister_device(struct vdpa_device *vdev)
{
- mutex_lock(&vdpa_dev_mutex);
+ down_write(&vdpa_dev_lock);
device_unregister(&vdev->dev);
- mutex_unlock(&vdpa_dev_mutex);
+ up_write(&vdpa_dev_lock);
}
EXPORT_SYMBOL_GPL(vdpa_unregister_device);
@@ -352,9 +352,9 @@ int vdpa_mgmtdev_register(struct vdpa_mgmt_dev *mdev)
return -EINVAL;
INIT_LIST_HEAD(&mdev->list);
- mutex_lock(&vdpa_dev_mutex);
+ down_write(&vdpa_dev_lock);
list_add_tail(&mdev->list, &mdev_head);
- mutex_unlock(&vdpa_dev_mutex);
+ up_write(&vdpa_dev_lock);
return 0;
}
EXPORT_SYMBOL_GPL(vdpa_mgmtdev_register);
@@ -371,14 +371,14 @@ static int vdpa_match_remove(struct device *dev, void *data)
void vdpa_mgmtdev_unregister(struct vdpa_mgmt_dev *mdev)
{
- mutex_lock(&vdpa_dev_mutex);
+ down_write(&vdpa_dev_lock);
list_del(&mdev->list);
/* Filter out all the entries belong to this management device and delete it. */
bus_for_each_dev(&vdpa_bus, NULL, mdev, vdpa_match_remove);
- mutex_unlock(&vdpa_dev_mutex);
+ up_write(&vdpa_dev_lock);
}
EXPORT_SYMBOL_GPL(vdpa_mgmtdev_unregister);
@@ -532,17 +532,17 @@ static int vdpa_nl_cmd_mgmtdev_get_doit(struct sk_buff *skb, struct genl_info *i
if (!msg)
return -ENOMEM;
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
mdev = vdpa_mgmtdev_get_from_attr(info->attrs);
if (IS_ERR(mdev)) {
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
NL_SET_ERR_MSG_MOD(info->extack, "Fail to find the specified mgmt device");
err = PTR_ERR(mdev);
goto out;
}
err = vdpa_mgmtdev_fill(mdev, msg, info->snd_portid, info->snd_seq, 0);
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
if (err)
goto out;
err = genlmsg_reply(msg, info);
@@ -561,7 +561,7 @@ vdpa_nl_cmd_mgmtdev_get_dumpit(struct sk_buff *msg, struct netlink_callback *cb)
int idx = 0;
int err;
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
list_for_each_entry(mdev, &mdev_head, list) {
if (idx < start) {
idx++;
@@ -574,7 +574,7 @@ vdpa_nl_cmd_mgmtdev_get_dumpit(struct sk_buff *msg, struct netlink_callback *cb)
idx++;
}
out:
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
cb->args[0] = idx;
return msg->len;
}
@@ -630,7 +630,7 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
- mutex_lock(&vdpa_dev_mutex);
+ down_write(&vdpa_dev_lock);
mdev = vdpa_mgmtdev_get_from_attr(info->attrs);
if (IS_ERR(mdev)) {
NL_SET_ERR_MSG_MOD(info->extack, "Fail to find the specified management device");
@@ -650,7 +650,7 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
err = mdev->ops->dev_add(mdev, name, &config);
err:
- mutex_unlock(&vdpa_dev_mutex);
+ up_write(&vdpa_dev_lock);
return err;
}
@@ -666,7 +666,7 @@ static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *i
return -EINVAL;
name = nla_data(info->attrs[VDPA_ATTR_DEV_NAME]);
- mutex_lock(&vdpa_dev_mutex);
+ down_write(&vdpa_dev_lock);
dev = bus_find_device(&vdpa_bus, NULL, name, vdpa_name_match);
if (!dev) {
NL_SET_ERR_MSG_MOD(info->extack, "device not found");
@@ -684,7 +684,7 @@ static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *i
mdev_err:
put_device(dev);
dev_err:
- mutex_unlock(&vdpa_dev_mutex);
+ up_write(&vdpa_dev_lock);
return err;
}
@@ -750,7 +750,7 @@ static int vdpa_nl_cmd_dev_get_doit(struct sk_buff *skb, struct genl_info *info)
if (!msg)
return -ENOMEM;
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
dev = bus_find_device(&vdpa_bus, NULL, devname, vdpa_name_match);
if (!dev) {
NL_SET_ERR_MSG_MOD(info->extack, "device not found");
@@ -768,13 +768,13 @@ static int vdpa_nl_cmd_dev_get_doit(struct sk_buff *skb, struct genl_info *info)
err = genlmsg_reply(msg, info);
put_device(dev);
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
return err;
mdev_err:
put_device(dev);
err:
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
nlmsg_free(msg);
return err;
}
@@ -816,9 +816,9 @@ static int vdpa_nl_cmd_dev_get_dumpit(struct sk_buff *msg, struct netlink_callba
info.start_idx = cb->args[0];
info.idx = 0;
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
bus_for_each_dev(&vdpa_bus, NULL, &info, vdpa_dev_dump);
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
cb->args[0] = info.idx;
return msg->len;
}
@@ -1016,7 +1016,7 @@ static int vdpa_nl_cmd_dev_config_get_doit(struct sk_buff *skb, struct genl_info
if (!msg)
return -ENOMEM;
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
dev = bus_find_device(&vdpa_bus, NULL, devname, vdpa_name_match);
if (!dev) {
NL_SET_ERR_MSG_MOD(info->extack, "device not found");
@@ -1037,7 +1037,7 @@ static int vdpa_nl_cmd_dev_config_get_doit(struct sk_buff *skb, struct genl_info
mdev_err:
put_device(dev);
dev_err:
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
if (err)
nlmsg_free(msg);
return err;
@@ -1075,9 +1075,9 @@ vdpa_nl_cmd_dev_config_get_dumpit(struct sk_buff *msg, struct netlink_callback *
info.start_idx = cb->args[0];
info.idx = 0;
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
bus_for_each_dev(&vdpa_bus, NULL, &info, vdpa_dev_config_dump);
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
cb->args[0] = info.idx;
return msg->len;
}
@@ -1104,7 +1104,7 @@ static int vdpa_nl_cmd_dev_stats_get_doit(struct sk_buff *skb,
return -ENOMEM;
index = nla_get_u32(info->attrs[VDPA_ATTR_DEV_QUEUE_INDEX]);
- mutex_lock(&vdpa_dev_mutex);
+ down_read(&vdpa_dev_lock);
dev = bus_find_device(&vdpa_bus, NULL, devname, vdpa_name_match);
if (!dev) {
NL_SET_ERR_MSG_MOD(info->extack, "device not found");
@@ -1124,7 +1124,7 @@ static int vdpa_nl_cmd_dev_stats_get_doit(struct sk_buff *skb,
err = genlmsg_reply(msg, info);
put_device(dev);
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
return err;
@@ -1132,7 +1132,7 @@ static int vdpa_nl_cmd_dev_stats_get_doit(struct sk_buff *skb,
put_device(dev);
dev_err:
nlmsg_free(msg);
- mutex_unlock(&vdpa_dev_mutex);
+ up_read(&vdpa_dev_lock);
return err;
}
--
2.35.1