[PATCH v5 1/6] vduse: make domain_lock an rwlock

["Eugenio Pérez" <eperezma@redhat.com>]

It will be used in a few more scenarios read-only so make it more
scalable.

Suggested-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Xie Yongji <xieyongji@bytedance.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
v2: New in v2
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 41 +++++++++++++++---------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index e7bced0b5542..2b6a8958ffe0 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -14,6 +14,7 @@
 #include <linux/cdev.h>
 #include <linux/device.h>
 #include <linux/eventfd.h>
+#include <linux/rwlock.h>
 #include <linux/slab.h>
 #include <linux/wait.h>
 #include <linux/dma-map-ops.h>
@@ -117,7 +118,7 @@ struct vduse_dev {
 	struct vduse_umem *umem;
 	struct mutex mem_lock;
 	unsigned int bounce_size;
-	struct mutex domain_lock;
+	rwlock_t domain_lock;
 };
 
 struct vduse_dev_msg {
@@ -1176,9 +1177,9 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 		if (entry.start > entry.last)
 			break;
 
-		mutex_lock(&dev->domain_lock);
+		read_lock(&dev->domain_lock);
 		if (!dev->domain) {
-			mutex_unlock(&dev->domain_lock);
+			read_unlock(&dev->domain_lock);
 			break;
 		}
 		spin_lock(&dev->domain->iotlb_lock);
@@ -1193,7 +1194,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 			entry.perm = map->perm;
 		}
 		spin_unlock(&dev->domain->iotlb_lock);
-		mutex_unlock(&dev->domain_lock);
+		read_unlock(&dev->domain_lock);
 		ret = -EINVAL;
 		if (!f)
 			break;
@@ -1346,10 +1347,10 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 				 sizeof(umem.reserved)))
 			break;
 
-		mutex_lock(&dev->domain_lock);
+		write_lock(&dev->domain_lock);
 		ret = vduse_dev_reg_umem(dev, umem.iova,
 					 umem.uaddr, umem.size);
-		mutex_unlock(&dev->domain_lock);
+		write_unlock(&dev->domain_lock);
 		break;
 	}
 	case VDUSE_IOTLB_DEREG_UMEM: {
@@ -1363,10 +1364,10 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 		if (!is_mem_zero((const char *)umem.reserved,
 				 sizeof(umem.reserved)))
 			break;
-		mutex_lock(&dev->domain_lock);
+		write_lock(&dev->domain_lock);
 		ret = vduse_dev_dereg_umem(dev, umem.iova,
 					   umem.size);
-		mutex_unlock(&dev->domain_lock);
+		write_unlock(&dev->domain_lock);
 		break;
 	}
 	case VDUSE_IOTLB_GET_INFO: {
@@ -1385,9 +1386,9 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 				 sizeof(info.reserved)))
 			break;
 
-		mutex_lock(&dev->domain_lock);
+		read_lock(&dev->domain_lock);
 		if (!dev->domain) {
-			mutex_unlock(&dev->domain_lock);
+			read_unlock(&dev->domain_lock);
 			break;
 		}
 		spin_lock(&dev->domain->iotlb_lock);
@@ -1402,7 +1403,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 				info.capability |= VDUSE_IOVA_CAP_UMEM;
 		}
 		spin_unlock(&dev->domain->iotlb_lock);
-		mutex_unlock(&dev->domain_lock);
+		read_unlock(&dev->domain_lock);
 		if (!map)
 			break;
 
@@ -1425,10 +1426,10 @@ static int vduse_dev_release(struct inode *inode, struct file *file)
 {
 	struct vduse_dev *dev = file->private_data;
 
-	mutex_lock(&dev->domain_lock);
+	write_lock(&dev->domain_lock);
 	if (dev->domain)
 		vduse_dev_dereg_umem(dev, 0, dev->domain->bounce_size);
-	mutex_unlock(&dev->domain_lock);
+	write_unlock(&dev->domain_lock);
 	spin_lock(&dev->msg_lock);
 	/* Make sure the inflight messages can processed after reconncection */
 	list_splice_init(&dev->recv_list, &dev->send_list);
@@ -1647,7 +1648,7 @@ static struct vduse_dev *vduse_dev_create(void)
 
 	mutex_init(&dev->lock);
 	mutex_init(&dev->mem_lock);
-	mutex_init(&dev->domain_lock);
+	rwlock_init(&dev->domain_lock);
 	spin_lock_init(&dev->msg_lock);
 	INIT_LIST_HEAD(&dev->send_list);
 	INIT_LIST_HEAD(&dev->recv_list);
@@ -1805,7 +1806,7 @@ static ssize_t bounce_size_store(struct device *device,
 	int ret;
 
 	ret = -EPERM;
-	mutex_lock(&dev->domain_lock);
+	write_lock(&dev->domain_lock);
 	if (dev->domain)
 		goto unlock;
 
@@ -1821,7 +1822,7 @@ static ssize_t bounce_size_store(struct device *device,
 	dev->bounce_size = bounce_size & PAGE_MASK;
 	ret = count;
 unlock:
-	mutex_unlock(&dev->domain_lock);
+	write_unlock(&dev->domain_lock);
 	return ret;
 }
 
@@ -2045,11 +2046,11 @@ static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 	if (ret)
 		return ret;
 
-	mutex_lock(&dev->domain_lock);
+	write_lock(&dev->domain_lock);
 	if (!dev->domain)
 		dev->domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
 						  dev->bounce_size);
-	mutex_unlock(&dev->domain_lock);
+	write_unlock(&dev->domain_lock);
 	if (!dev->domain) {
 		put_device(&dev->vdev->vdpa.dev);
 		return -ENOMEM;
@@ -2059,10 +2060,10 @@ static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 	ret = _vdpa_register_device(&dev->vdev->vdpa, dev->vq_num);
 	if (ret) {
 		put_device(&dev->vdev->vdpa.dev);
-		mutex_lock(&dev->domain_lock);
+		write_lock(&dev->domain_lock);
 		vduse_domain_destroy(dev->domain);
 		dev->domain = NULL;
-		mutex_unlock(&dev->domain_lock);
+		write_unlock(&dev->domain_lock);
 		return ret;
 	}
 
-- 
2.51.0