[RFC PATCH 3/4] rpmsg: apu_rpmsg: update the way to store IOMMU mapping

[Alexandre Bailon]

In order to reduce the memory mapping operations we are going to
add an IOCTL to request a mapping.
To make easier to add this new operation, use 2 lists to store the
mappings, one for the request and one for the device.

Signed-off-by: Alexandre Bailon <abailon@xxxxxxxxxxxx>
---
 drivers/rpmsg/apu_rpmsg.c | 104 +++++++++++++++++++++++++-------------
 1 file changed, 70 insertions(+), 34 deletions(-)

diff --git a/drivers/rpmsg/apu_rpmsg.c b/drivers/rpmsg/apu_rpmsg.c
index e14597c467d7..343bd08a859a 100644
--- a/drivers/rpmsg/apu_rpmsg.c
+++ b/drivers/rpmsg/apu_rpmsg.c
@@ -38,12 +38,14 @@ struct rpmsg_apu {
 	u8 available_response;
 	spinlock_t ctx_lock;
 	struct list_head requests;
+
+	struct list_head buffers;
 };
 
 struct rpmsg_request {
 	u8 ready;
 	struct list_head node;
-	struct apu_buffer *buffer;
+	struct list_head buffers;
 	void *req;
 };
 
@@ -53,6 +55,11 @@ struct apu_buffer {
 	struct dma_buf_attachment *attachment;
 	struct sg_table *sg_table;
 	u32 iova;
+
+	struct rpmsg_apu *apu;
+	struct list_head node;
+	struct list_head req_node;
+	struct kref refcount;
 };
 
 /*
@@ -106,23 +113,46 @@ static int apu_rpmsg_callback(struct rpmsg_device *rpdev, void *data, int count,
 	return 0;
 }
 
-static int apu_device_memory_map(struct rpmsg_apu *apu,
-				 struct apu_buffer *buffer)
+static struct apu_buffer *apu_device_memory_map(struct rpmsg_apu *apu,
+		uint32_t fd, struct rpmsg_request *rpmsg_req)
 {
 	struct rpmsg_device *rpdev = apu->rpdev;
+	struct apu_buffer *buffer;
 	phys_addr_t phys;
 	int total_buf_space;
 	int iova_pfn;
 	int ret;
 
-	if (!buffer->fd)
-		return 0;
+	if (!fd)
+		return NULL;
+
+	list_for_each_entry(buffer, &apu->buffers, node) {
+		if (buffer->fd == fd) {
+			kref_get(&buffer->refcount);
+			if (rpmsg_req)
+				list_add(&buffer->req_node,
+					 &rpmsg_req->buffers);
+
+			return buffer;
+		}
+	}
+
+	buffer = kmalloc(sizeof(*buffer), GFP_KERNEL);
+	if (!buffer)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&buffer->refcount);
+	buffer->fd = fd;
+	buffer->apu = apu;
+	INIT_LIST_HEAD(&buffer->req_node);
+	INIT_LIST_HEAD(&buffer->node);
 
 	buffer->dma_buf = dma_buf_get(buffer->fd);
 	if (IS_ERR(buffer->dma_buf)) {
 		dev_err(&rpdev->dev, "Failed to get dma_buf from fd: %ld\n",
 			PTR_ERR(buffer->dma_buf));
-		return PTR_ERR(buffer->dma_buf);
+		ret = PTR_ERR(buffer->dma_buf);
+		goto err_free_buffer;
 	}
 
 	buffer->attachment = dma_buf_attach(buffer->dma_buf, &rpdev->dev);
@@ -158,7 +188,9 @@ static int apu_device_memory_map(struct rpmsg_apu *apu,
 		goto err_free_iova;
 	}
 
-	return 0;
+	list_add(&buffer->node, &apu->buffers);
+
+	return buffer;
 
 err_free_iova:
 	free_iova(apu->iovad, iova_pfn);
@@ -170,13 +202,17 @@ static int apu_device_memory_map(struct rpmsg_apu *apu,
 	dma_buf_detach(buffer->dma_buf, buffer->attachment);
 err_dma_buf_put:
 	dma_buf_put(buffer->dma_buf);
+err_free_buffer:
+	kfree(buffer);
 
-	return ret;
+	return ERR_PTR(ret);
 }
 
-static void apu_device_memory_unmap(struct rpmsg_apu *apu,
-				    struct apu_buffer *buffer)
+static void apu_device_memory_unmap(struct kref *ref)
 {
+	struct apu_buffer *buffer = container_of(ref, struct apu_buffer,
+						 refcount);
+	struct rpmsg_apu *apu = buffer->apu;
 	int total_buf_space;
 
 	if (!buffer->fd)
@@ -190,6 +226,8 @@ static void apu_device_memory_unmap(struct rpmsg_apu *apu,
 				 DMA_BIDIRECTIONAL);
 	dma_buf_detach(buffer->dma_buf, buffer->attachment);
 	dma_buf_put(buffer->dma_buf);
+	list_del(&buffer->node);
+	kfree(buffer);
 }
 
 static int apu_send_request(struct rpmsg_apu *apu,
@@ -198,7 +236,7 @@ static int apu_send_request(struct rpmsg_apu *apu,
 	int ret;
 	struct rpmsg_device *rpdev = apu->rpdev;
 	struct apu_dev_request *dev_req;
-	struct apu_buffer *buffer;
+	struct apu_buffer *buffer, *tmp;
 	struct rpmsg_request *rpmsg_req;
 	unsigned long flags;
 
@@ -222,14 +260,21 @@ static int apu_send_request(struct rpmsg_apu *apu,
 	dev_req_buffer_size = (u32 *)(dev_req_da + dev_req->count);
 	memcpy(dev_req->data, req->data, req->size_in);
 
-	buffer = kmalloc_array(req->count, sizeof(*buffer), GFP_KERNEL);
+	rpmsg_req = kzalloc(sizeof(*rpmsg_req), GFP_KERNEL);
+	if (!rpmsg_req)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&rpmsg_req->buffers);
 	for (i = 0; i < req->count; i++) {
-		buffer[i].fd = fd[i];
-		ret = apu_device_memory_map(apu, &buffer[i]);
-		if (ret)
+		buffer = apu_device_memory_map(apu, fd[i], rpmsg_req);
+		if (IS_ERR(buffer)) {
+			ret = PTR_ERR(buffer);
 			goto err_free_memory;
-		dev_req_da[i] = buffer[i].iova;
+		}
+
+		dev_req_da[i] = buffer->iova;
 		dev_req_buffer_size[i] = buffer_size[i];
+		list_add(&buffer->req_node, &rpmsg_req->buffers);
 	}
 
 	ret = ida_simple_get(&req_ida, 0, 0xffff, GFP_KERNEL);
@@ -238,15 +283,8 @@ static int apu_send_request(struct rpmsg_apu *apu,
 
 	dev_req->id = ret;
 
-	rpmsg_req = kzalloc(sizeof(*rpmsg_req), GFP_KERNEL);
-	if (!rpmsg_req) {
-		ret =  -ENOMEM;
-		goto err_ida_remove;
-	}
-
 	req->id = dev_req->id;
 	rpmsg_req->req = req;
-	rpmsg_req->buffer = buffer;
 	spin_lock_irqsave(&apu->ctx_lock, flags);
 	list_add(&rpmsg_req->node, &apu->requests);
 	spin_unlock_irqrestore(&apu->ctx_lock, flags);
@@ -261,15 +299,12 @@ static int apu_send_request(struct rpmsg_apu *apu,
 
 err:
 	list_del(&rpmsg_req->node);
-	kfree(rpmsg_req);
 	kfree(req);
-err_ida_remove:
 	ida_simple_remove(&req_ida, dev_req->id);
 err_free_memory:
-	for (i--; i >= 0; i--)
-		apu_device_memory_unmap(apu, &buffer[i]);
-
-	kfree(buffer);
+	list_for_each_entry_safe(buffer, tmp, &rpmsg_req->buffers, req_node)
+		kref_put(&buffer->refcount, apu_device_memory_unmap);
+	kfree(rpmsg_req);
 	kfree(dev_req);
 
 	return ret;
@@ -296,12 +331,12 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
 	struct rpmsg_apu *apu = fp->private_data;
 	struct apu_request apu_req;
 	struct apu_request *apu_req_full;
+	struct apu_buffer *buffer, *tmp;
 	void __user *argp = (void __user *)arg;
 	int len;
 	int ret;
 	unsigned long flags;
 	struct rpmsg_request *rpmsg_req;
-	int i;
 
 	ret = 0;
 
@@ -370,11 +405,11 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
 					ret = -EFAULT;
 				apu->available_response--;
 				ida_simple_remove(&req_ida, req->id);
-				for (i = 0; i < req->count ; i++)
-					apu_device_memory_unmap(apu,
-							&rpmsg_req->buffer[i]);
+				list_for_each_entry_safe(buffer, tmp, &rpmsg_req->buffers, req_node) {
+					kref_put(&buffer->refcount, apu_device_memory_unmap);
+					list_del(&buffer->req_node);
+				}
 				list_del(&rpmsg_req->node);
-				kfree(rpmsg_req->buffer);
 				kfree(rpmsg_req->req);
 				kfree(rpmsg_req);
 				break;
@@ -554,6 +589,7 @@ static int apu_rpmsg_probe(struct rpmsg_device *rpdev)
 	if (!apu)
 		return -ENOMEM;
 	apu->rpdev = rpdev;
+	INIT_LIST_HEAD(&apu->buffers);
 
 	apu->rproc = apu_get_rproc(rpdev);
 	if (IS_ERR_OR_NULL(apu->rproc))
-- 
2.26.2