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 <abai...@baylibre.com>
---
 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

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