2021-07-14 12:31:37

by guangming.cao

Subject: [PATCH] dma-buf: support users to change dma_buf.name

From: Guangming Cao <[email protected]>

User space user can call DMA_BUF_SET_NAME to set dma_buf.name,
also add a kernel api for users to do same thing at kernel side.

Signed-off-by: Guangming Cao <[email protected]>
---
drivers/dma-buf/dma-buf.c | 28 ++++++++++++++++++++++------
include/linux/dma-buf.h | 1 +
2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..949af232c644 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -331,20 +331,20 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
* purpose between different devices.
*
* @dmabuf: [in] dmabuf buffer that will be renamed.
- * @buf: [in] A piece of userspace memory that contains the name of
+ * @buf: [in] A piece of memory that contains the name of
* the dma-buf.
*
* Returns 0 on success. If the dma-buf buffer is already attached to
* devices, return -EBUSY.
*
*/
-static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
+long dma_buf_set_name(struct dma_buf *dmabuf, const char *buf)
{
- char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
+ char *name = kstrndup(buf, DMA_BUF_NAME_LEN, GFP_KERNEL);
long ret = 0;

- if (IS_ERR(name))
- return PTR_ERR(name);
+ if (!name)
+ return -ENOMEM;

dma_resv_lock(dmabuf->resv, NULL);
if (!list_empty(&dmabuf->attachments)) {
@@ -361,6 +361,22 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
dma_resv_unlock(dmabuf->resv);
return ret;
}
+EXPORT_SYMBOL_GPL(dma_buf_set_name);
+
+static long
+dma_buf_set_name_user(struct dma_buf *dmabuf, const char __user *buf)
+{
+ char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
+ long ret = 0;
+
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
+ ret = dma_buf_set_name(dmabuf, name);
+ kfree(name);
+
+ return ret;
+}

static long dma_buf_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
@@ -403,7 +419,7 @@ static long dma_buf_ioctl(struct file *file,

case DMA_BUF_SET_NAME_A:
case DMA_BUF_SET_NAME_B:
- return dma_buf_set_name(dmabuf, (const char __user *)arg);
+ return dma_buf_set_name_user(dmabuf, (const char __user *)arg);

default:
return -ENOTTY;
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index efdc56b9d95f..e6612ab59a59 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
unsigned long);
int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
+long dma_buf_set_name(struct dma_buf *dmabuf, const char *name);
#endif /* __DMA_BUF_H__ */
--
2.17.1

2021-07-14 12:36:23

by Christian König

Subject: Re: [PATCH] dma-buf: support users to change dma_buf.name

Am 14.07.21 um 14:29 schrieb [email protected]:
> From: Guangming Cao <[email protected]>
>
> User space user can call DMA_BUF_SET_NAME to set dma_buf.name,
> also add a kernel api for users to do same thing at kernel side.

Well if you want to add a kernel API to set the name you also need to
provide an user for this.

Christian.

>
> Signed-off-by: Guangming Cao <[email protected]>
> ---
> drivers/dma-buf/dma-buf.c | 28 ++++++++++++++++++++++------
> include/linux/dma-buf.h | 1 +
> 2 files changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 511fe0d217a0..949af232c644 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -331,20 +331,20 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
> * purpose between different devices.
> *
> * @dmabuf: [in] dmabuf buffer that will be renamed.
> - * @buf: [in] A piece of userspace memory that contains the name of
> + * @buf: [in] A piece of memory that contains the name of
> * the dma-buf.
> *
> * Returns 0 on success. If the dma-buf buffer is already attached to
> * devices, return -EBUSY.
> *
> */
> -static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
> +long dma_buf_set_name(struct dma_buf *dmabuf, const char *buf)
> {
> - char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
> + char *name = kstrndup(buf, DMA_BUF_NAME_LEN, GFP_KERNEL);
> long ret = 0;
>
> - if (IS_ERR(name))
> - return PTR_ERR(name);
> + if (!name)
> + return -ENOMEM;
>
> dma_resv_lock(dmabuf->resv, NULL);
> if (!list_empty(&dmabuf->attachments)) {
> @@ -361,6 +361,22 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
> dma_resv_unlock(dmabuf->resv);
> return ret;
> }
> +EXPORT_SYMBOL_GPL(dma_buf_set_name);
> +
> +static long
> +dma_buf_set_name_user(struct dma_buf *dmabuf, const char __user *buf)
> +{
> + char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
> + long ret = 0;
> +
> + if (IS_ERR(name))
> + return PTR_ERR(name);
> +
> + ret = dma_buf_set_name(dmabuf, name);
> + kfree(name);
> +
> + return ret;
> +}
>
> static long dma_buf_ioctl(struct file *file,
> unsigned int cmd, unsigned long arg)
> @@ -403,7 +419,7 @@ static long dma_buf_ioctl(struct file *file,
>
> case DMA_BUF_SET_NAME_A:
> case DMA_BUF_SET_NAME_B:
> - return dma_buf_set_name(dmabuf, (const char __user *)arg);
> + return dma_buf_set_name_user(dmabuf, (const char __user *)arg);
>
> default:
> return -ENOTTY;
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index efdc56b9d95f..e6612ab59a59 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
> unsigned long);
> int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
> void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
> +long dma_buf_set_name(struct dma_buf *dmabuf, const char *name);
> #endif /* __DMA_BUF_H__ */