On 10/8/21 7:47 PM, guangming.cao@xxxxxxxxxxxx wrote:
From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
If dma-buf don't want userspace users to touch the dmabuf buffer,
it seems we should add this restriction into dma_buf_ops.mmap,
not in this IOCTL:DMA_BUF_SET_NAME.
With this restriction, we can only know the kernel users of the dmabuf
by attachments.
However, for many userspace users, such as userpsace users of dma_heap,
they also need to mark the usage of dma-buf, and they don't care about
who attached to this dmabuf, and seems it's no meaning to waitting for
to be waiting for
IOCTL:DMA_BUF_SET_NAME rather than mmap.
Signed-off-by: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
---
drivers/dma-buf/dma-buf.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..afbd0a226639 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
/**
* dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
- * The name of the dma-buf buffer can only be set when the dma-buf is not
- * attached to any devices. It could theoritically support changing the
- * name of the dma-buf if the same piece of memory is used for multiple
- * purpose between different devices.
+ * It could theoritically support changing the name of the dma-buf if the same
theoretically
(yes, it was incorrect before this change.)
+ * piece of memory is used for multiple purpose between different devices.
*
* @dmabuf: [in] dmabuf buffer that will be renamed.
* @buf: [in] A piece of userspace memory that contains the name of
@@ -346,19 +344,11 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
if (IS_ERR(name))
return PTR_ERR(name);
- dma_resv_lock(dmabuf->resv, NULL);
- if (!list_empty(&dmabuf->attachments)) {
- ret = -EBUSY;
- kfree(name);
- goto out_unlock;
- }
spin_lock(&dmabuf->name_lock);
kfree(dmabuf->name);
dmabuf->name = name;
spin_unlock(&dmabuf->name_lock);
-out_unlock:
- dma_resv_unlock(dmabuf->resv);
return ret;
}
--
~Randy
