Am 26.10.21 um 13:52 schrieb guangming.cao@mediatek.com:

From: Guangming Cao Guangming.Cao@mediatek.com

On Tue, 2021-10-26 at 13:18 +0200, Christian König wrote:

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Am 14.10.21 um 12:25 schrieb guangming.cao@mediatek.com:

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From: Guangming Cao Guangming.Cao@mediatek.com

In this patch(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork....), it add a new IOCTL to support dma-buf user to set debug name.

But it also added a limitation of this IOCTL, it needs the attachments of dmabuf should be empty, otherwise it will fail.

For the original series, the idea was that allowing name change mid-use could confuse the users about the dma-buf. However, the rest of the series also makes sure each dma-buf have a unique inode(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork....), and any accounting should probably use that, without relying on the name as much.

So, removing this restriction will let dma-buf userspace users to use it more comfortably and without any side effect.

Signed-off-by: Guangming Cao Guangming.Cao@mediatek.com

We could now cleanup the return value from dma_buf_set_name() into a void since that function can't fail any more as far as I can see.

But that isn't mandatory I think, patch is Reviewed-by: Christian König christian.koenig@amd.com

So, here is no need to check return value of 'strndup_user', just return without error code if the almost impossible error occurs?

Good point, totally missed that one.

In that case I'm going to push the patch to drm-misc-next as is.

Regards, Christian.

Guangming.

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Regards, Christian.

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---

drivers/dma-buf/dma-buf.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 511fe0d217a0..5fbb3a2068a3 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 support changing the name of the dma-buf if the same
• • 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 @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) static long dma_buf_set_name(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);
• 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;

• return 0; } static long dma_buf_ioctl(struct file *file,