Re: [PATCH tb-next] thunderbolt: stream: unmap buffers with mapped size

[Mika Westerberg]

Hi,

On Thu, Jun 11, 2026 at 02:45:30PM +0800, raoxu wrote:
> From: Xu Rao <raoxu@xxxxxxxxxxxxx>
> 
> The size passed to dma_unmap_page() must match the size used for the
> corresponding dma_map_page() call.
> 
> Stream RX and TX buffers are mapped with TB_MAX_FRAME_SIZE when the
> buffer pools are allocated. However, tbstream_ring_free() currently uses
> tb_ring_frame_size() as the unmap size.
> 
> That helper returns the current frame payload size, not the DMA mapping
> size. On the TX path, tbstream_dev_alloc_tx() stores a shorter payload
> length in frame.size when the payload is smaller than TB_MAX_FRAME_SIZE.
> This happens for a short final DATA frame, and also for the CLOSE frame,
> which is allocated with SZ_256.
> 
> In those cases the buffer was mapped with TB_MAX_FRAME_SIZE, but
> tb_ring_frame_size() returns the shorter frame payload length. This makes
> the dma_unmap_page() size differ from the original dma_map_page() size.
> 
> Use TB_MAX_FRAME_SIZE when unmapping stream buffers so the unmap size
> matches the DMA mapping size used by the buffer allocation paths.
> 
> Signed-off-by: Xu Rao <raoxu@xxxxxxxxxxxxx>

Applied to thunderbolt.git/fixes, thanks!