dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel()grafted

When dma_device_put() drops the last reference on chan->device->ref,
dma_device_release() runs and may free the dma_device along with its
channels.

dma_chan_put() then still reads chan->device->owner via
dma_chan_to_owner() for the trailing module_put(). KASAN catches it:

	slab-use-after-free in dma_chan_put+0x3e6/0x4c0
	Read of size 8 by task insmod/6319
	Freed by task 6319:
	  kfree+0x225/0x470
	  dma_chan_put+0x395/0x4c0
	  dmaengine_put+0xf8/0x160

Cache the module owner in dma_chan_put() before the put so the trailing
module_put() does not need chan->device.

Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct")
Suggested-by: Sashiko <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/Documentation/gpu/meson.rst b/Documentation/gpu/meson.rst
new file mode 100644
index 000000000..b9e2f9aa3
--- /dev/null
+++ b/Documentation/gpu/meson.rst
@@ -0,0 +1,55 @@
+=============================================
+drm/meson AmLogic Meson Video Processing Unit
+=============================================
+
+.. kernel-doc:: drivers/gpu/drm/meson/meson_drv.c
+   :doc: Video Processing Unit
+
+Video Processing Unit
+=====================
+
+The Amlogic Meson Display controller is composed of several components
+that are going to be documented below:
+
+.. code::
+
+  DMC|---------------VPU (Video Processing Unit)----------------|------HHI------|
+     | vd1   _______     _____________    _________________     |               |
+  D  |-------|      |----|            |   |                |    |   HDMI PLL    |
+  D  | vd2   | VIU  |    | Video Post |   | Video Encoders |<---|-----VCLK      |
+  R  |-------|      |----| Processing |   |                |    |               |
+     | osd2  |      |    |            |---| Enci ----------|----|-----VDAC------|
+  R  |-------| CSC  |----| Scalers    |   | Encp ----------|----|----HDMI-TX----|
+  A  | osd1  |      |    | Blenders   |   | Encl ----------|----|---------------|
+  M  |-------|______|----|____________|   |________________|    |               |
+  ___|__________________________________________________________|_______________|
+
+Video Input Unit
+================
+
+.. kernel-doc:: drivers/gpu/drm/meson/meson_viu.c
+   :doc: Video Input Unit
+
+Video Post Processing
+=====================
+
+.. kernel-doc:: drivers/gpu/drm/meson/meson_vpp.c
+   :doc: Video Post Processing
+
+Video Encoder
+=============
+
+.. kernel-doc:: drivers/gpu/drm/meson/meson_venc.c
+   :doc: Video Encoder
+
+Video Clocks
+============
+
+.. kernel-doc:: drivers/gpu/drm/meson/meson_vclk.c
+   :doc: Video Clocks
+
+HDMI Video Output
+=================
+
+.. kernel-doc:: drivers/gpu/drm/meson/meson_dw_hdmi.c
+   :doc: HDMI Output