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b130dc7dc1
When closing the DRM device while a vblank is pending, we access file_priv after it has been free'd, which gives: Unable to handle kernel NULL pointer dereference at virtual address 00000000 ... PC is at __list_add+0x5c/0xe8 LR is at send_vblank_event+0x54/0x1f0 ... [<c02952e8>] (__list_add) from [<c031a7b4>] (send_vblank_event+0x54/0x1f0) [<c031a760>] (send_vblank_event) from [<c031a9c0>] (drm_send_vblank_event+0x70/0x78) [<c031a950>] (drm_send_vblank_event) from [<c031a9f8>] (drm_crtc_send_vblank_event+0x30/0x34) [<c031a9c8>] (drm_crtc_send_vblank_event) from [<c0339ad8>] (vop_isr+0x224/0x28c) [<c03398b4>] (vop_isr) from [<c0081780>] (handle_irq_event_percpu+0x12c/0x3e4) This can be triggered somewhat reliably with: modetest -M rockchip -v -s ... Add a preclose hook to the driver so that we can discard any pending vblank events when the device is closed. (am from https://patchwork.kernel.org/patch/8568111) Change-Id: Icce075cf22f3a9d7b2157c29a47b370160b0c8d8 Signed-off-by: John Keeping <john@metanate.com> Signed-off-by: Mark Yao <mark.yao@rock-chips.com>