From: Corbin McElhanney Date: Wed, 9 Aug 2017 10:30:28 -0400 Subject: drm/amd/display: Add comment explaining context free Git-commit: e771aae02baa59386972faec491cd221c169ed53 Patch-mainline: v4.15-rc1 References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166 This comment explains a previous change that adds some complexity to the context free in dc: commit 9ad58779a895 ("drm/amd/display: Fix accessing freed memory") Signed-off-by: Corbin McElhanney Reviewed-by: Tony Cheng Acked-by: Harry Wentland Signed-off-by: Alex Deucher Acked-by: Petr Tesarik --- drivers/gpu/drm/amd/display/dc/core/dc.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/gpu/drm/amd/display/dc/core/dc.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c @@ -1740,6 +1740,15 @@ void dc_update_planes_and_stream(struct } if (core_dc->current_context != context) { + + /* Since memory free requires elevated IRQL, an interrupt + * request is generated by mem free. If this happens + * between freeing and reassigning the context, our vsync + * interrupt will call into dc and cause a memory + * corruption BSOD. Hence, we first reassign the context, + * then free the old context. + */ + struct validate_context *old = core_dc->current_context; core_dc->current_context = context;