[ Upstream commit
174974d8463b77c2b4065e98513adb204e64de7d ]
If the previous thing cat'ing $debugfs/rd left the FIFO full, then
subsequent open could deadlock in rd_write() (because open is blocked,
not giving a chance for read() to consume any data in the FIFO). Also
it is generally a good idea to clear out old data from the FIFO.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/496706/
Link: https://lore.kernel.org/r/20220807160901.2353471-2-robdclark@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>