[ Upstream commit d09bc83640d524b8467a660db7b1d15e6562a1de ]

Simplify the ring buffer handling with the in-place API.

Also avoid the dynamic allocation and the memory leak in the channel
callback function.
Signed-off-by: NDexuan Cui <decui@microsoft.com>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>