[ Upstream commit f140ad9f ]

READ_ONCE should be used when reading rings prior to accessing the
statistics pointer. Introduce this as well as the corresponding WRITE_ONCE
usage when allocating and freeing the rings, to ensure protected access.
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>