[ Upstream commit60be976ac4
] dev_hard_header() returns the length of the header, so we need to test for negative errors rather than non-zero. Fixes:889b7da23a
("mctp: Add initial routing framework") Signed-off-by: Matt Johnston <matt@codeconstruct.com.au> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>