Add inclusion of linux/errno.h as otherwise the reference to EINVAL may be invalid. Fixes: f3cf4134c5c6 ("bpf: Add bpf_lookup_*_key() and bpf_key_put() kfuncs") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202308261414.HKw1Mrip-lkp@intel.com/ Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>