Hi all,

After merging the kspp-gustavo tree, today's linux-next build (x86_64
allmodconfig) failed like this:

In file included from include/linux/bpf_verifier.h:9,
                 from kernel/bpf/verifier.c:12:
kernel/bpf/verifier.c: In function 'jit_subprogs':
include/linux/filter.h:366:4: error: cast between incompatible function types from 'unsigned int (*)(const void *, const struct bpf_insn *)' to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12472:16: note: in expansion of macro 'BPF_CAST_CALL'
12472 |    insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) -
      |                ^~~~~~~~~~~~~
kernel/bpf/verifier.c: In function 'do_misc_fixups':
include/linux/filter.h:366:4: error: cast between incompatible function types from 'void * (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12953:17: note: in expansion of macro 'BPF_CAST_CALL'
12953 |     insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) -
      |                 ^~~~~~~~~~~~~
include/linux/filter.h:366:4: error: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *, void *, u64)' {aka 'int (* const)(struct bpf_map *, void *, void *, long long unsigned int)'} to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12957:17: note: in expansion of macro 'BPF_CAST_CALL'
12957 |     insn->imm = BPF_CAST_CALL(ops->map_update_elem) -
      |                 ^~~~~~~~~~~~~
include/linux/filter.h:366:4: error: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12961:17: note: in expansion of macro 'BPF_CAST_CALL'
12961 |     insn->imm = BPF_CAST_CALL(ops->map_delete_elem) -
      |                 ^~~~~~~~~~~~~
include/linux/filter.h:366:4: error: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *, u64)' {aka 'int (* const)(struct bpf_map *, void *, long long unsigned int)'} to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12965:17: note: in expansion of macro 'BPF_CAST_CALL'
12965 |     insn->imm = BPF_CAST_CALL(ops->map_push_elem) -
      |                 ^~~~~~~~~~~~~
include/linux/filter.h:366:4: error: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12969:17: note: in expansion of macro 'BPF_CAST_CALL'
12969 |     insn->imm = BPF_CAST_CALL(ops->map_pop_elem) -
      |                 ^~~~~~~~~~~~~
include/linux/filter.h:366:4: error: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12973:17: note: in expansion of macro 'BPF_CAST_CALL'
12973 |     insn->imm = BPF_CAST_CALL(ops->map_peek_elem) -
      |                 ^~~~~~~~~~~~~
include/linux/filter.h:366:4: error: cast between incompatible function types from 'int (* const)(struct bpf_map *, u32,  u64)' {aka 'int (* const)(struct bpf_map *, unsigned int,  long long unsigned int)'} to 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} [-Werror=cast-function-type]
  366 |   ((u64 (*)(u64, u64, u64, u64, u64))(x))
      |    ^
kernel/bpf/verifier.c:12977:17: note: in expansion of macro 'BPF_CAST_CALL'
12977 |     insn->imm = BPF_CAST_CALL(ops->map_redirect) -
      |                 ^~~~~~~~~~~~~
cc1: all warnings being treated as errors

Caused by commit

  ffea83dd8823 ("Makefile: Enable -Wcast-function-type")

I have reverted that commit for today.

-- 
Cheers,
Stephen Rothwell