[PATCH bpf-next] selftests/bpf: Fix gcc -Wreturn-type error in the tail call subprog test

[PATCH bpf-next] selftests/bpf: Fix gcc -Wreturn-type error in the tail call subprog test

[Daniel Borkmann]

gcc's C front end warns for a static function returning non-void that has
no return statement at all, regardless of the for (;;) {} it ends in, and
BPF CI builds test_progs-bpf_gcc with -Werror:

  progs/verifier_cfg.c: In function 'tail_call_or_throw_subprog':
  error: no return statement in function returning non-void [-Werror=return-type]

Add an unreachable return after the loop.

  # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_cfg
  [...]
  #626/21  verifier_cfg/tail call in a subprogram without an exit:OK
  #626     verifier_cfg:OK
  Summary: 1/21 PASSED, 0 SKIPPED, 0/0 FAILED

Fixes: 5add2c64f474 ("selftests/bpf: Add a test for a tail call in a subprogram without an exit")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 tools/testing/selftests/bpf/progs/verifier_cfg.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_cfg.c b/tools/testing/selftests/bpf/progs/verifier_cfg.c
index 07388a922e5b..6379dfc9389b 100644
--- a/tools/testing/selftests/bpf/progs/verifier_cfg.c
+++ b/tools/testing/selftests/bpf/progs/verifier_cfg.c
@@ -196,6 +196,7 @@ static int tail_call_or_throw_subprog(void *ctx)
 	bpf_tail_call(ctx, &map_array, idx);
 	bpf_throw(0);
 	for (;;) {}
+	return 0;
 }
 
 SEC("tc")
-- 
2.43.0

Re: [PATCH bpf-next] selftests/bpf: Fix gcc -Wreturn-type error in the tail call subprog test

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Kumar Kartikeya Dwivedi <memxor@gmail.com>:

On Sat, 26 Sep 2026 13:38:35 +0200 you wrote:
> gcc's C front end warns for a static function returning non-void that has
> no return statement at all, regardless of the for (;;) {} it ends in, and
> BPF CI builds test_progs-bpf_gcc with -Werror:
> 
>   progs/verifier_cfg.c: In function 'tail_call_or_throw_subprog':
>   error: no return statement in function returning non-void [-Werror=return-type]
> 
> [...]

Here is the summary with links:
  - [bpf-next] selftests/bpf: Fix gcc -Wreturn-type error in the tail call subprog test
    https://git.kernel.org/bpf/bpf-next/c/ea9358e1270a

You are awesome, thank you!
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