Re: [PATCH bpf-next v4 12/18] bpf: Reject stack arguments if tail call reachable

Yonghong Song
2026-04-13T16:38:05Z

On 4/11/26 10:43 PM, bot+bpf-ci@kernel.org wrote:
>> Tailcalls are been deprecated. So reject stack arguments
>> if tail call is in the way.
> The commit message has a grammar issue ("are been" should probably
> be "have been" or "are being"), but more importantly, is the claim
> that tail calls are deprecated accurate?
>
> Looking at the mailing list discussion on the v1 series, Alexei's
> guidance was "let's disallow mixing 6+ args and tailcalls" due to
> stack frame layout incompatibility, not because tail calls are being
> deprecated.
>
> Could the commit message more precisely describe the actual
> reason for the restriction? Something along the lines of "tail
> calls and stack arguments require incompatible stack frame
> handling" would better explain to future readers why the
> combination is rejected.

Okay. Will update the commit message.

>
>
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
>
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/24299298635