Re: [PATCH v3] arm64: ptrace: don't warn on missing siginfo in a group-stop

[Oleg Nesterov <oleg@redhat.com>]

On 11/05, Zhao Gongyi wrote:
>
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -573,8 +573,8 @@ static void update_syscall_orig_x0_after_ptrace(struct task_struct *target)
>  	if (regs->syscallno == NO_SYSCALL)
>  		return;
>
> -	/* We should only be called when target is in a ptrace stop */
> -	if (WARN_ON_ONCE(!info))
> +	/* Non-seized group-stops do not provide siginfo (see do_jobctl_trap()). */
> +	if (!info)
>  		return;

First of all, FWIW

Acked-by: Oleg Nesterov <oleg@redhat.com>

This change is "obviously good" and doesn't change the current behaviour.



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But can't resist... The old comment was obviously wrong, the new one doesn't
look clear to me. It correctly explains why info can be NULL, but not why we
should not update orig_x0 in this case. May be it should just say that exit-stop
always comes with info != NULL?

Nevermind, I leave this to you, Catalin, and Will.

And I see another email from Will, I'll try to reply tomorrow.

In any case, let me repeat, the patch looks fine to me.

Oleg.