Re: [patch V2 21/37] rseq: Make exit debugging static branch based

[Mathieu Desnoyers]

On 2025-08-23 12:39, Thomas Gleixner wrote:
> Disconnect it from the config switch and use the static debug branch. This
> is a temporary measure for validating the rework. At the end this check
> needs to be hidden behind lockdep as it has nothing to do with the other
> debug infrastructure, which mainly aids user space debugging by enabling a
> zoo of checks which terminate misbehaving tasks instead of letting them
> keep the hard to diagnose pieces.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>

> ---
>   include/linux/rseq_entry.h |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/include/linux/rseq_entry.h
> +++ b/include/linux/rseq_entry.h
> @@ -275,7 +275,7 @@ static __always_inline void rseq_exit_to
>   
>   	rseq_stat_inc(rseq_stats.exit);
>   
> -	if (IS_ENABLED(CONFIG_DEBUG_RSEQ))
> +	if (static_branch_unlikely(&rseq_debug_enabled))
>   		WARN_ON_ONCE(ev->sched_switch);
>   
>   	/*


--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com