Re: [PATCH 2/2] sched_ext: scx_qmap: Read SCX_RESCUE_DISABLE through the enum lookup tables

[Andrea Righi]

On Thu, Oct 22, 2026 at 02:03:48PM -1000, Tejun Heo wrote:
> 788b494fab1c ("sched_ext: scx_qmap: Drop the compat code") left one compat
> lookup behind: the -B 0 case reads SCX_RESCUE_DISABLE with
> __COMPAT_ENUM_OR_ZERO(). Userspace can read SCX_RESCUE_DISABLE only from BTF
> as it is in the kernel-internal enum scx_consts. The enum lookup tables
> already read their entries from BTF for every scheduler at open time.
> 
> Add SCX_RESCUE_DISABLE to the lookup tables and read it from the skeleton's
> rodata. No behavior change.

And, as a reminder, we should add SCX_RESCUE_DISABLE to the scx repo as
well.

Reviewed-by: Andrea Righi <arighi@xxxxxxxxxx>

Thanks,
-Andrea

> 
> Suggested-by: Andrea Righi <arighi@xxxxxxxxxx>
> Link: https://lore.kernel.org/all/ataTuzRFTRm_pax6@gpd4/
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> ---
>  tools/sched_ext/include/scx/enums.autogen.bpf.h | 3 +++
>  tools/sched_ext/include/scx/enums.autogen.h     | 1 +
>  tools/sched_ext/scx_qmap.c                      | 2 +-
>  3 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/sched_ext/include/scx/enums.autogen.bpf.h b/tools/sched_ext/include/scx/enums.autogen.bpf.h
> index 405a3e6b8f33..d0c37018659e 100644
> --- a/tools/sched_ext/include/scx/enums.autogen.bpf.h
> +++ b/tools/sched_ext/include/scx/enums.autogen.bpf.h
> @@ -13,6 +13,9 @@ const volatile u64 __SCX_SLICE_DFL __weak;
>  const volatile u64 __SCX_SLICE_INF __weak;
>  #define SCX_SLICE_INF __SCX_SLICE_INF
>  
> +const volatile u64 __SCX_RESCUE_DISABLE __weak;
> +#define SCX_RESCUE_DISABLE __SCX_RESCUE_DISABLE
> +
>  const volatile u64 __SCX_RQ_ONLINE __weak;
>  #define SCX_RQ_ONLINE __SCX_RQ_ONLINE
>  
> diff --git a/tools/sched_ext/include/scx/enums.autogen.h b/tools/sched_ext/include/scx/enums.autogen.h
> index 7ec2e5e41cb2..c4a7260f0983 100644
> --- a/tools/sched_ext/include/scx/enums.autogen.h
> +++ b/tools/sched_ext/include/scx/enums.autogen.h
> @@ -9,6 +9,7 @@
>  	SCX_ENUM_SET(skel, scx_public_consts, SCX_OPS_NAME_LEN); \
>  	SCX_ENUM_SET(skel, scx_public_consts, SCX_SLICE_DFL); \
>  	SCX_ENUM_SET(skel, scx_public_consts, SCX_SLICE_INF); \
> +	SCX_ENUM_SET(skel, scx_consts, SCX_RESCUE_DISABLE); \
>  	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_ONLINE); \
>  	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_CAN_STOP_TICK); \
>  	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_BAL_PENDING); \
> diff --git a/tools/sched_ext/scx_qmap.c b/tools/sched_ext/scx_qmap.c
> index 9b1cbe187ebd..fe2f206f5c8a 100644
> --- a/tools/sched_ext/scx_qmap.c
> +++ b/tools/sched_ext/scx_qmap.c
> @@ -427,7 +427,7 @@ int main(int argc, char **argv)
>  			u32 ppt = strtoul(optarg, NULL, 0);
>  
>  			if (!ppt)
> -				ppt = __COMPAT_ENUM_OR_ZERO("scx_consts", "SCX_RESCUE_DISABLE");
> +				ppt = skel->rodata->__SCX_RESCUE_DISABLE;
>  			skel->struct_ops.qmap_ops->rescue_bandwidth_ppt = ppt;
>  			break;
>  		}
> -- 
> 2.56.0
> 
>