[PATCH sched_ext/for-7.1] tools/sched_ext: Add compat handling for sub-scheduler ops

[PATCH sched_ext/for-7.1] tools/sched_ext: Add compat handling for sub-scheduler ops

[Andrea Righi]

Extend SCX_OPS_OPEN() with compatibility handling for ops.sub_attach()
and ops.sub_detach(), allowing scx C schedulers with sub-scheduler
support to run on kernels both with and without its support.

Fixes: ebeca1f930ea ("sched_ext: Introduce cgroup sub-sched support")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
---
 tools/sched_ext/include/scx/compat.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/sched_ext/include/scx/compat.h b/tools/sched_ext/include/scx/compat.h
index 9e0c8f3161e87..5a1a08d22f3ad 100644
--- a/tools/sched_ext/include/scx/compat.h
+++ b/tools/sched_ext/include/scx/compat.h
@@ -160,6 +160,7 @@ static inline long scx_hotplug_seq(void)
  * COMPAT:
  * - v6.17: ops.cgroup_set_bandwidth()
  * - v6.19: ops.cgroup_set_idle()
+ * - v7.1:  ops.sub_attach(), ops.sub_detach()
  */
 #define SCX_OPS_OPEN(__ops_name, __scx_name) ({					\
 	struct __scx_name *__skel;						\
@@ -181,6 +182,16 @@ static inline long scx_hotplug_seq(void)
 		fprintf(stderr, "WARNING: kernel doesn't support ops.cgroup_set_idle()\n"); \
 		__skel->struct_ops.__ops_name->cgroup_set_idle = NULL;	\
 	}									\
+	if (__skel->struct_ops.__ops_name->sub_attach &&			\
+	    !__COMPAT_struct_has_field("sched_ext_ops", "sub_attach")) {	\
+		fprintf(stderr, "WARNING: kernel doesn't support ops.sub_attach()\n"); \
+		__skel->struct_ops.__ops_name->sub_attach = NULL;		\
+	}									\
+	if (__skel->struct_ops.__ops_name->sub_detach &&			\
+	    !__COMPAT_struct_has_field("sched_ext_ops", "sub_detach")) {	\
+		fprintf(stderr, "WARNING: kernel doesn't support ops.sub_detach()\n"); \
+		__skel->struct_ops.__ops_name->sub_detach = NULL;		\
+	}									\
 	__skel; 								\
 })
 
-- 
2.53.0

Re: [PATCH sched_ext/for-7.1] tools/sched_ext: Add compat handling for sub-scheduler ops

[Cheng-Yang Chou]

Hi Andrea,

On Sat, Mar 21, 2026 at 11:20:36AM +0100, Andrea Righi wrote:
> + * - v7.1:  ops.sub_attach(), ops.sub_detach()

Do we also want to handle sub_cgroup_id in this compat block for older
kernels?

>   */
>  #define SCX_OPS_OPEN(__ops_name, __scx_name) ({					\
>  	struct __scx_name *__skel;						\
> @@ -181,6 +182,16 @@ static inline long scx_hotplug_seq(void)
>  		fprintf(stderr, "WARNING: kernel doesn't support ops.cgroup_set_idle()\n"); \
>  		__skel->struct_ops.__ops_name->cgroup_set_idle = NULL;	\
>  	}									\
> +	if (__skel->struct_ops.__ops_name->sub_attach &&			\
> +	    !__COMPAT_struct_has_field("sched_ext_ops", "sub_attach")) {	\
> +		fprintf(stderr, "WARNING: kernel doesn't support ops.sub_attach()\n"); \
> +		__skel->struct_ops.__ops_name->sub_attach = NULL;		\
> +	}									\
> +	if (__skel->struct_ops.__ops_name->sub_detach &&			\
> +	    !__COMPAT_struct_has_field("sched_ext_ops", "sub_detach")) {	\
> +		fprintf(stderr, "WARNING: kernel doesn't support ops.sub_detach()\n"); \
> +		__skel->struct_ops.__ops_name->sub_detach = NULL;		\
> +	}									\
>  	__skel; 								\
>  })
>  
> -- 
> 2.53.0
> 

Overall looks good.

-- 
Thanks,
Cheng-Yang