diff options
| author | Tejun Heo <tj@kernel.org> | 2025-10-29 08:35:25 -1000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-10-29 10:41:21 -1000 |
| commit | 34423456443c5cf5ad5180155f7d40f96b836194 (patch) | |
| tree | 37fe308f7656a086a9633e168bef27c348e22515 /tools/sched_ext/include/scx/compat.h | |
| parent | a3f5d48222532484c1e85ef27cc6893803e4cd17 (diff) | |
sched_ext/tools: Restore backward compat with v6.12 kernels
Commit 111a79800aed ("tools/sched_ext: Strip compatibility macros for
cgroup and dispatch APIs") removed the compat layer for v6.12-v6.13 kfunc
renaming, but v6.12 is the current LTS kernel and will remain supported
through 2026. Restore backward compatibility so schedulers built with v6.19+
headers can run on v6.12 kernels.
The restored compat differs from the original in two ways:
1. Uses ___new/___old suffixes instead of ___compat for clarity. The new
macros check for v6.13+ names (scx_bpf_dsq_move*), fall back to v6.12
names (scx_bpf_dispatch_from_dsq*, scx_bpf_consume), then return safe
no-ops for missing symbols.
2. Integrates with the args-struct-packing changes added in c0d630ba347c
("sched_ext: Wrap kfunc args in struct to prepare for aux__prog").
scx_bpf_dsq_insert_vtime() now tries __scx_bpf_dsq_insert_vtime (args
struct), then scx_bpf_dsq_insert_vtime___compat (v6.13-v6.18), then
scx_bpf_dispatch_vtime___compat (pre-v6.13).
Forward compatibility is not restored - binaries built against v6.13 or
earlier headers won't run on v6.19+ kernels, as the old kfunc names are not
exported. This is acceptable since the priority is new binaries running on
older kernels.
Also add missing compat checks for ops.cgroup_set_bandwidth() (added v6.17)
and ops.cgroup_set_idle() (added v6.19). These need to be NULLed out in
userspace on older kernels.
Reported-by: Andrea Righi <arighi@nvidia.com>
Acked-and-tested-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'tools/sched_ext/include/scx/compat.h')
| -rw-r--r-- | tools/sched_ext/include/scx/compat.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/tools/sched_ext/include/scx/compat.h b/tools/sched_ext/include/scx/compat.h index 35c67c5174ac..8b4897fc8b99 100644 --- a/tools/sched_ext/include/scx/compat.h +++ b/tools/sched_ext/include/scx/compat.h @@ -151,6 +151,10 @@ static inline long scx_hotplug_seq(void) * * ec7e3b0463e1 ("implement-ops") in https://github.com/sched-ext/sched_ext is * the current minimum required kernel version. + * + * COMPAT: + * - v6.17: ops.cgroup_set_bandwidth() + * - v6.19: ops.cgroup_set_idle() */ #define SCX_OPS_OPEN(__ops_name, __scx_name) ({ \ struct __scx_name *__skel; \ @@ -162,6 +166,16 @@ static inline long scx_hotplug_seq(void) SCX_BUG_ON(!__skel, "Could not open " #__scx_name); \ __skel->struct_ops.__ops_name->hotplug_seq = scx_hotplug_seq(); \ SCX_ENUM_INIT(__skel); \ + if (__skel->struct_ops.__ops_name->cgroup_set_bandwidth && \ + !__COMPAT_struct_has_field("sched_ext_ops", "cgroup_set_bandwidth")) { \ + fprintf(stderr, "WARNING: kernel doesn't support ops.cgroup_set_bandwidth()\n"); \ + __skel->struct_ops.__ops_name->cgroup_set_bandwidth = NULL; \ + } \ + if (__skel->struct_ops.__ops_name->cgroup_set_idle && \ + !__COMPAT_struct_has_field("sched_ext_ops", "cgroup_set_idle")) { \ + fprintf(stderr, "WARNING: kernel doesn't support ops.cgroup_set_idle()\n"); \ + __skel->struct_ops.__ops_name->cgroup_set_idle = NULL; \ + } \ __skel; \ }) |