Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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>
+90
-8
-6
tools/sched_ext/include/scx/common.bpf.h
-6
tools/sched_ext/include/scx/common.bpf.h
···
65
65
bool __scx_bpf_dsq_insert_vtime(struct task_struct *p, struct scx_bpf_dsq_insert_vtime_args *args) __ksym __weak;
66
66
u32 scx_bpf_dispatch_nr_slots(void) __ksym;
67
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void scx_bpf_dispatch_cancel(void) __ksym;
68
-
bool scx_bpf_dsq_move_to_local(u64 dsq_id) __ksym __weak;
69
-
void scx_bpf_dsq_move_set_slice(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
70
-
void scx_bpf_dsq_move_set_vtime(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
71
-
bool scx_bpf_dsq_move(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
72
-
bool scx_bpf_dsq_move_vtime(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
73
68
void scx_bpf_kick_cpu(s32 cpu, u64 flags) __ksym;
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s32 scx_bpf_dsq_nr_queued(u64 dsq_id) __ksym;
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void scx_bpf_destroy_dsq(u64 dsq_id) __ksym;
···
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struct rq *scx_bpf_cpu_rq(s32 cpu) __ksym;
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struct rq *scx_bpf_locked_rq(void) __ksym;
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struct task_struct *scx_bpf_cpu_curr(s32 cpu) __ksym __weak;
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-
struct cgroup *scx_bpf_task_cgroup(struct task_struct *p) __ksym __weak;
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u64 scx_bpf_now(void) __ksym __weak;
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void scx_bpf_events(struct scx_event_stats *events, size_t events__sz) __ksym __weak;
105
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+76
-2
tools/sched_ext/include/scx/compat.bpf.h
+76
-2
tools/sched_ext/include/scx/compat.bpf.h
···
15
15
__ret; \
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})
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+
/* v6.12: 819513666966 ("sched_ext: Add cgroup support") */
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+
struct cgroup *scx_bpf_task_cgroup___new(struct task_struct *p) __ksym __weak;
20
+
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+
#define scx_bpf_task_cgroup(p) \
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+
(bpf_ksym_exists(scx_bpf_task_cgroup___new) ? \
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+
scx_bpf_task_cgroup___new((p)) : NULL)
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+
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+
/*
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* v6.13: The verb `dispatch` was too overloaded and confusing. kfuncs are
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+
* renamed to unload the verb.
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*
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* scx_bpf_dispatch_from_dsq() and friends were added during v6.12 by
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* 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()").
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+
*/
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+
bool scx_bpf_dsq_move_to_local___new(u64 dsq_id) __ksym __weak;
33
+
void scx_bpf_dsq_move_set_slice___new(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
34
+
void scx_bpf_dsq_move_set_vtime___new(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
35
+
bool scx_bpf_dsq_move___new(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
36
+
bool scx_bpf_dsq_move_vtime___new(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
37
+
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+
bool scx_bpf_consume___old(u64 dsq_id) __ksym __weak;
39
+
void scx_bpf_dispatch_from_dsq_set_slice___old(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
40
+
void scx_bpf_dispatch_from_dsq_set_vtime___old(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
41
+
bool scx_bpf_dispatch_from_dsq___old(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
42
+
bool scx_bpf_dispatch_vtime_from_dsq___old(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
43
+
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+
#define scx_bpf_dsq_move_to_local(dsq_id) \
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+
(bpf_ksym_exists(scx_bpf_dsq_move_to_local___new) ? \
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+
scx_bpf_dsq_move_to_local___new((dsq_id)) : \
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+
scx_bpf_consume___old((dsq_id)))
48
+
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+
#define scx_bpf_dsq_move_set_slice(it__iter, slice) \
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+
(bpf_ksym_exists(scx_bpf_dsq_move_set_slice___new) ? \
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+
scx_bpf_dsq_move_set_slice___new((it__iter), (slice)) : \
52
+
(bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice___old) ? \
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+
scx_bpf_dispatch_from_dsq_set_slice___old((it__iter), (slice)) : \
54
+
(void)0))
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+
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+
#define scx_bpf_dsq_move_set_vtime(it__iter, vtime) \
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+
(bpf_ksym_exists(scx_bpf_dsq_move_set_vtime___new) ? \
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+
scx_bpf_dsq_move_set_vtime___new((it__iter), (vtime)) : \
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+
(bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime___old) ? \
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+
scx_bpf_dispatch_from_dsq_set_vtime___old((it__iter), (vtime)) : \
61
+
(void)0))
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+
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+
#define scx_bpf_dsq_move(it__iter, p, dsq_id, enq_flags) \
64
+
(bpf_ksym_exists(scx_bpf_dsq_move___new) ? \
65
+
scx_bpf_dsq_move___new((it__iter), (p), (dsq_id), (enq_flags)) : \
66
+
(bpf_ksym_exists(scx_bpf_dispatch_from_dsq___old) ? \
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+
scx_bpf_dispatch_from_dsq___old((it__iter), (p), (dsq_id), (enq_flags)) : \
68
+
false))
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+
70
+
#define scx_bpf_dsq_move_vtime(it__iter, p, dsq_id, enq_flags) \
71
+
(bpf_ksym_exists(scx_bpf_dsq_move_vtime___new) ? \
72
+
scx_bpf_dsq_move_vtime___new((it__iter), (p), (dsq_id), (enq_flags)) : \
73
+
(bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq___old) ? \
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+
scx_bpf_dispatch_vtime_from_dsq___old((it__iter), (p), (dsq_id), (enq_flags)) : \
75
+
false))
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+
18
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/*
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* v6.15: 950ad93df2fc ("bpf: add kfunc for populating cpumask bits")
20
79
*
···
225
166
* replaced with variants that pack scalar arguments in a struct. Wrappers are
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167
* provided to maintain source compatibility.
227
168
*
169
+
* v6.13: scx_bpf_dsq_insert_vtime() renaming is also handled here. See the
170
+
* block on dispatch renaming above for more details.
171
+
*
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* The kernel will carry the compat variants until v6.23 to maintain binary
229
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* compatibility. After v6.23 release, remove the compat handling and move the
230
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* wrappers to common.bpf.h.
231
175
*/
232
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s32 scx_bpf_select_cpu_and___compat(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
233
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const struct cpumask *cpus_allowed, u64 flags) __ksym __weak;
178
+
void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
234
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void scx_bpf_dsq_insert_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
235
180
236
181
/**
···
290
227
};
291
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return __scx_bpf_dsq_insert_vtime(p, &args);
293
-
} else {
230
+
} else if (bpf_ksym_exists(scx_bpf_dsq_insert_vtime___compat)) {
294
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scx_bpf_dsq_insert_vtime___compat(p, dsq_id, slice, vtime,
295
232
enq_flags);
233
+
return true;
234
+
} else {
235
+
scx_bpf_dispatch_vtime___compat(p, dsq_id, slice, vtime,
236
+
enq_flags);
296
237
return true;
297
238
}
298
239
}
···
306
239
* scx_bpf_dsq_insert() decl to common.bpf.h and drop compat helper after v6.22.
307
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* The extra ___compat suffix is to work around libbpf not ignoring __SUFFIX on
308
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* kernel side. The entire suffix can be dropped later.
242
+
*
243
+
* v6.13: scx_bpf_dsq_insert() renaming is also handled here. See the block on
244
+
* dispatch renaming above for more details.
309
245
*/
310
246
bool scx_bpf_dsq_insert___v2___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
311
247
void scx_bpf_dsq_insert___v1(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
248
+
void scx_bpf_dispatch___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
312
249
313
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static inline bool
314
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scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags)
315
252
{
316
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if (bpf_ksym_exists(scx_bpf_dsq_insert___v2___compat)) {
317
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return scx_bpf_dsq_insert___v2___compat(p, dsq_id, slice, enq_flags);
318
-
} else {
255
+
} else if (bpf_ksym_exists(scx_bpf_dsq_insert___v1)) {
319
256
scx_bpf_dsq_insert___v1(p, dsq_id, slice, enq_flags);
257
+
return true;
258
+
} else {
259
+
scx_bpf_dispatch___compat(p, dsq_id, slice, enq_flags);
320
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return true;
321
261
}
322
262
}
+14
tools/sched_ext/include/scx/compat.h
+14
tools/sched_ext/include/scx/compat.h
···
151
151
*
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* ec7e3b0463e1 ("implement-ops") in https://github.com/sched-ext/sched_ext is
153
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* the current minimum required kernel version.
154
+
*
155
+
* COMPAT:
156
+
* - v6.17: ops.cgroup_set_bandwidth()
157
+
* - v6.19: ops.cgroup_set_idle()
154
158
*/
155
159
#define SCX_OPS_OPEN(__ops_name, __scx_name) ({ \
156
160
struct __scx_name *__skel; \
···
166
162
SCX_BUG_ON(!__skel, "Could not open " #__scx_name); \
167
163
__skel->struct_ops.__ops_name->hotplug_seq = scx_hotplug_seq(); \
168
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SCX_ENUM_INIT(__skel); \
165
+
if (__skel->struct_ops.__ops_name->cgroup_set_bandwidth && \
166
+
!__COMPAT_struct_has_field("sched_ext_ops", "cgroup_set_bandwidth")) { \
167
+
fprintf(stderr, "WARNING: kernel doesn't support ops.cgroup_set_bandwidth()\n"); \
168
+
__skel->struct_ops.__ops_name->cgroup_set_bandwidth = NULL; \
169
+
} \
170
+
if (__skel->struct_ops.__ops_name->cgroup_set_idle && \
171
+
!__COMPAT_struct_has_field("sched_ext_ops", "cgroup_set_idle")) { \
172
+
fprintf(stderr, "WARNING: kernel doesn't support ops.cgroup_set_idle()\n"); \
173
+
__skel->struct_ops.__ops_name->cgroup_set_idle = NULL; \
174
+
} \
169
175
__skel; \
170
176
})
171
177