linux/tools/sched_ext/include/scx/compat.bpf.h
Tejun Heo 5cbb302880 sched_ext: Rename scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()
In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patch performs the third set of renames. Compatibility is maintained
by:

- The previous kfunc names are still provided by the kernel so that old
  binaries can run. Kernel generates a warning when the old names are used.

- compat.bpf.h provides wrappers for the new names which automatically fall
  back to the old names when running on older kernels. They also trigger
  build error if old names are used for new builds.

- scx_bpf_dispatch[_vtime]_from_dsq*() were already wrapped in __COMPAT
  macros as they were introduced during v6.12 cycle. Wrap new API in
  __COMPAT macros too and trigger build errors on both __COMPAT prefixed and
  naked usages of the old names.

The compat features will be dropped after v6.15.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Johannes Bechberger <me@mostlynerdless.de>
Acked-by: Giovanni Gherdovich <ggherdovich@suse.com>
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Ming Yang <yougmark94@gmail.com>
2024-11-11 07:06:16 -10:00

138 lines
6.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
* Copyright (c) 2024 Tejun Heo <tj@kernel.org>
* Copyright (c) 2024 David Vernet <dvernet@meta.com>
*/
#ifndef __SCX_COMPAT_BPF_H
#define __SCX_COMPAT_BPF_H
#define __COMPAT_ENUM_OR_ZERO(__type, __ent) \
({ \
__type __ret = 0; \
if (bpf_core_enum_value_exists(__type, __ent)) \
__ret = __ent; \
__ret; \
})
/* v6.12: 819513666966 ("sched_ext: Add cgroup support") */
#define __COMPAT_scx_bpf_task_cgroup(p) \
(bpf_ksym_exists(scx_bpf_task_cgroup) ? \
scx_bpf_task_cgroup((p)) : NULL)
/*
* v6.13: The verb `dispatch` was too overloaded and confusing. kfuncs are
* renamed to unload the verb.
*
* Build error is triggered if old names are used. New binaries work with both
* new and old names. The compat macros will be removed on v6.15 release.
*
* scx_bpf_dispatch_from_dsq() and friends were added during v6.12 by
* 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()").
* Preserve __COMPAT macros until v6.15.
*/
void scx_bpf_dispatch___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
bool scx_bpf_consume___compat(u64 dsq_id) __ksym __weak;
void scx_bpf_dispatch_from_dsq_set_slice___compat(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
void scx_bpf_dispatch_from_dsq_set_vtime___compat(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
bool scx_bpf_dispatch_from_dsq___compat(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
bool scx_bpf_dispatch_vtime_from_dsq___compat(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
#define scx_bpf_dsq_insert(p, dsq_id, slice, enq_flags) \
(bpf_ksym_exists(scx_bpf_dsq_insert) ? \
scx_bpf_dsq_insert((p), (dsq_id), (slice), (enq_flags)) : \
scx_bpf_dispatch___compat((p), (dsq_id), (slice), (enq_flags)))
#define scx_bpf_dsq_insert_vtime(p, dsq_id, slice, vtime, enq_flags) \
(bpf_ksym_exists(scx_bpf_dsq_insert_vtime) ? \
scx_bpf_dsq_insert_vtime((p), (dsq_id), (slice), (vtime), (enq_flags)) : \
scx_bpf_dispatch_vtime___compat((p), (dsq_id), (slice), (vtime), (enq_flags)))
#define scx_bpf_dsq_move_to_local(dsq_id) \
(bpf_ksym_exists(scx_bpf_dsq_move_to_local) ? \
scx_bpf_dsq_move_to_local((dsq_id)) : \
scx_bpf_consume___compat((dsq_id)))
#define __COMPAT_scx_bpf_dsq_move_set_slice(it__iter, slice) \
(bpf_ksym_exists(scx_bpf_dsq_move_set_slice) ? \
scx_bpf_dsq_move_set_slice((it__iter), (slice)) : \
(bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice___compat) ? \
scx_bpf_dispatch_from_dsq_set_slice___compat((it__iter), (slice)) : \
(void)0))
#define __COMPAT_scx_bpf_dsq_move_set_vtime(it__iter, vtime) \
(bpf_ksym_exists(scx_bpf_dsq_move_set_vtime) ? \
scx_bpf_dsq_move_set_vtime((it__iter), (vtime)) : \
(bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime___compat) ? \
scx_bpf_dispatch_from_dsq_set_vtime___compat((it__iter), (vtime)) : \
(void) 0))
#define __COMPAT_scx_bpf_dsq_move(it__iter, p, dsq_id, enq_flags) \
(bpf_ksym_exists(scx_bpf_dsq_move) ? \
scx_bpf_dsq_move((it__iter), (p), (dsq_id), (enq_flags)) : \
(bpf_ksym_exists(scx_bpf_dispatch_from_dsq___compat) ? \
scx_bpf_dispatch_from_dsq___compat((it__iter), (p), (dsq_id), (enq_flags)) : \
false))
#define __COMPAT_scx_bpf_dsq_move_vtime(it__iter, p, dsq_id, enq_flags) \
(bpf_ksym_exists(scx_bpf_dsq_move_vtime) ? \
scx_bpf_dsq_move_vtime((it__iter), (p), (dsq_id), (enq_flags)) : \
(bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq___compat) ? \
scx_bpf_dispatch_vtime_from_dsq___compat((it__iter), (p), (dsq_id), (enq_flags)) : \
false))
#define scx_bpf_dispatch(p, dsq_id, slice, enq_flags) \
_Static_assert(false, "scx_bpf_dispatch() renamed to scx_bpf_dsq_insert()")
#define scx_bpf_dispatch_vtime(p, dsq_id, slice, vtime, enq_flags) \
_Static_assert(false, "scx_bpf_dispatch_vtime() renamed to scx_bpf_dsq_insert_vtime()")
#define scx_bpf_consume(dsq_id) ({ \
_Static_assert(false, "scx_bpf_consume() renamed to scx_bpf_dsq_move_to_local()"); \
false; \
})
#define scx_bpf_dispatch_from_dsq_set_slice(it__iter, slice) \
_Static_assert(false, "scx_bpf_dispatch_from_dsq_set_slice() renamed to scx_bpf_dsq_move_set_slice()")
#define scx_bpf_dispatch_from_dsq_set_vtime(it__iter, vtime) \
_Static_assert(false, "scx_bpf_dispatch_from_dsq_set_vtime() renamed to scx_bpf_dsq_move_set_vtime()")
#define scx_bpf_dispatch_from_dsq(it__iter, p, dsq_id, enq_flags) ({ \
_Static_assert(false, "scx_bpf_dispatch_from_dsq() renamed to scx_bpf_dsq_move()"); \
false; \
})
#define scx_bpf_dispatch_vtime_from_dsq(it__iter, p, dsq_id, enq_flags) ({ \
_Static_assert(false, "scx_bpf_dispatch_vtime_from_dsq() renamed to scx_bpf_dsq_move_vtime()"); \
false; \
})
#define __COMPAT_scx_bpf_dispatch_from_dsq_set_slice(it__iter, slice) \
_Static_assert(false, "__COMPAT_scx_bpf_dispatch_from_dsq_set_slice() renamed to __COMPAT_scx_bpf_dsq_move_set_slice()")
#define __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(it__iter, vtime) \
_Static_assert(false, "__COMPAT_scx_bpf_dispatch_from_dsq_set_vtime() renamed to __COMPAT_scx_bpf_dsq_move_set_vtime()")
#define __COMPAT_scx_bpf_dispatch_from_dsq(it__iter, p, dsq_id, enq_flags) ({ \
_Static_assert(false, "__COMPAT_scx_bpf_dispatch_from_dsq() renamed to __COMPAT_scx_bpf_dsq_move()"); \
false; \
})
#define __COMPAT_scx_bpf_dispatch_vtime_from_dsq(it__iter, p, dsq_id, enq_flags) ({ \
_Static_assert(false, "__COMPAT_scx_bpf_dispatch_vtime_from_dsq() renamed to __COMPAT_scx_bpf_dsq_move_vtime()"); \
false; \
})
/*
* Define sched_ext_ops. This may be expanded to define multiple variants for
* backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().
*/
#define SCX_OPS_DEFINE(__name, ...) \
SEC(".struct_ops.link") \
struct sched_ext_ops __name = { \
__VA_ARGS__, \
};
#endif /* __SCX_COMPAT_BPF_H */