linux-kernel - [RFC PATCH bpf-next v2 0/5] bpf, sched_ext: Make kfunc filters support struct

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Message-ID:
 <AM6PR03MB5080855B90C3FE9B6C4243B099FE2@AM6PR03MB5080.eurprd03.prod.outlook.com>
Date: Fri, 14 Feb 2025 20:03:50 +0000
From: Juntong Deng <juntong.deng@...look.com>
To: ast@...nel.org,
	daniel@...earbox.net,
	john.fastabend@...il.com,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
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Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH bpf-next v2 0/5] bpf, sched_ext: Make kfunc filters support struct_ops context to reduce runtime overhead

This patch series makes kfunc filters support the use of struct_ops
context information to reduce SCX runtime overhead.

After improving kfunc filters, SCX no longer needs the mask-based
runtime kfuncs call restriction, so this patch removes the mask-based
runtime restriction and updates the corresponding test case.

I added *st_ops as part of the context information to avoid kfuncs being
incorrectly blocked when used in non-SCX scenarios where the member
offsets would have a different meaning (not sure if this is necessary).

This patch series version uses a completely new design in filtering.

Use scx_ops_context_flags to declare context-sensitive SCX kfuncs that
can be used by each SCX operation, no longer need to compare moff
in filters.

Use scx_kfunc_ids_ops_context to implement unified filtering context-
sensitive SCX kfuncs, using different kfunc id sets for grouping
purposes and filtering purposes, no longer need to add multiple filters.

This is still an RFC patch series.

If I got something wrong please let me know.

Signed-off-by: Juntong Deng <juntong.deng@...look.com>
---
v1 -> v2:
* Use completely new design in filtering

* v1 link: https://lore.kernel.org/bpf/AM6PR03MB5080261D024B49D26F3FFF0099F72@AM6PR03MB5080.eurprd03.prod.outlook.com/T/#t

Juntong Deng (5):
  bpf: Add struct_ops context information to struct bpf_prog_aux
  sched_ext: Declare context-sensitive kfunc groups that can be used by
    different SCX operations
  sched_ext: Add scx_kfunc_ids_ops_context for unified filtering of
    context-sensitive SCX kfuncs
  sched_ext: Removed mask-based runtime restrictions on calling kfuncs
    in different contexts
  selftests/sched_ext: Update enq_select_cpu_fails to adapt to
    struct_ops context filter

 include/linux/bpf.h                           |   2 +
 include/linux/sched/ext.h                     |  24 --
 kernel/bpf/verifier.c                         |   8 +-
 kernel/sched/ext.c                            | 395 ++++++++----------
 .../sched_ext/enq_select_cpu_fails.c          |  35 +-
 5 files changed, 190 insertions(+), 274 deletions(-)

-- 
2.39.5