linux-kernel - [PATCH v2] bpf: Document cfi_stubs and owner fields in struct bpf_struct

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Message-ID: <20251120204620.59571-2-nirbhay.lkd@gmail.com>
Date: Fri, 21 Nov 2025 02:16:21 +0530
From: Nirbhay Sharma <nirbhay.lkd@...il.com>
To: ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org
Cc: martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org,
	skhan@...uxfoundation.org,
	david.hunter.linux@...il.com,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Nirbhay Sharma <nirbhay.lkd@...il.com>
Subject: [PATCH v2] bpf: Document cfi_stubs and owner fields in struct bpf_struct_ops

Add missing kernel-doc documentation for the cfi_stubs and owner
fields in struct bpf_struct_ops to fix the following warnings:

  Warning: include/linux/bpf.h:1931 struct member 'cfi_stubs' not
  described in 'bpf_struct_ops'
  Warning: include/linux/bpf.h:1931 struct member 'owner' not
  described in 'bpf_struct_ops'

The cfi_stubs field was added in commit 2cd3e3772e41 ("x86/cfi,bpf:
Fix bpf_struct_ops CFI") to provide CFI stub functions for trampolines,
and the owner field is used for module reference counting.

Signed-off-by: Nirbhay Sharma <nirbhay.lkd@...il.com>
---
Changes in v2:
- Removed documentation for non-existent fields (type, value_type, type_id,
  value_id) that were moved to bpf_struct_ops_desc in commit 4c5763ed996a

 include/linux/bpf.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d808253f2e94..96851fa0494f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1905,12 +1905,14 @@ struct btf_member;
  *	      reason, if this callback is not defined, the check is skipped as
  *	      the struct_ops map will have final verification performed in
  *	      @reg.
- * @type: BTF type.
- * @value_type: Value type.
+ * @cfi_stubs: Pointer to a structure of stub functions for CFI. These stubs
+ *	       provide the correct Control Flow Integrity hashes for the
+ *	       trampolines generated by BPF struct_ops.
+ * @owner: The module that owns this struct_ops. Used for module reference
+ *	   counting to ensure the module providing the struct_ops cannot be
+ *	   unloaded while in use.
  * @name: The name of the struct bpf_struct_ops object.
  * @func_models: Func models
- * @type_id: BTF type id.
- * @value_id: BTF value id.
  */
 struct bpf_struct_ops {
 	const struct bpf_verifier_ops *verifier_ops;
-- 
2.48.1