[PATCH] tracing/probes: Clarify btf_find_struct_member() container parameter and add kernel-doc
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2026-09-25 04:12:27
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Masami Hiramatsu (Google) <mhiramat@kernel.org> btf_find_struct_member() returns the containing structure or union type (which can be an inner anonymous struct/union rather than the outer passed type) via its last parameter. However, the parameter was named @member_type, which easily confuses readers and static analyzers into thinking it returns the member field's own datatype. Rename @member_type to @container_type in the prototype, definition, and callers to make the relationship explicit. Also convert the comment above btf_find_struct_member() to standard kernel-doc format, documenting all parameters and return values. Assisted-by: LLM Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- kernel/trace/trace_btf.c | 34 ++++++++++++++++++++++++---------- kernel/trace/trace_btf.h | 2 +- kernel/trace/trace_probe.c | 6 +++--- 3 files changed, 28 insertions(+), 14 deletions(-)
diff --git a/kernel/trace/trace_btf.c b/kernel/trace/trace_btf.c
index ee7a04886bf6..a534907336ff 100644
--- a/kernel/trace/trace_btf.c
+++ b/kernel/trace/trace_btf.c@@ -59,19 +59,33 @@ struct btf_anon_stack { u32 offset; }; -/* - * Find a member of data structure/union by name and return it. - * Return NULL if not found, or ERR_PTR(-EINVAL) if parameter is invalid. - * If the member is a member of an anonymous union/structure, the bit offset - * of that anonymous union/structure is stored into @anon_offset. - * If @member_type is non-NULL, the actual containing structure/union type - * of the found member is stored into @member_type. +/** + * btf_find_struct_member() - Find a member of data structure/union by name + * @btf: Pointer to BTF object. + * @type: Pointer to the struct/union BTF type to search within. + * @member_name: Name of the member to find. + * @anon_offset: Pointer to store bit offset of enclosing anonymous union/struct. + * @container_type: Pointer to store the actual containing struct/union type. + * + * Find a member of data structure/union by name, traversing into anonymous + * unions and structures if necessary. + * + * If the member is inside an anonymous union/structure, the bit offset + * of that anonymous union/structure from @type is stored into @anon_offset. + * If @container_type is non-NULL, the actual struct/union BTF type that + * directly contains the found member is stored into @container_type. + * + * Return: + * * Pointer to &struct btf_member on success. + * * %NULL if the member was not found. + * * %ERR_PTR(-EINVAL) if @type is not a struct/union. + * * %ERR_PTR(-ENOMEM) if memory allocation failed. */ const struct btf_member *btf_find_struct_member(struct btf *btf, const struct btf_type *type, const char *member_name, u32 *anon_offset, - const struct btf_type **member_type) + const struct btf_type **container_type) { struct btf_anon_stack *anon_stack; const struct btf_member *member;
@@ -103,8 +117,8 @@ const struct btf_member *btf_find_struct_member(struct btf *btf, if (name && !strcmp(member_name, name)) { if (anon_offset) *anon_offset = cur_offset; - if (member_type) - *member_type = type; + if (container_type) + *container_type = type; goto out; } }
diff --git a/kernel/trace/trace_btf.h b/kernel/trace/trace_btf.h
index 4bd26bceae23..68f1d61fefb0 100644
--- a/kernel/trace/trace_btf.h
+++ b/kernel/trace/trace_btf.h@@ -9,4 +9,4 @@ const struct btf_member *btf_find_struct_member(struct btf *btf, const struct btf_type *type, const char *member_name, u32 *anon_offset, - const struct btf_type **member_type); + const struct btf_type **container_type);
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 804442b2f7d2..17899ab15171 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c@@ -625,7 +625,7 @@ static int get_bitoffset_of_field(char **pfieldname, const struct btf_type **pty { const struct btf_type *type = *ptype; const struct btf_member *field; - const struct btf_type *mtype; + const struct btf_type *container_type; struct btf *btf = ctx_btf(ctx); char *fieldname = *pfieldname; int bitoffs = 0;
@@ -641,7 +641,7 @@ static int get_bitoffset_of_field(char **pfieldname, const struct btf_type **pty anon_offs = 0; field = btf_find_struct_member(btf, type, fieldname, - &anon_offs, &mtype); + &anon_offs, &container_type); if (IS_ERR(field)) { trace_probe_log_err(ctx->offset, BAD_BTF_TID); return PTR_ERR(field);
@@ -654,7 +654,7 @@ static int get_bitoffset_of_field(char **pfieldname, const struct btf_type **pty bitoffs += anon_offs; /* Accumulate the bit-offsets of the dot-connected fields */ - if (btf_type_kflag(mtype)) { + if (btf_type_kflag(container_type)) { bitoffs += BTF_MEMBER_BIT_OFFSET(field->offset); ctx->last_bitsize = BTF_MEMBER_BITFIELD_SIZE(field->offset); } else {