Add a new helper to get a pointer to a struct btf from a file
descriptor. This helper doesn't increase a refcnt. Add a comment
explaining this and pointing to a corresponding function which
does take a reference.
Signed-off-by: Anton Protopopov <aspsk@xxxxxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
include/linux/bpf.h | 17 +++++++++++++++++
kernel/bpf/btf.c | 11 +++--------
2 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index eaee2a819f4c..ac44b857b2f9 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2301,6 +2301,14 @@ void __bpf_obj_drop_impl(void *p, const struct btf_record *rec, bool percpu);
struct bpf_map *bpf_map_get(u32 ufd);
struct bpf_map *bpf_map_get_with_uref(u32 ufd);
+/*
+ * The __bpf_map_get() and __btf_get_by_fd() functions parse a file
+ * descriptor and return a corresponding map or btf object.
+ * Their names are double underscored to emphasize the fact that they
+ * do not increase refcnt. To also increase refcnt use corresponding
+ * bpf_map_get() and btf_get_by_fd() functions.
+ */
+
static inline struct bpf_map *__bpf_map_get(struct fd f)
{
if (fd_empty(f))
@@ -2310,6 +2318,15 @@ static inline struct bpf_map *__bpf_map_get(struct fd f)
return fd_file(f)->private_data;
}
+static inline struct btf *__btf_get_by_fd(struct fd f)
+{
+ if (fd_empty(f))
+ return ERR_PTR(-EBADF);
+ if (unlikely(fd_file(f)->f_op != &btf_fops))
+ return ERR_PTR(-EINVAL);
+ return fd_file(f)->private_data;
+}
+
void bpf_map_inc(struct bpf_map *map);
void bpf_map_inc_with_uref(struct bpf_map *map);
struct bpf_map *__bpf_map_inc_not_zero(struct bpf_map *map, bool uref);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index e7a59e6462a9..2ef4fef71910 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7746,14 +7746,9 @@ struct btf *btf_get_by_fd(int fd)
struct btf *btf;
CLASS(fd, f)(fd);
- if (fd_empty(f))
- return ERR_PTR(-EBADF);
-
- if (fd_file(f)->f_op != &btf_fops)
- return ERR_PTR(-EINVAL);
-
- btf = fd_file(f)->private_data;
- refcount_inc(&btf->refcnt);
+ btf = __btf_get_by_fd(f);
+ if (!IS_ERR(btf))
+ refcount_inc(&btf->refcnt);
return btf;
}
--
2.34.1
