From 4e885fab7164689f031a6c73522a3d91674c5bdc Mon Sep 17 00:00:00 2001 From: Anton Protopopov Date: Fri, 13 Dec 2024 13:09:28 +0000 Subject: bpf: Add a __btf_get_by_fd helper 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 Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20241213130934.1087929-2-aspsk@isovalent.com --- include/linux/bpf.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'include/linux/bpf.h') 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); -- cgit v1.2.3