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>
---
include/linux/bpf.h | 17 +++++++++++++++++
include/linux/btf.h | 2 ++
kernel/bpf/btf.c | 13 ++++---------
3 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3ace0d6227e3..fcb4ecd9d1fd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2294,6 +2294,14 @@ 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))
@@ -2303,6 +2311,15 @@ 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/include/linux/btf.h b/include/linux/btf.h
index 4214e76c9168..69159e649675 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -4,6 +4,7 @@
#ifndef _LINUX_BTF_H
#define _LINUX_BTF_H 1
+#include <linux/file.h>
#include <linux/types.h>
#include <linux/bpfptr.h>
#include <linux/bsearch.h>
@@ -143,6 +144,7 @@ void btf_get(struct btf *btf);
void btf_put(struct btf *btf);
const struct btf_header *btf_header(const struct btf *btf);
int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz);
+
struct btf *btf_get_by_fd(int fd);
int btf_get_info_by_fd(const struct btf *btf,
const union bpf_attr *attr,
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index e7a59e6462a9..ad5310fa1d3b 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7743,17 +7743,12 @@ int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
struct btf *btf_get_by_fd(int fd)
{
- struct btf *btf;
CLASS(fd, f)(fd);
+ struct btf *btf;
- 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
