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bpf: Abstract away entire bpf_link clean up procedure

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Instead of requiring users to do three steps for cleaning up bpf_link, its
anon_inode file, and unused fd, abstract that away into bpf_link_cleanup()
helper. bpf_link_defunct() is removed, as it shouldn't be needed as an
individual operation anymore.

v1->v2:
- keep bpf_link_cleanup() static for now (Daniel).

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200313002128.2028680-1-andriin@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2020-03-12 17:21:28 -07:00 committed by Alexei Starovoitov
parent 4cd729fa02
commit 9886866836
2 changed files with 11 additions and 8 deletions
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1
include/linux/bpf.h
View file

@ -1075,7 +1075,6 @@ struct bpf_link_ops {
void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops,
struct bpf_prog *prog);
void bpf_link_defunct(struct bpf_link *link);
void bpf_link_inc(struct bpf_link *link);
void bpf_link_put(struct bpf_link *link);
int bpf_link_new_fd(struct bpf_link *link);

18
kernel/bpf/syscall.c
View file

@ -2188,9 +2188,17 @@ void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops,
link->prog = prog;
}
void bpf_link_defunct(struct bpf_link *link)
/* Clean up bpf_link and corresponding anon_inode file and FD. After
* anon_inode is created, bpf_link can't be just kfree()'d due to deferred
* anon_inode's release() call. This helper manages marking bpf_link as
* defunct, releases anon_inode file and puts reserved FD.
*/
static void bpf_link_cleanup(struct bpf_link *link, struct file *link_file,
int link_fd)
{
link->prog = NULL;
fput(link_file);
put_unused_fd(link_fd);
}
void bpf_link_inc(struct bpf_link *link)
@ -2383,9 +2391,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog)
err = bpf_trampoline_link_prog(prog);
if (err) {
bpf_link_defunct(&link->link);
fput(link_file);
put_unused_fd(link_fd);
bpf_link_cleanup(&link->link, link_file, link_fd);
goto out_put_prog;
}
@ -2498,9 +2504,7 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
err = bpf_probe_register(link->btp, prog);
if (err) {
bpf_link_defunct(&link->link);
fput(link_file);
put_unused_fd(link_fd);
bpf_link_cleanup(&link->link, link_file, link_fd);
goto out_put_btp;
}