From 98868668367b24487c0b0b3298d7ca98409baf07 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 12 Mar 2020 17:21:28 -0700 Subject: [PATCH] bpf: Abstract away entire bpf_link clean up procedure 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 Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200313002128.2028680-1-andriin@fb.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 - kernel/bpf/syscall.c | 18 +++++++++++------- 2 files changed, 11 insertions(+), 8 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 4ec8353..c2f815e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -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); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index b2f73ec..85567a6 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -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; } -- 2.7.4