linux-kernel - [PATCH net v5 2/2] net: refactor bpf_sk_reuseport

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Date:   Fri,  5 Aug 2022 15:48:36 +0800
From:   Hawkins Jiawei <yin31149@...il.com>
To:     syzbot+5f26f85569bd179c18ce@...kaller.appspotmail.com,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>
Cc:     paskripkin@...il.com, skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        18801353760@....com, Hawkins Jiawei <yin31149@...il.com>,
        Jakub Kicinski <kuba@...nel.org>, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net v5 2/2] net: refactor bpf_sk_reuseport_detach()

Refactor sk_user_data dereference using more generic function
__rcu_dereference_sk_user_data_with_flags(), which improve its
maintainability

Suggested-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Hawkins Jiawei <yin31149@...il.com>
---
 kernel/bpf/reuseport_array.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c
index e2618fb5870e..85fa9dbfa8bf 100644
--- a/kernel/bpf/reuseport_array.c
+++ b/kernel/bpf/reuseport_array.c
@@ -21,14 +21,11 @@ static struct reuseport_array *reuseport_array(struct bpf_map *map)
 /* The caller must hold the reuseport_lock */
 void bpf_sk_reuseport_detach(struct sock *sk)
 {
-	uintptr_t sk_user_data;
+	struct sock __rcu **socks;
 
 	write_lock_bh(&sk->sk_callback_lock);
-	sk_user_data = (uintptr_t)sk->sk_user_data;
-	if (sk_user_data & SK_USER_DATA_BPF) {
-		struct sock __rcu **socks;
-
-		socks = (void *)(sk_user_data & SK_USER_DATA_PTRMASK);
+	socks = __rcu_dereference_sk_user_data_with_flags(sk, SK_USER_DATA_BPF);
+	if (socks) {
 		WRITE_ONCE(sk->sk_user_data, NULL);
 		/*
 		 * Do not move this NULL assignment outside of
-- 
2.25.1