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| author | Eric Dumazet <edumazet@google.com> | 2025-09-02 18:36:03 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-09-03 16:08:24 -0700 |
| commit | 5d6b58c932ec451a5c41482790eb5b1ecf165a94 (patch) | |
| tree | 6b905b072ff03439511c79cb7b186af8775b609c /net | |
| parent | b4ada0618eed0fbd1b1630f73deb048c592b06a1 (diff) | |
| download | linux-5d6b58c932ec451a5c41482790eb5b1ecf165a94.tar.gz linux-5d6b58c932ec451a5c41482790eb5b1ecf165a94.tar.bz2 linux-5d6b58c932ec451a5c41482790eb5b1ecf165a94.zip | |
net: lockless sock_i_ino()
Followup of commit c51da3f7a161 ("net: remove sock_i_uid()")
A recent syzbot report was the trigger for this change.
Over the years, we had many problems caused by the
read_lock[_bh](&sk->sk_callback_lock) in sock_i_uid().
We could fix smc_diag_dump_proto() or make a more radical move:
Instead of waiting for new syzbot reports, cache the socket
inode number in sk->sk_ino, so that we no longer
need to acquire sk->sk_callback_lock in sock_i_ino().
This makes socket dumps faster (one less cache line miss,
and two atomic ops avoided).
Prior art:
commit 25a9c8a4431c ("netlink: Add __sock_i_ino() for __netlink_diag_dump().")
commit 4f9bf2a2f5aa ("tcp: Don't acquire inet_listen_hashbucket::lock with disabled BH.")
commit efc3dbc37412 ("rds: Make rds_sock_lock BH rather than IRQ safe.")
Fixes: d2d6422f8bd1 ("x86: Allow to enable PREEMPT_RT.")
Reported-by: syzbot+50603c05bbdf4dfdaffa@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68b73804.050a0220.3db4df.01d8.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20250902183603.740428-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/sock.c | 22 | ||||
| -rw-r--r-- | net/mptcp/protocol.c | 1 | ||||
| -rw-r--r-- | net/netlink/diag.c | 2 |
3 files changed, 1 insertions, 24 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 7c26ec8dce63..158bddd23134 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2780,28 +2780,6 @@ void sock_pfree(struct sk_buff *skb) EXPORT_SYMBOL(sock_pfree); #endif /* CONFIG_INET */ -unsigned long __sock_i_ino(struct sock *sk) -{ - unsigned long ino; - - read_lock(&sk->sk_callback_lock); - ino = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_ino : 0; - read_unlock(&sk->sk_callback_lock); - return ino; -} -EXPORT_SYMBOL(__sock_i_ino); - -unsigned long sock_i_ino(struct sock *sk) -{ - unsigned long ino; - - local_bh_disable(); - ino = __sock_i_ino(sk); - local_bh_enable(); - return ino; -} -EXPORT_SYMBOL(sock_i_ino); - /* * Allocate a skb from the socket's send buffer. */ diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 9a287b75c1b3..e6fd97b21e9e 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3554,7 +3554,6 @@ void mptcp_sock_graft(struct sock *sk, struct socket *parent) write_lock_bh(&sk->sk_callback_lock); rcu_assign_pointer(sk->sk_wq, &parent->wq); sk_set_socket(sk, parent); - WRITE_ONCE(sk->sk_uid, SOCK_INODE(parent)->i_uid); write_unlock_bh(&sk->sk_callback_lock); } diff --git a/net/netlink/diag.c b/net/netlink/diag.c index 61981e01fd6f..b8e58132e8af 100644 --- a/net/netlink/diag.c +++ b/net/netlink/diag.c @@ -168,7 +168,7 @@ mc_list: NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, NLM_F_MULTI, - __sock_i_ino(sk)) < 0) { + sock_i_ino(sk)) < 0) { ret = 1; break; } |