Kuniyuki Iwashima wrote:
When __skb_try_recv_datagram() returns NULL in __unix_dgram_recvmsg(),
we hold unix_state_lock() unconditionally.
This is because SOCK_SEQPACKET sk needs to return EOF in case its peer
has been close()d concurrently.
This behaviour totally depends on the timing of the peer's close() and
reading sk->sk_shutdown, and taking the lock does not play a role.
Let's drop the lock from __unix_dgram_recvmsg() and use READ_ONCE().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>