af_unix: Move spin_lock() in manage_oob().
When OOB skb has been already consumed, manage_oob() returns the next
skb if exists. In such a case, we need to fall back to the else branch
below.
Then, we want to keep holding spin_lock(&sk->sk_receive_queue.lock).
Let's move it out of if-else branch and add lightweight check before
spin_lock() for major use cases without OOB skb.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240905193240.17565-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>