[bug report] bpf, sockmap: convert to generic sk_msg interface

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Daniel Borkmann,

This is a semi-automatic email about new static checker warnings.

The patch 604326b41a6f: "bpf, sockmap: convert to generic sk_msg
interface" from Oct 13, 2018, leads to the following Smatch complaint:

    net/core/skmsg.c:792 sk_psock_write_space()
    error: we previously assumed 'psock' could be null (see line 790)

net/core/skmsg.c
   789		psock = sk_psock(sk);
   790		if (likely(psock && sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)))
                           ^^^^^
Check for NULL

   791			schedule_work(&psock->work);
   792		write_space = psock->saved_write_space;
                              ^^^^^^^^^^^^^^^^^^^^^^^^

   793		rcu_read_unlock();
   794		write_space(sk);
                ^^^^^^^^^^^^^^
The warning is on the wrong line.  The dereference is really here.

regards,
dan carpenter