[bug report] block, bfq: bring forward seek&think time update

[Dan Carpenter]

Hello Paolo Valente,

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

The patch a3f9bce3697a: "block, bfq: bring forward seek&think time 
update" from Jun 25, 2019, leads to the following Smatch complaint:

    block/bfq-iosched.c:5353 __bfq_insert_request()
    warn: variable dereferenced before check 'bfqq' (see line 5349)

block/bfq-iosched.c
  5348  
  5349          bfq_update_io_thinktime(bfqd, bfqq);
                                              ^^^^
The patch introduces a new dereference (inside the function)

  5350          bfq_update_has_short_ttime(bfqd, bfqq, RQ_BIC(rq));
  5351          bfq_update_io_seektime(bfqd, bfqq, rq);
  5352  
  5353          waiting = bfqq && bfq_bfqq_wait_request(bfqq);
                          ^^^^
but the old code assumed "bfqq" could be NULL.

  5354          bfq_add_request(rq);
  5355          idle_timer_disabled = waiting && !bfq_bfqq_wait_request(bfqq);

regards,
dan carpenter