Re: dm: impose configurable deadline for dm_request_fn's merge heuristic

Re: dm: impose configurable deadline for dm_request_fn's merge heuristic

[Dan Carpenter]

Hello Mike Snitzer,

The patch 6ee47d96b97d: "dm: impose configurable deadline for
dm_request_fn's merge heuristic" from Feb 26, 2015, leads to the
following static checker warning:

	drivers/md/dm.c:1968 dm_attr_rq_based_queue_deadline_store()
	warn: impossible condition '(deadline > ((~0 >> 1))) => (s32min-s32max > s32max)'

drivers/md/dm.c
  1959  ssize_t dm_attr_rq_based_queue_deadline_store(struct mapped_device *md,
  1960                                                const char *buf, size_t count)
  1961  {
  1962          int err, deadline;
  1963  
  1964          if (!dm_request_based(md))
  1965                  return count;
  1966  
  1967          err = kstrtoint(buf, 10, &deadline);
  1968          if (err || deadline > INT_MAX)
                           ^^^^^^^^^^^^^^^^^^
Impossible condition.  But it might not hurt to test for negative
deadlines?

  1969                  return -EINVAL;
  1970  
  1971          if (!deadline)
  1972                  deadline = DEF_QUEUE_DEADLINE;
  1973          else if (deadline > MAX_QUEUE_DEADLINE)
  1974                  deadline = MAX_QUEUE_DEADLINE;
  1975  
  1976          atomic_set(&md->rq_based_queue_deadline, deadline);
  1977  
  1978          return count;
  1979  }

regards,
dan carpenter

Re: dm: impose configurable deadline for dm_request_fn's merge heuristic

[Mike Snitzer]

On Mon, Mar 02 2015 at 11:31am -0500,
Dan Carpenter <dan.carpenter@oracle.com> wrote:

> Hello Mike Snitzer,
> 
> The patch 6ee47d96b97d: "dm: impose configurable deadline for
> dm_request_fn's merge heuristic" from Feb 26, 2015, leads to the
> following static checker warning:
> 
> 	drivers/md/dm.c:1968 dm_attr_rq_based_queue_deadline_store()
> 	warn: impossible condition '(deadline > ((~0 >> 1))) => (s32min-s32max > s32max)'

Fixed up with latest code, see:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=f975bc0d522d1e57b108bf9e2e0293ee3f78f821