Re: IB/mlx4: Build the port IBoE GID table properly under bonding

Dan Carpenter
2014-02-18T14:28:58Z

On Tue, Feb 18, 2014 at 04:13:28PM +0200, Moni Shoua wrote:
> On 2/17/2014 1:52 PM, Dan Carpenter wrote:
> >Hello Moni Shoua,
> >
> >This is a semi-automatic email about new static checker warnings.
> >
> >The patch ad4885d279b6: "IB/mlx4: Build the port IBoE GID table
> >properly under bonding" from Feb 5, 2014, leads to the following
> >Smatch complaint:
> >
> >drivers/infiniband/hw/mlx4/main.c:1749 mlx4_ib_scan_netdevs()
> > error: we previously assumed 'curr_netdev' could be null (see line 1722)
> >
> >drivers/infiniband/hw/mlx4/main.c
> > 1721
> > 1722 if (curr_netdev) {
> > ^^^^^^^^^^^
> >Check.
> >
> > 1723 port_state = (netif_running(curr_netdev) && netif_carrier_ok(curr_netdev)) ?
> > 1724 IB_PORT_ACTIVE : IB_PORT_DOWN;
> > 1725 mlx4_ib_set_default_gid(ibdev, curr_netdev, port);
> > 1726 } else {
> > 1727 reset_gid_table(ibdev, port);
> > 1728 }
> > 1729 /* if using bonding/team and a slave port is down, we don't the bond IP
> > 1730 * based gids in the table since flows that select port by gid may get
> > 1731 * the down port.
> > 1732 */
> > 1733 if (curr_master && (port_state == IB_PORT_DOWN)) {
> > 1734 reset_gid_table(ibdev, port);
> > 1735 mlx4_ib_set_default_gid(ibdev, curr_netdev, port);
> > 1736 }
> > 1737 /* if bonding is used it is possible that we add it to masters
> > 1738 * only after IP address is assigned to the net bonding
> > 1739 * interface.
> > 1740 */
> > 1741 if (curr_master && (old_master != curr_master)) {
> > 1742 reset_gid_table(ibdev, port);
> > 1743 mlx4_ib_set_default_gid(ibdev, curr_netdev, port);
> > 1744 mlx4_ib_get_dev_addr(curr_master, ibdev, port);
> > 1745 }
> > 1746
> > 1747 if (!curr_master && (old_master != curr_master)) {
> > 1748 reset_gid_table(ibdev, port);
> > 1749 mlx4_ib_set_default_gid(ibdev, curr_netdev, port);
> > ^^^^^^^^^^^
> >Dereferenced without checking.
> >
> > 1750 mlx4_ib_get_dev_addr(curr_netdev, ibdev, port);
> > 1751 }
> >
> >regards,
> >dan carpenter
> Not really a bug. (curr_master != NULL) implies (curr_netdev != NULL)

Ha ha. Take another look. That's what I was just explaining about! :)
On line 1743 when curr_master is non-NULL then Smatch doesn't complain
because it understands about the relationship between curr_master and
curr_netdev.

But here it is complaining about line 1749 where curr_master is NULL so
the implication doesn't apply.

Nice, huh?

regards,
dan carpenter