BCC: lkp(a)intel.com
CC: kbuild-all(a)lists.01.org
In-Reply-To: <20220930223042.351022-1-vinicius.gomes@intel.com>
References: <20220930223042.351022-1-vinicius.gomes@intel.com>
TO: Vinicius Costa Gomes <vinicius.gomes@intel.com>
TO: netdev(a)vger.kernel.org
CC: Vinicius Costa Gomes <vinicius.gomes@intel.com>
CC: vladimir.oltean(a)nxp.com
CC: yannick.vignon(a)nxp.com
CC: jhs(a)mojatatu.com
CC: xiyou.wangcong(a)gmail.com
CC: kuba(a)kernel.org
CC: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>

Hi Vinicius,

I love your patch! Perhaps something to improve:

[auto build test WARNING on net/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Vinicius-Costa-Gomes/net-sched-taprio-Fix-crash-when-adding-child-qdisc/20221001-063146
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git 0bafedc536499a533dd7a94c9c980d53f3ca2afc
:::::: branch date: 17 hours ago
:::::: commit date: 17 hours ago
config: s390-randconfig-m031-20220925
compiler: s390-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
net/sched/sch_taprio.c:1802 taprio_graft() warn: variable dereferenced before check 'new' (see line 1800)

vim +/new +1802 net/sched/sch_taprio.c

5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1779  
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1780  static int taprio_graft(struct Qdisc *sch, unsigned long cl,
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1781  			struct Qdisc *new, struct Qdisc **old,
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1782  			struct netlink_ext_ack *extack)
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1783  {
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1784  	struct taprio_sched *q = qdisc_priv(sch);
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1785  	struct net_device *dev = qdisc_dev(sch);
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1786  	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1787  
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1788  	if (!dev_queue)
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1789  		return -EINVAL;
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1790  
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1791  	if (dev->flags & IFF_UP)
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1792  		dev_deactivate(dev);
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1793  
13511704f8d759 Yannick Vignon       2021-05-11  1794  	if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
13511704f8d759 Yannick Vignon       2021-05-11  1795  		*old = dev_graft_qdisc(dev_queue, new);
13511704f8d759 Yannick Vignon       2021-05-11  1796  	} else {
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1797  		*old = q->qdiscs[cl - 1];
13511704f8d759 Yannick Vignon       2021-05-11  1798  	}
9446a10d946e00 Vinicius Costa Gomes 2022-09-30  1799  	q->qdiscs[cl - 1] = new;
9446a10d946e00 Vinicius Costa Gomes 2022-09-30 @1800  	qdisc_refcount_inc(new);
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1801  
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28 @1802  	if (new)
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1803  		new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1804  
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1805  	if (dev->flags & IFF_UP)
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1806  		dev_activate(dev);
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1807  
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1808  	return 0;
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1809  }
5a781ccbd19e46 Vinicius Costa Gomes 2018-09-28  1810  

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