Hi Kuniyuki,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Kuniyuki-Iwashima/gtp-Use-for_each_netdev_rcu-in-gtp_genl_dump_pdp/20250108-143107
base:   net/main
patch link:    https://lore.kernel.org/r/20250108062834.11117-2-kuniyu%40amazon.com
patch subject: [PATCH v1 net 1/3] gtp: Use for_each_netdev_rcu() in gtp_genl_dump_pdp().
config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20250110/202501101052.pULMpd2R-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250110/202501101052.pULMpd2R-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot [off-list ref]
| Closes: https://lore.kernel.org/oe-kbuild-all/202501101052.pULMpd2R-lkp@intel.com/ (local)

All warnings (new ones prefixed by >>):

   drivers/net/gtp.c:2276:18: warning: variable 'gn' set but not used [-Wunused-but-set-variable]
    2276 |         struct gtp_net *gn;
         |                         ^

quoted

drivers/net/gtp.c:2288:31: warning: variable 'gtp' is uninitialized when used here [-Wuninitialized]

    2288 |                 if (last_gtp && last_gtp != gtp)
         |                                             ^~~
   drivers/net/gtp.c:2271:64: note: initialize the variable 'gtp' to silence this warning
    2271 |         struct gtp_dev *last_gtp = (struct gtp_dev *)cb->args[2], *gtp;
         |                                                                       ^
         |                                                                        = NULL
   2 warnings generated.


vim +/gtp +2288 drivers/net/gtp.c

459aa660eb1d8c Pablo Neira        2016-05-09  2267  
459aa660eb1d8c Pablo Neira        2016-05-09  2268  static int gtp_genl_dump_pdp(struct sk_buff *skb,
459aa660eb1d8c Pablo Neira        2016-05-09  2269  				struct netlink_callback *cb)
459aa660eb1d8c Pablo Neira        2016-05-09  2270  {
459aa660eb1d8c Pablo Neira        2016-05-09  2271  	struct gtp_dev *last_gtp = (struct gtp_dev *)cb->args[2], *gtp;
94a6d9fb88df43 Taehee Yoo         2019-12-11  2272  	int i, j, bucket = cb->args[0], skip = cb->args[1];
459aa660eb1d8c Pablo Neira        2016-05-09  2273  	struct net *net = sock_net(skb->sk);
766a8e9a311068 Kuniyuki Iwashima  2025-01-08  2274  	struct net_device *dev;
459aa660eb1d8c Pablo Neira        2016-05-09  2275  	struct pdp_ctx *pctx;
94a6d9fb88df43 Taehee Yoo         2019-12-11  2276  	struct gtp_net *gn;
94a6d9fb88df43 Taehee Yoo         2019-12-11  2277  
94a6d9fb88df43 Taehee Yoo         2019-12-11  2278  	gn = net_generic(net, gtp_net_id);
459aa660eb1d8c Pablo Neira        2016-05-09  2279  
459aa660eb1d8c Pablo Neira        2016-05-09  2280  	if (cb->args[4])
459aa660eb1d8c Pablo Neira        2016-05-09  2281  		return 0;
459aa660eb1d8c Pablo Neira        2016-05-09  2282  
94a6d9fb88df43 Taehee Yoo         2019-12-11  2283  	rcu_read_lock();
766a8e9a311068 Kuniyuki Iwashima  2025-01-08  2284  	for_each_netdev_rcu(net, dev) {
766a8e9a311068 Kuniyuki Iwashima  2025-01-08  2285  		if (dev->rtnl_link_ops != &gtp_link_ops)
766a8e9a311068 Kuniyuki Iwashima  2025-01-08  2286  			continue;
766a8e9a311068 Kuniyuki Iwashima  2025-01-08  2287  
459aa660eb1d8c Pablo Neira        2016-05-09 @2288  		if (last_gtp && last_gtp != gtp)
459aa660eb1d8c Pablo Neira        2016-05-09  2289  			continue;
459aa660eb1d8c Pablo Neira        2016-05-09  2290  		else
459aa660eb1d8c Pablo Neira        2016-05-09  2291  			last_gtp = NULL;
459aa660eb1d8c Pablo Neira        2016-05-09  2292  
94a6d9fb88df43 Taehee Yoo         2019-12-11  2293  		for (i = bucket; i < gtp->hash_size; i++) {
94a6d9fb88df43 Taehee Yoo         2019-12-11  2294  			j = 0;
94a6d9fb88df43 Taehee Yoo         2019-12-11  2295  			hlist_for_each_entry_rcu(pctx, &gtp->tid_hash[i],
94a6d9fb88df43 Taehee Yoo         2019-12-11  2296  						 hlist_tid) {
94a6d9fb88df43 Taehee Yoo         2019-12-11  2297  				if (j >= skip &&
94a6d9fb88df43 Taehee Yoo         2019-12-11  2298  				    gtp_genl_fill_info(skb,
459aa660eb1d8c Pablo Neira        2016-05-09  2299  					    NETLINK_CB(cb->skb).portid,
459aa660eb1d8c Pablo Neira        2016-05-09  2300  					    cb->nlh->nlmsg_seq,
846c68f7f1ac82 Yoshiyuki Kurauchi 2020-04-30  2301  					    NLM_F_MULTI,
94a6d9fb88df43 Taehee Yoo         2019-12-11  2302  					    cb->nlh->nlmsg_type, pctx)) {
459aa660eb1d8c Pablo Neira        2016-05-09  2303  					cb->args[0] = i;
94a6d9fb88df43 Taehee Yoo         2019-12-11  2304  					cb->args[1] = j;
459aa660eb1d8c Pablo Neira        2016-05-09  2305  					cb->args[2] = (unsigned long)gtp;
459aa660eb1d8c Pablo Neira        2016-05-09  2306  					goto out;
459aa660eb1d8c Pablo Neira        2016-05-09  2307  				}
94a6d9fb88df43 Taehee Yoo         2019-12-11  2308  				j++;
459aa660eb1d8c Pablo Neira        2016-05-09  2309  			}
94a6d9fb88df43 Taehee Yoo         2019-12-11  2310  			skip = 0;
459aa660eb1d8c Pablo Neira        2016-05-09  2311  		}
94a6d9fb88df43 Taehee Yoo         2019-12-11  2312  		bucket = 0;
459aa660eb1d8c Pablo Neira        2016-05-09  2313  	}
459aa660eb1d8c Pablo Neira        2016-05-09  2314  	cb->args[4] = 1;
459aa660eb1d8c Pablo Neira        2016-05-09  2315  out:
94a6d9fb88df43 Taehee Yoo         2019-12-11  2316  	rcu_read_unlock();
459aa660eb1d8c Pablo Neira        2016-05-09  2317  	return skb->len;
459aa660eb1d8c Pablo Neira        2016-05-09  2318  }
459aa660eb1d8c Pablo Neira        2016-05-09  2319  

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