Re: [PATCH net] net: dsa: Centralize validation of VLAN configuration

[kernel test robot <lkp@intel.com>]

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Hi Tobias,

I love your patch! Perhaps something to improve:

[auto build test WARNING on net/master]

url:    https://github.com/0day-ci/linux/commits/Tobias-Waldekranz/net-dsa-Centralize-validation-of-VLAN-configuration/20210316-035618
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git a25f822285420486f5da434efc8d940d42a83bce
config: powerpc-randconfig-r006-20210316 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 50c7504a93fdb90c26870db8c8ea7add895c7725)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # https://github.com/0day-ci/linux/commit/9a35f7597b676a3bdaa9dd753e0a7d11fb132ed5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Tobias-Waldekranz/net-dsa-Centralize-validation-of-VLAN-configuration/20210316-035618
        git checkout 9a35f7597b676a3bdaa9dd753e0a7d11fb132ed5
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/dsa/slave.c:2074:12: warning: variable 'err' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
                   else if (is_vlan_dev(info->upper_dev))
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/dsa/slave.c:2077:7: note: uninitialized use occurs here
                   if (err)
                       ^~~
   net/dsa/slave.c:2074:8: note: remove the 'if' if its condition is always true
                   else if (is_vlan_dev(info->upper_dev))
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/dsa/slave.c:2070:10: note: initialize the variable 'err' to silence this warning
                   int err;
                          ^
                           = 0
   1 warning generated.


vim +2074 net/dsa/slave.c

  2059	
  2060	static int dsa_slave_netdevice_event(struct notifier_block *nb,
  2061					     unsigned long event, void *ptr)
  2062	{
  2063		struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  2064	
  2065		switch (event) {
  2066		case NETDEV_PRECHANGEUPPER: {
  2067			struct netdev_notifier_changeupper_info *info = ptr;
  2068			struct dsa_switch *ds;
  2069			struct dsa_port *dp;
  2070			int err;
  2071	
  2072			if (is_vlan_dev(dev))
  2073				err = dsa_prevent_bridging_8021q_upper(dev, ptr);
> 2074			else if (is_vlan_dev(info->upper_dev))
  2075				err = dsa_slave_check_8021q_upper(dev, ptr);
  2076	
  2077			if (err)
  2078				return err;
  2079	
  2080			if (!dsa_slave_dev_check(dev))
  2081				return NOTIFY_DONE;
  2082	
  2083			dp = dsa_slave_to_port(dev);
  2084			ds = dp->ds;
  2085	
  2086			if (ds->ops->port_prechangeupper) {
  2087				err = ds->ops->port_prechangeupper(ds, dp->index, info);
  2088				if (err)
  2089					return notifier_from_errno(err);
  2090			}
  2091			break;
  2092		}
  2093		case NETDEV_CHANGEUPPER:
  2094			if (dsa_slave_dev_check(dev))
  2095				return dsa_slave_changeupper(dev, ptr);
  2096	
  2097			if (netif_is_lag_master(dev))
  2098				return dsa_slave_lag_changeupper(dev, ptr);
  2099	
  2100			break;
  2101		case NETDEV_CHANGELOWERSTATE: {
  2102			struct netdev_notifier_changelowerstate_info *info = ptr;
  2103			struct dsa_port *dp;
  2104			int err;
  2105	
  2106			if (!dsa_slave_dev_check(dev))
  2107				break;
  2108	
  2109			dp = dsa_slave_to_port(dev);
  2110	
  2111			err = dsa_port_lag_change(dp, info->lower_state_info);
  2112			return notifier_from_errno(err);
  2113		}
  2114		case NETDEV_GOING_DOWN: {
  2115			struct dsa_port *dp, *cpu_dp;
  2116			struct dsa_switch_tree *dst;
  2117			LIST_HEAD(close_list);
  2118	
  2119			if (!netdev_uses_dsa(dev))
  2120				return NOTIFY_DONE;
  2121	
  2122			cpu_dp = dev->dsa_ptr;
  2123			dst = cpu_dp->ds->dst;
  2124	
  2125			list_for_each_entry(dp, &dst->ports, list) {
  2126				if (!dsa_is_user_port(dp->ds, dp->index))
  2127					continue;
  2128	
  2129				list_add(&dp->slave->close_list, &close_list);
  2130			}
  2131	
  2132			dev_close_many(&close_list, true);
  2133	
  2134			return NOTIFY_OK;
  2135		}
  2136		default:
  2137			break;
  2138		}
  2139	
  2140		return NOTIFY_DONE;
  2141	}
  2142	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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