Hi Paolo, Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on net-next/master] url: https://github.com/0day-ci/linux/commits/Paolo-Abeni/TC-refactor-act_mirred-packets-re-injection/20180729-102154 config: xtensa-allyesconfig (attached as .config) compiler: xtensa-linux-gcc (GCC) 8.1.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree GCC_VERSION=8.1.0 make.cross ARCH=xtensa Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings All warnings (new ones prefixed by >>): net/sched/act_mirred.c: In function 'tcf_mirred': >> net/sched/act_mirred.c:268:6: warning: 'is_redirect' may be used >> uninitialized in this function [-Wmaybe-uninitialized] if (is_redirect) ^ vim +/is_redirect +268 net/sched/act_mirred.c 182 183 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a, 184 struct tcf_result *res) 185 { 186 struct tcf_mirred *m = to_mirred(a); 187 struct sk_buff *skb2 = skb; 188 bool m_mac_header_xmit; 189 struct net_device *dev; 190 int retval, err = 0; 191 bool use_reinsert; 192 bool want_ingress; 193 bool is_redirect; 194 int m_eaction; 195 int mac_len; 196 197 tcf_lastuse_update(&m->tcf_tm); 198 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 199 200 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 201 m_eaction = READ_ONCE(m->tcfm_eaction); 202 retval = READ_ONCE(m->tcf_action); 203 dev = rcu_dereference_bh(m->tcfm_dev); 204 if (unlikely(!dev)) { 205 pr_notice_once("tc mirred: target device is gone\n"); 206 goto out; 207 } 208 209 if (unlikely(!(dev->flags & IFF_UP))) { 210 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 211 dev->name); 212 goto out; 213 } 214 215 /* we could easily avoid the clone only if called by ingress and clsact; 216 * since we can't easily detect the clsact caller, skip clone only for 217 * ingress - that covers the TC S/W datapath. 218 */ 219 is_redirect = tcf_mirred_is_act_redirect(m_eaction); 220 use_reinsert = skb_at_tc_ingress(skb) && is_redirect && 221 tcf_mirred_can_reinsert(retval); 222 if (!use_reinsert) { 223 skb2 = skb_clone(skb, GFP_ATOMIC); 224 if (!skb2) 225 goto out; 226 } 227 228 /* If action's target direction differs than filter's direction, 229 * and devices expect a mac header on xmit, then mac push/pull is 230 * needed. 231 */ 232 want_ingress = tcf_mirred_act_wants_ingress(m_eaction); 233 if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) { 234 if (!skb_at_tc_ingress(skb)) { 235 /* caught at egress, act ingress: pull mac */ 236 mac_len = skb_network_header(skb) - skb_mac_header(skb); 237 skb_pull_rcsum(skb2, mac_len); 238 } else { 239 /* caught at ingress, act egress: push mac */ 240 skb_push_rcsum(skb2, skb->mac_len); 241 } 242 } 243 244 skb2->skb_iif = skb->dev->ifindex; 245 skb2->dev = dev; 246 247 /* mirror is always swallowed */ 248 if (is_redirect) { 249 skb2->tc_redirected = 1; 250 skb2->tc_from_ingress = skb2->tc_at_ingress; 251 252 /* let's the caller reinsert the packet, if possible */ 253 if (use_reinsert) { 254 res->ingress = want_ingress; 255 res->qstats = this_cpu_ptr(m->common.cpu_qstats); 256 return TC_ACT_REINSERT; 257 } 258 } 259 260 if (!want_ingress) 261 err = dev_queue_xmit(skb2); 262 else 263 err = netif_receive_skb(skb2); 264 265 if (err) { 266 out: 267 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); > 268 if (is_redirect) 269 retval = TC_ACT_SHOT; 270 } 271 272 return retval; 273 } 274 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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