From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Wed, 10 Jun 2015 15:53:42 +0000 Subject: re: mpls: Add MPLS entropy label in flow_keys Message-Id: <20150610155342.GM10549@mwanda> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kernel-janitors@vger.kernel.org Hello Tom Herbert, The patch b3baa0fbd02a: "mpls: Add MPLS entropy label in flow_keys" from Jun 4, 2015, leads to the following static checker warning: net/core/flow_dissector.c:303 __skb_flow_dissect() warn: masked condition '(() & 4294963200) = 7' is always false. net/core/flow_dissector.c 299 if (!hdr) 300 return false; 301 302 if ((ntohl(hdr[0].entry) & MPLS_LS_LABEL_MASK) = 303 MPLS_LABEL_ENTROPY) { #define MPLS_LS_LABEL_MASK 0xFFFFF000 #define MPLS_LABEL_ENTROPY 7 /* RFC6790 */ This can never be true. Not sure what was intended. 304 if (skb_flow_dissector_uses_key(flow_dissector, 305 FLOW_DISSECTOR_KEY_MPLS_ENTROPY)) { 306 key_keyid = skb_flow_dissector_target(flow_dissector, 307 FLOW_DISSECTOR_KEY_MPLS_ENTROPY, 308 target_container); 309 key_keyid->keyid = hdr[1].entry & 310 htonl(MPLS_LS_LABEL_MASK); 311 } 312 313 key_basic->n_proto = proto; 314 key_basic->ip_proto = ip_proto; 315 key_control->thoff = (u16)nhoff; 316 317 return true; 318 } 319 320 return true; 321 } regards, dan carpenter