2 * Copyright (c) 2008, 2009, 2010 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
29 VLOG_DEFINE_THIS_MODULE(pktbuf)
31 /* Buffers are identified by a 32-bit opaque ID. We divide the ID
32 * into a buffer number (low bits) and a cookie (high bits). The buffer number
33 * is an index into an array of buffers. The cookie distinguishes between
34 * different packets that have occupied a single buffer. Thus, the more
35 * buffers we have, the lower-quality the cookie... */
37 #define PKTBUF_MASK (PKTBUF_CNT - 1)
38 #define PKTBUF_CNT (1u << PKTBUF_BITS)
40 #define COOKIE_BITS (32 - PKTBUF_BITS)
41 #define COOKIE_MAX ((1u << COOKIE_BITS) - 1)
43 #define OVERWRITE_MSECS 5000
46 struct ofpbuf *buffer;
48 long long int timeout;
53 struct packet packets[PKTBUF_CNT];
54 unsigned int buffer_idx;
55 unsigned int null_idx;
67 return xzalloc(sizeof *pktbuf_create());
71 pktbuf_destroy(struct pktbuf *pb)
76 for (i = 0; i < PKTBUF_CNT; i++) {
77 ofpbuf_delete(pb->packets[i].buffer);
84 make_id(unsigned int buffer_idx, unsigned int cookie)
86 return buffer_idx | (cookie << PKTBUF_BITS);
89 /* Attempts to allocate an OpenFlow packet buffer id within 'pb'. The packet
90 * buffer will store a copy of 'buffer' and the port number 'in_port', which
91 * should be the datapath port number on which 'buffer' was received.
93 * If successful, returns the packet buffer id (a number other than
94 * UINT32_MAX). pktbuf_retrieve() can later be used to retrieve the buffer and
95 * its input port number (buffers do expire after a time, so this is not
96 * guaranteed to be true forever). On failure, returns UINT32_MAX.
98 * The caller retains ownership of 'buffer'. */
100 pktbuf_save(struct pktbuf *pb, struct ofpbuf *buffer, uint16_t in_port)
102 struct packet *p = &pb->packets[pb->buffer_idx];
103 pb->buffer_idx = (pb->buffer_idx + 1) & PKTBUF_MASK;
105 if (time_msec() < p->timeout) {
108 ofpbuf_delete(p->buffer);
111 /* Don't use maximum cookie value since all-1-bits ID is special. */
112 if (++p->cookie >= COOKIE_MAX) {
115 p->buffer = ofpbuf_clone(buffer);
116 p->timeout = time_msec() + OVERWRITE_MSECS;
117 p->in_port = in_port;
118 return make_id(p - pb->packets, p->cookie);
122 * Allocates and returns a "null" packet buffer id. The returned packet buffer
123 * id is considered valid by pktbuf_retrieve(), but it is not associated with
124 * actual buffered data.
126 * This function is always successful.
128 * This is useful in one special case: with the current OpenFlow design, the
129 * "fail-open" code cannot always know whether a connection to a controller is
130 * actually valid until it receives a OFPT_PACKET_OUT or OFPT_FLOW_MOD request,
131 * but at that point the packet in question has already been forwarded (since
132 * we are still in "fail-open" mode). If the packet was buffered in the usual
133 * way, then the OFPT_PACKET_OUT or OFPT_FLOW_MOD would cause a duplicate
134 * packet in the network. Null packet buffer ids identify such a packet that
135 * has already been forwarded, so that Open vSwitch can quietly ignore the
136 * request to re-send it. (After that happens, the switch exits fail-open
139 * See the top-level comment in fail-open.c for an overview.
142 pktbuf_get_null(void)
144 return make_id(0, COOKIE_MAX);
147 /* Attempts to retrieve a saved packet with the given 'id' from 'pb'. Returns
148 * 0 if successful, otherwise an OpenFlow error code constructed with
151 * On success, ordinarily stores the buffered packet in '*bufferp' and the
152 * datapath port number on which the packet was received in '*in_port'. The
153 * caller becomes responsible for freeing the buffer. However, if 'id'
154 * identifies a "null" packet buffer (created with pktbuf_get_null()), stores
155 * NULL in '*bufferp' and UINT16_max in '*in_port'.
157 * On failure, stores NULL in in '*bufferp' and UINT16_MAX in '*in_port'. */
159 pktbuf_retrieve(struct pktbuf *pb, uint32_t id, struct ofpbuf **bufferp,
162 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 20);
167 VLOG_WARN_RL(&rl, "attempt to send buffered packet via connection "
169 return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_UNKNOWN);
172 p = &pb->packets[id & PKTBUF_MASK];
173 if (p->cookie == id >> PKTBUF_BITS) {
174 struct ofpbuf *buffer = p->buffer;
177 *in_port = p->in_port;
179 COVERAGE_INC(pktbuf_retrieved);
182 COVERAGE_INC(pktbuf_reuse_error);
183 VLOG_WARN_RL(&rl, "attempt to reuse buffer %08"PRIx32, id);
184 error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_EMPTY);
186 } else if (id >> PKTBUF_BITS != COOKIE_MAX) {
187 COVERAGE_INC(pktbuf_buffer_unknown);
188 VLOG_WARN_RL(&rl, "cookie mismatch: %08"PRIx32" != %08"PRIx32,
189 id, (id & PKTBUF_MASK) | (p->cookie << PKTBUF_BITS));
190 error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_UNKNOWN);
192 COVERAGE_INC(pktbuf_null_cookie);
193 VLOG_INFO_RL(&rl, "Received null cookie %08"PRIx32" (this is normal "
194 "if the switch was recently in fail-open mode)", id);
198 *in_port = UINT16_MAX;
203 pktbuf_discard(struct pktbuf *pb, uint32_t id)
205 struct packet *p = &pb->packets[id & PKTBUF_MASK];
206 if (p->cookie == id >> PKTBUF_BITS) {
207 ofpbuf_delete(p->buffer);