FreeBSD/Linux Kernel Cross Reference
sys/net/netisr.c
1 /*-
2 * Copyright (c) 2001,2002,2003 Jonathan Lemon <jlemon@FreeBSD.org>
3 * Copyright (c) 1997, Stefan Esser <se@freebsd.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD$
28 */
29
30 #include "opt_device_polling.h"
31
32 #include <sys/param.h>
33 #include <sys/bus.h>
34 #include <sys/rtprio.h>
35 #include <sys/systm.h>
36 #include <sys/interrupt.h>
37 #include <sys/kernel.h>
38 #include <sys/kthread.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/proc.h>
42 #include <sys/random.h>
43 #include <sys/resourcevar.h>
44 #include <sys/sysctl.h>
45 #include <sys/unistd.h>
46 #include <machine/atomic.h>
47 #include <machine/cpu.h>
48 #include <machine/stdarg.h>
49
50 #include <sys/mbuf.h>
51 #include <sys/socket.h>
52
53 #include <net/if.h>
54 #include <net/if_types.h>
55 #include <net/if_var.h>
56 #include <net/netisr.h>
57
58 volatile unsigned int netisr; /* scheduling bits for network */
59
60 struct netisr {
61 netisr_t *ni_handler;
62 struct ifqueue *ni_queue;
63 int ni_flags;
64 } netisrs[32];
65
66 static void *net_ih;
67
68 void
69 legacy_setsoftnet(void)
70 {
71 swi_sched(net_ih, 0);
72 }
73
74 void
75 netisr_register(int num, netisr_t *handler, struct ifqueue *inq, int flags)
76 {
77
78 KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
79 ("bad isr %d", num));
80 netisrs[num].ni_handler = handler;
81 netisrs[num].ni_queue = inq;
82 netisrs[num].ni_flags = flags;
83 }
84
85 void
86 netisr_unregister(int num)
87 {
88 struct netisr *ni;
89
90 KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
91 ("bad isr %d", num));
92 ni = &netisrs[num];
93 ni->ni_handler = NULL;
94 if (ni->ni_queue != NULL)
95 IF_DRAIN(ni->ni_queue);
96 ni->ni_queue = NULL;
97 }
98
99 struct isrstat {
100 int isrs_count; /* dispatch count */
101 int isrs_directed; /* ...directly dispatched */
102 int isrs_deferred; /* ...queued instead */
103 int isrs_queued; /* intentionally queueued */
104 int isrs_drop; /* dropped 'cuz no handler */
105 int isrs_swi_count; /* swi_net handlers called */
106 };
107 static struct isrstat isrstat;
108
109 SYSCTL_NODE(_net, OID_AUTO, isr, CTLFLAG_RW, 0, "netisr counters");
110
111 static int netisr_direct = 1;
112 SYSCTL_INT(_net_isr, OID_AUTO, direct, CTLFLAG_RW,
113 &netisr_direct, 0, "enable direct dispatch");
114 TUNABLE_INT("net.isr.direct", &netisr_direct);
115
116 SYSCTL_INT(_net_isr, OID_AUTO, count, CTLFLAG_RD,
117 &isrstat.isrs_count, 0, "");
118 SYSCTL_INT(_net_isr, OID_AUTO, directed, CTLFLAG_RD,
119 &isrstat.isrs_directed, 0, "");
120 SYSCTL_INT(_net_isr, OID_AUTO, deferred, CTLFLAG_RD,
121 &isrstat.isrs_deferred, 0, "");
122 SYSCTL_INT(_net_isr, OID_AUTO, queued, CTLFLAG_RD,
123 &isrstat.isrs_queued, 0, "");
124 SYSCTL_INT(_net_isr, OID_AUTO, drop, CTLFLAG_RD,
125 &isrstat.isrs_drop, 0, "");
126 SYSCTL_INT(_net_isr, OID_AUTO, swi_count, CTLFLAG_RD,
127 &isrstat.isrs_swi_count, 0, "");
128
129 /*
130 * Process all packets currently present in a netisr queue. Used to
131 * drain an existing set of packets waiting for processing when we
132 * begin direct dispatch, to avoid processing packets out of order.
133 */
134 static void
135 netisr_processqueue(struct netisr *ni)
136 {
137 struct mbuf *m;
138
139 for (;;) {
140 IF_DEQUEUE(ni->ni_queue, m);
141 if (m == NULL)
142 break;
143 ni->ni_handler(m);
144 }
145 }
146
147 /*
148 * Call the netisr directly instead of queueing the packet, if possible.
149 */
150 void
151 netisr_dispatch(int num, struct mbuf *m)
152 {
153 struct netisr *ni;
154
155 isrstat.isrs_count++; /* XXX redundant */
156 KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
157 ("bad isr %d", num));
158 ni = &netisrs[num];
159 if (ni->ni_queue == NULL) {
160 isrstat.isrs_drop++;
161 m_freem(m);
162 return;
163 }
164 /*
165 * Do direct dispatch only for MPSAFE netisrs (and
166 * only when enabled). Note that when a netisr is
167 * marked MPSAFE we permit multiple concurrent instances
168 * to run. We guarantee only the order in which
169 * packets are processed for each "dispatch point" in
170 * the system (i.e. call to netisr_dispatch or
171 * netisr_queue). This insures ordering of packets
172 * from an interface but does not guarantee ordering
173 * between multiple places in the system (e.g. IP
174 * dispatched from interfaces vs. IP queued from IPSec).
175 */
176 if (netisr_direct && (ni->ni_flags & NETISR_MPSAFE)) {
177 isrstat.isrs_directed++;
178 /*
179 * NB: We used to drain the queue before handling
180 * the packet but now do not. Doing so here will
181 * not preserve ordering so instead we fallback to
182 * guaranteeing order only from dispatch points
183 * in the system (see above).
184 */
185 ni->ni_handler(m);
186 } else {
187 isrstat.isrs_deferred++;
188 if (IF_HANDOFF(ni->ni_queue, m, NULL))
189 schednetisr(num);
190 }
191 }
192
193 /*
194 * Same as above, but always queue.
195 * This is either used in places where we are not confident that
196 * direct dispatch is possible, or where queueing is required.
197 * It returns (0) on success and ERRNO on failure. On failure the
198 * mbuf has been free'd.
199 */
200 int
201 netisr_queue(int num, struct mbuf *m)
202 {
203 struct netisr *ni;
204
205 KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
206 ("bad isr %d", num));
207 ni = &netisrs[num];
208 if (ni->ni_queue == NULL) {
209 isrstat.isrs_drop++;
210 m_freem(m);
211 return (ENXIO);
212 }
213 isrstat.isrs_queued++;
214 if (!IF_HANDOFF(ni->ni_queue, m, NULL))
215 return (ENOBUFS); /* IF_HANDOFF has free'd the mbuf */
216 schednetisr(num);
217 return (0);
218 }
219
220 static void
221 swi_net(void *dummy)
222 {
223 struct netisr *ni;
224 u_int bits;
225 int i;
226 #ifdef DEVICE_POLLING
227 const int polling = 1;
228 #else
229 const int polling = 0;
230 #endif
231
232 do {
233 bits = atomic_readandclear_int(&netisr);
234 if (bits == 0)
235 break;
236 while ((i = ffs(bits)) != 0) {
237 isrstat.isrs_swi_count++;
238 i--;
239 bits &= ~(1 << i);
240 ni = &netisrs[i];
241 if (ni->ni_handler == NULL) {
242 printf("swi_net: unregistered isr %d.\n", i);
243 continue;
244 }
245 if ((ni->ni_flags & NETISR_MPSAFE) == 0) {
246 mtx_lock(&Giant);
247 if (ni->ni_queue == NULL)
248 ni->ni_handler(NULL);
249 else
250 netisr_processqueue(ni);
251 mtx_unlock(&Giant);
252 } else {
253 if (ni->ni_queue == NULL)
254 ni->ni_handler(NULL);
255 else
256 netisr_processqueue(ni);
257 }
258 }
259 } while (polling);
260 }
261
262 static void
263 start_netisr(void *dummy)
264 {
265
266 if (swi_add(NULL, "net", swi_net, NULL, SWI_NET, INTR_MPSAFE, &net_ih))
267 panic("start_netisr");
268 }
269 SYSINIT(start_netisr, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_netisr, NULL)
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