xref: /freebsd/sys/netinet/sctp_os_bsd.h (revision 9162f64b58d01ec01481d60b6cdc06ffd8e8c7fc)
1 /*-
2  * Copyright (c) 2006-2007, by Cisco Systems, Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *
7  * a) Redistributions of source code must retain the above copyright notice,
8  *   this list of conditions and the following disclaimer.
9  *
10  * b) Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *   the documentation and/or other materials provided with the distribution.
13  *
14  * c) Neither the name of Cisco Systems, Inc. nor the names of its
15  *    contributors may be used to endorse or promote products derived
16  *    from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
20  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28  * THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 #ifndef __sctp_os_bsd_h__
33 #define __sctp_os_bsd_h__
34 /*
35  * includes
36  */
37 #include "opt_ipsec.h"
38 #include "opt_compat.h"
39 #include "opt_inet6.h"
40 #include "opt_inet.h"
41 #include "opt_sctp.h"
42 
43 #include <sys/param.h>
44 #include <sys/ktr.h>
45 #include <sys/systm.h>
46 #include <sys/malloc.h>
47 #include <sys/kernel.h>
48 #include <sys/sysctl.h>
49 #include <sys/mbuf.h>
50 #include <sys/protosw.h>
51 #include <sys/socket.h>
52 #include <sys/socketvar.h>
53 #include <sys/jail.h>
54 #include <sys/sysctl.h>
55 #include <sys/resourcevar.h>
56 #include <sys/uio.h>
57 #include <sys/lock.h>
58 #include <sys/rwlock.h>
59 #include <sys/kthread.h>
60 #include <sys/priv.h>
61 #include <sys/random.h>
62 #include <sys/limits.h>
63 #include <sys/queue.h>
64 #include <sys/vimage.h>
65 #include <machine/cpu.h>
66 
67 #include <net/if.h>
68 #include <net/if_types.h>
69 #include <net/if_var.h>
70 #include <net/route.h>
71 #include <net/vnet.h>
72 
73 #include <netinet/in.h>
74 #include <netinet/in_systm.h>
75 #include <netinet/ip.h>
76 #include <netinet/in_pcb.h>
77 #include <netinet/in_var.h>
78 #include <netinet/ip_var.h>
79 #include <netinet/ip_icmp.h>
80 #include <netinet/icmp_var.h>
81 #include <netinet/vinet.h>
82 
83 #ifdef IPSEC
84 #include <netipsec/ipsec.h>
85 #include <netipsec/key.h>
86 #endif				/* IPSEC */
87 
88 #ifdef INET6
89 #include <sys/domain.h>
90 #ifdef IPSEC
91 #include <netipsec/ipsec6.h>
92 #endif
93 #include <netinet/ip6.h>
94 #include <netinet6/ip6_var.h>
95 #include <netinet6/in6_pcb.h>
96 #include <netinet/icmp6.h>
97 #include <netinet6/ip6protosw.h>
98 #include <netinet6/nd6.h>
99 #include <netinet6/scope6_var.h>
100 #include <netinet6/vinet6.h>
101 #endif				/* INET6 */
102 
103 
104 #include <netinet/ip_options.h>
105 
106 #ifndef in6pcb
107 #define in6pcb		inpcb
108 #endif
109 /* Declare all the malloc names for all the various mallocs */
110 MALLOC_DECLARE(SCTP_M_MAP);
111 MALLOC_DECLARE(SCTP_M_STRMI);
112 MALLOC_DECLARE(SCTP_M_STRMO);
113 MALLOC_DECLARE(SCTP_M_ASC_ADDR);
114 MALLOC_DECLARE(SCTP_M_ASC_IT);
115 MALLOC_DECLARE(SCTP_M_AUTH_CL);
116 MALLOC_DECLARE(SCTP_M_AUTH_KY);
117 MALLOC_DECLARE(SCTP_M_AUTH_HL);
118 MALLOC_DECLARE(SCTP_M_AUTH_IF);
119 MALLOC_DECLARE(SCTP_M_STRESET);
120 MALLOC_DECLARE(SCTP_M_CMSG);
121 MALLOC_DECLARE(SCTP_M_COPYAL);
122 MALLOC_DECLARE(SCTP_M_VRF);
123 MALLOC_DECLARE(SCTP_M_IFA);
124 MALLOC_DECLARE(SCTP_M_IFN);
125 MALLOC_DECLARE(SCTP_M_TIMW);
126 MALLOC_DECLARE(SCTP_M_MVRF);
127 MALLOC_DECLARE(SCTP_M_ITER);
128 MALLOC_DECLARE(SCTP_M_SOCKOPT);
129 
130 #if defined(SCTP_LOCAL_TRACE_BUF)
131 
132 #define SCTP_GET_CYCLECOUNT get_cyclecount()
133 #define SCTP_CTR6 sctp_log_trace
134 
135 #else
136 #define SCTP_CTR6 CTR6
137 #endif
138 
139 #define SCTP_BASE_INFO(__m) system_base_info.sctppcbinfo.__m
140 #define SCTP_BASE_STATS system_base_info.sctpstat
141 #define SCTP_BASE_STAT(__m)     system_base_info.sctpstat.__m
142 #define SCTP_BASE_SYSCTL(__m) system_base_info.sctpsysctl.__m
143 #define SCTP_BASE_VAR(__m) system_base_info.__m
144 
145 /*
146  * Macros to expand out globals defined by various modules
147  * to either a real global or a virtualized instance of one,
148  * depending on whether VIMAGE is defined.
149  */
150 /* first define modules that supply us information */
151 #define MOD_NET net
152 #define MOD_INET inet
153 #define MOD_INET6 inet6
154 #define MOD_IPSEC ipsec
155 
156 /* then define the macro(s) that hook into the vimage macros */
157 #if defined(__FreeBSD__) && __FreeBSD_version >= 800056
158 #define MODULE_GLOBAL(__MODULE, __SYMBOL) V_ ## __SYMBOL
159 #else
160 #define MODULE_GLOBAL(__MODULE, __SYMBOL) (__SYMBOL)
161 #endif
162 /*
163  *
164  */
165 #define USER_ADDR_NULL	(NULL)	/* FIX ME: temp */
166 #define SCTP_LIST_EMPTY(list)	LIST_EMPTY(list)
167 
168 #if defined(SCTP_DEBUG)
169 #define SCTPDBG(level, params...)					\
170 {									\
171     do {								\
172 	if (SCTP_BASE_SYSCTL(sctp_debug_on) & level ) {			\
173 	    printf(params);						\
174 	}								\
175     } while (0);							\
176 }
177 #define SCTPDBG_ADDR(level, addr)					\
178 {									\
179     do {								\
180 	if (SCTP_BASE_SYSCTL(sctp_debug_on) & level ) {			\
181 	    sctp_print_address(addr);					\
182 	}								\
183     } while (0);							\
184 }
185 #define SCTPDBG_PKT(level, iph, sh)					\
186 {									\
187     do {								\
188 	    if (SCTP_BASE_SYSCTL(sctp_debug_on) & level) {		\
189 		    sctp_print_address_pkt(iph, sh);			\
190 	    }								\
191     } while (0);							\
192 }
193 #else
194 #define SCTPDBG(level, params...)
195 #define SCTPDBG_ADDR(level, addr)
196 #define SCTPDBG_PKT(level, iph, sh)
197 #endif
198 #define SCTP_PRINTF(params...)	printf(params)
199 
200 #ifdef SCTP_LTRACE_CHUNKS
201 #define SCTP_LTRACE_CHK(a, b, c, d) if(SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_LTRACE_CHUNK_ENABLE) CTR6(KTR_SUBSYS, "SCTP:%d[%d]:%x-%x-%x-%x", SCTP_LOG_CHUNK_PROC, 0, a, b, c, d)
202 #else
203 #define SCTP_LTRACE_CHK(a, b, c, d)
204 #endif
205 
206 #ifdef SCTP_LTRACE_ERRORS
207 #define SCTP_LTRACE_ERR_RET_PKT(m, inp, stcb, net, file, err) if(SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_LTRACE_ERROR_ENABLE) \
208                                                          printf("mbuf:%p inp:%p stcb:%p net:%p file:%x line:%d error:%d\n", \
209 								     m, inp, stcb, net, file, __LINE__, err);
210 #define SCTP_LTRACE_ERR_RET(inp, stcb, net, file, err) if(SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_LTRACE_ERROR_ENABLE) \
211                                                           printf("inp:%p stcb:%p net:%p file:%x line:%d error:%d\n", \
212 								     inp, stcb, net, file, __LINE__, err);
213 #else
214 #define SCTP_LTRACE_ERR_RET_PKT(m, inp, stcb, net, file, err)
215 #define SCTP_LTRACE_ERR_RET(inp, stcb, net, file, err)
216 #endif
217 
218 
219 /*
220  * Local address and interface list handling
221  */
222 #define SCTP_MAX_VRF_ID		0
223 #define SCTP_SIZE_OF_VRF_HASH	3
224 #define SCTP_IFNAMSIZ		IFNAMSIZ
225 #define SCTP_DEFAULT_VRFID	0
226 #define SCTP_VRF_ADDR_HASH_SIZE	16
227 #define SCTP_VRF_IFN_HASH_SIZE	3
228 #define	SCTP_INIT_VRF_TABLEID(vrf)
229 
230 #define SCTP_IFN_IS_IFT_LOOP(ifn) ((ifn)->ifn_type == IFT_LOOP)
231 #define SCTP_ROUTE_IS_REAL_LOOP(ro) ((ro)->ro_rt && (ro)->ro_rt->rt_ifa && (ro)->ro_rt->rt_ifa->ifa_ifp && (ro)->ro_rt->rt_ifa->ifa_ifp->if_type == IFT_LOOP)
232 
233 /*
234  * Access to IFN's to help with src-addr-selection
235  */
236 /* This could return VOID if the index works but for BSD we provide both. */
237 #define SCTP_GET_IFN_VOID_FROM_ROUTE(ro) (void *)ro->ro_rt->rt_ifp
238 #define SCTP_GET_IF_INDEX_FROM_ROUTE(ro) (ro)->ro_rt->rt_ifp->if_index
239 #define SCTP_ROUTE_HAS_VALID_IFN(ro) ((ro)->ro_rt && (ro)->ro_rt->rt_ifp)
240 
241 /*
242  * general memory allocation
243  */
244 #define SCTP_MALLOC(var, type, size, name) \
245     do { \
246 	var = (type)malloc(size, name, M_NOWAIT); \
247     } while (0)
248 
249 #define SCTP_FREE(var, type)	free(var, type)
250 
251 #define SCTP_MALLOC_SONAME(var, type, size) \
252     do { \
253 	var = (type)malloc(size, M_SONAME, M_WAITOK | M_ZERO); \
254     } while (0)
255 
256 #define SCTP_FREE_SONAME(var)	free(var, M_SONAME)
257 
258 #define SCTP_PROCESS_STRUCT struct proc *
259 
260 /*
261  * zone allocation functions
262  */
263 #include <vm/uma.h>
264 
265 /* SCTP_ZONE_INIT: initialize the zone */
266 typedef struct uma_zone *sctp_zone_t;
267 
268 #define UMA_ZFLAG_FULL	0x0020
269 #define SCTP_ZONE_INIT(zone, name, size, number) { \
270 	zone = uma_zcreate(name, size, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,\
271 		UMA_ZFLAG_FULL); \
272 	uma_zone_set_max(zone, number); \
273 }
274 
275 #define SCTP_ZONE_DESTROY(zone) uma_zdestroy(zone)
276 
277 /* SCTP_ZONE_GET: allocate element from the zone */
278 #define SCTP_ZONE_GET(zone, type) \
279 	(type *)uma_zalloc(zone, M_NOWAIT);
280 
281 /* SCTP_ZONE_FREE: free element from the zone */
282 #define SCTP_ZONE_FREE(zone, element) \
283 	uma_zfree(zone, element);
284 
285 #define SCTP_HASH_INIT(size, hashmark) hashinit_flags(size, M_PCB, hashmark, HASH_NOWAIT)
286 #define SCTP_HASH_FREE(table, hashmark) hashdestroy(table, M_PCB, hashmark)
287 
288 #define SCTP_M_COPYM	m_copym
289 
290 /*
291  * timers
292  */
293 #include <sys/callout.h>
294 typedef struct callout sctp_os_timer_t;
295 
296 
297 #define SCTP_OS_TIMER_INIT(tmr)	callout_init(tmr, 1)
298 #define SCTP_OS_TIMER_START	callout_reset
299 #define SCTP_OS_TIMER_STOP	callout_stop
300 #define SCTP_OS_TIMER_STOP_DRAIN callout_drain
301 #define SCTP_OS_TIMER_PENDING	callout_pending
302 #define SCTP_OS_TIMER_ACTIVE	callout_active
303 #define SCTP_OS_TIMER_DEACTIVATE callout_deactivate
304 
305 #define sctp_get_tick_count() (ticks)
306 
307 #define SCTP_UNUSED __attribute__((unused))
308 
309 /*
310  * Functions
311  */
312 /* Mbuf manipulation and access macros  */
313 #define SCTP_BUF_LEN(m) (m->m_len)
314 #define SCTP_BUF_NEXT(m) (m->m_next)
315 #define SCTP_BUF_NEXT_PKT(m) (m->m_nextpkt)
316 #define SCTP_BUF_RESV_UF(m, size) m->m_data += size
317 #define SCTP_BUF_AT(m, size) m->m_data + size
318 #define SCTP_BUF_IS_EXTENDED(m) (m->m_flags & M_EXT)
319 #define SCTP_BUF_EXTEND_SIZE(m) (m->m_ext.ext_size)
320 #define SCTP_BUF_TYPE(m) (m->m_type)
321 #define SCTP_BUF_RECVIF(m) (m->m_pkthdr.rcvif)
322 #define SCTP_BUF_PREPEND	M_PREPEND
323 
324 #define SCTP_ALIGN_TO_END(m, len) if(m->m_flags & M_PKTHDR) { \
325                                      MH_ALIGN(m, len); \
326                                   } else if ((m->m_flags & M_EXT) == 0) { \
327                                      M_ALIGN(m, len); \
328                                   }
329 
330 /* We make it so if you have up to 4 threads
331  * writting based on the default size of
332  * the packet log 65 k, that would be
333  * 4 16k packets before we would hit
334  * a problem.
335  */
336 #define SCTP_PKTLOG_WRITERS_NEED_LOCK 3
337 
338 /*************************/
339 /*      MTU              */
340 /*************************/
341 #define SCTP_GATHER_MTU_FROM_IFN_INFO(ifn, ifn_index, af) ((struct ifnet *)ifn)->if_mtu
342 #define SCTP_GATHER_MTU_FROM_ROUTE(sctp_ifa, sa, rt) ((rt != NULL) ? rt->rt_rmx.rmx_mtu : 0)
343 #define SCTP_GATHER_MTU_FROM_INTFC(sctp_ifn) ((sctp_ifn->ifn_p != NULL) ? ((struct ifnet *)(sctp_ifn->ifn_p))->if_mtu : 0)
344 #define SCTP_SET_MTU_OF_ROUTE(sa, rt, mtu) do { \
345                                               if (rt != NULL) \
346                                                  rt->rt_rmx.rmx_mtu = mtu; \
347                                            } while(0)
348 
349 /* (de-)register interface event notifications */
350 #define SCTP_REGISTER_INTERFACE(ifhandle, af)
351 #define SCTP_DEREGISTER_INTERFACE(ifhandle, af)
352 
353 
354 /*************************/
355 /* These are for logging */
356 /*************************/
357 /* return the base ext data pointer */
358 #define SCTP_BUF_EXTEND_BASE(m) (m->m_ext.ext_buf)
359  /* return the refcnt of the data pointer */
360 #define SCTP_BUF_EXTEND_REFCNT(m) (*m->m_ext.ref_cnt)
361 /* return any buffer related flags, this is
362  * used beyond logging for apple only.
363  */
364 #define SCTP_BUF_GET_FLAGS(m) (m->m_flags)
365 
366 /* For BSD this just accesses the M_PKTHDR length
367  * so it operates on an mbuf with hdr flag. Other
368  * O/S's may have seperate packet header and mbuf
369  * chain pointers.. thus the macro.
370  */
371 #define SCTP_HEADER_TO_CHAIN(m) (m)
372 #define SCTP_DETACH_HEADER_FROM_CHAIN(m)
373 #define SCTP_HEADER_LEN(m) (m->m_pkthdr.len)
374 #define SCTP_GET_HEADER_FOR_OUTPUT(o_pak) 0
375 #define SCTP_RELEASE_HEADER(m)
376 #define SCTP_RELEASE_PKT(m)	sctp_m_freem(m)
377 #define SCTP_ENABLE_UDP_CSUM(m) do { \
378 					m->m_pkthdr.csum_flags = CSUM_UDP; \
379 					m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); \
380 				} while (0)
381 
382 #define SCTP_GET_PKT_VRFID(m, vrf_id)  ((vrf_id = SCTP_DEFAULT_VRFID) != SCTP_DEFAULT_VRFID)
383 
384 
385 
386 /* Attach the chain of data into the sendable packet. */
387 #define SCTP_ATTACH_CHAIN(pak, m, packet_length) do { \
388                                                  pak = m; \
389                                                  pak->m_pkthdr.len = packet_length; \
390                          } while(0)
391 
392 /* Other m_pkthdr type things */
393 #define SCTP_IS_IT_BROADCAST(dst, m) ((m->m_flags & M_PKTHDR) ? in_broadcast(dst, m->m_pkthdr.rcvif) : 0)
394 #define SCTP_IS_IT_LOOPBACK(m) ((m->m_flags & M_PKTHDR) && ((m->m_pkthdr.rcvif == NULL) || (m->m_pkthdr.rcvif->if_type == IFT_LOOP)))
395 
396 
397 /* This converts any input packet header
398  * into the chain of data holders, for BSD
399  * its a NOP.
400  */
401 
402 /* Macro's for getting length from V6/V4 header */
403 #define SCTP_GET_IPV4_LENGTH(iph) (iph->ip_len)
404 #define SCTP_GET_IPV6_LENGTH(ip6) (ntohs(ip6->ip6_plen))
405 
406 /* get the v6 hop limit */
407 #define SCTP_GET_HLIM(inp, ro)	in6_selecthlim((struct in6pcb *)&inp->ip_inp.inp, (ro ? (ro->ro_rt ? (ro->ro_rt->rt_ifp) : (NULL)) : (NULL)));
408 
409 /* is the endpoint v6only? */
410 #define SCTP_IPV6_V6ONLY(inp)	(((struct inpcb *)inp)->inp_flags & IN6P_IPV6_V6ONLY)
411 /* is the socket non-blocking? */
412 #define SCTP_SO_IS_NBIO(so)	((so)->so_state & SS_NBIO)
413 #define SCTP_SET_SO_NBIO(so)	((so)->so_state |= SS_NBIO)
414 #define SCTP_CLEAR_SO_NBIO(so)	((so)->so_state &= ~SS_NBIO)
415 /* get the socket type */
416 #define SCTP_SO_TYPE(so)	((so)->so_type)
417 /* reserve sb space for a socket */
418 #define SCTP_SORESERVE(so, send, recv)	soreserve(so, send, recv)
419 /* wakeup a socket */
420 #define SCTP_SOWAKEUP(so)	wakeup(&(so)->so_timeo)
421 /* clear the socket buffer state */
422 #define SCTP_SB_CLEAR(sb)	\
423 	(sb).sb_cc = 0;		\
424 	(sb).sb_mb = NULL;	\
425 	(sb).sb_mbcnt = 0;
426 
427 #define SCTP_SB_LIMIT_RCV(so) so->so_rcv.sb_hiwat
428 #define SCTP_SB_LIMIT_SND(so) so->so_snd.sb_hiwat
429 
430 /*
431  * routes, output, etc.
432  */
433 typedef struct route sctp_route_t;
434 typedef struct rtentry sctp_rtentry_t;
435 
436 #define SCTP_RTALLOC(ro, vrf_id) rtalloc_ign((struct route *)ro, 0UL)
437 
438 /* Future zero copy wakeup/send  function */
439 #define SCTP_ZERO_COPY_EVENT(inp, so)
440 /* This is re-pulse ourselves for sendbuf */
441 #define SCTP_ZERO_COPY_SENDQ_EVENT(inp, so)
442 
443 /*
444  * IP output routines
445  */
446 #define SCTP_IP_OUTPUT(result, o_pak, ro, stcb, vrf_id) \
447 { \
448 	int o_flgs = 0; \
449 	if (stcb && stcb->sctp_ep && stcb->sctp_ep->sctp_socket) { \
450 		o_flgs = IP_RAWOUTPUT | (stcb->sctp_ep->sctp_socket->so_options & SO_DONTROUTE); \
451 	} else { \
452 		o_flgs = IP_RAWOUTPUT; \
453 	} \
454 	result = ip_output(o_pak, NULL, ro, o_flgs, 0, NULL); \
455 }
456 
457 #define SCTP_IP6_OUTPUT(result, o_pak, ro, ifp, stcb, vrf_id) \
458 { \
459  	if (stcb && stcb->sctp_ep) \
460 		result = ip6_output(o_pak, \
461 				    ((struct in6pcb *)(stcb->sctp_ep))->in6p_outputopts, \
462 				    (ro), 0, 0, ifp, NULL); \
463 	else \
464 		result = ip6_output(o_pak, NULL, (ro), 0, 0, ifp, NULL); \
465 }
466 
467 struct mbuf *
468 sctp_get_mbuf_for_msg(unsigned int space_needed,
469     int want_header, int how, int allonebuf, int type);
470 
471 
472 /*
473  * SCTP AUTH
474  */
475 #define HAVE_SHA2
476 
477 #define SCTP_READ_RANDOM(buf, len)	read_random(buf, len)
478 
479 #ifdef USE_SCTP_SHA1
480 #include <netinet/sctp_sha1.h>
481 #else
482 #include <crypto/sha1.h>
483 /* map standard crypto API names */
484 #define SHA1_Init	SHA1Init
485 #define SHA1_Update	SHA1Update
486 #define SHA1_Final(x,y)	SHA1Final((caddr_t)x, y)
487 #endif
488 
489 #if defined(HAVE_SHA2)
490 #include <crypto/sha2/sha2.h>
491 #endif
492 
493 #include <sys/md5.h>
494 /* map standard crypto API names */
495 #define MD5_Init	MD5Init
496 #define MD5_Update	MD5Update
497 #define MD5_Final	MD5Final
498 
499 #endif
500 
501 #define SCTP_DECREMENT_AND_CHECK_REFCOUNT(addr) (atomic_fetchadd_int(addr, -1) == 1)
502 #if defined(INVARIANTS)
503 #define SCTP_SAVE_ATOMIC_DECREMENT(addr, val) \
504 { \
505 	int32_t oldval; \
506 	oldval = atomic_fetchadd_int(addr, -val); \
507 	if (oldval < val) { \
508 		panic("Counter goes negative"); \
509 	} \
510 }
511 #else
512 #define SCTP_SAVE_ATOMIC_DECREMENT(addr, val) \
513 { \
514 	int32_t oldval; \
515 	oldval = atomic_fetchadd_int(addr, -val); \
516 	if (oldval < val) { \
517 		*addr = 0; \
518 	} \
519 }
520 #endif
521