1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include <sys/types.h>
28 #include <sys/kmem.h>
29 #include <sys/bitmap.h>
30 #include <sys/stream.h>
31 #include <sys/strsubr.h>
32 #define _SUN_TPI_VERSION 2
33 #include <sys/tihdr.h>
34 #include <sys/suntpi.h>
35
36 /*
37 * Hash table parameters for tpi_provinfo_table.
38 */
39 #define TPI_HASH_BITS 4
40 #define TPI_NHASH (1 << TPI_HASH_BITS)
41
42 /*
43 * Use the first element in the key for the hash.
44 */
45 #define TPI_HASH(p) ((((uintptr_t *)p)[0] >> tpi_hashshift) % TPI_NHASH)
46 /*
47 * SAMESTR is a very confusing name. LAST_QUEUE is introduced for readability.
48 */
49 #define LAST_QUEUE(q) (!SAMESTR(q))
50
51 static tpi_provinfo_t *tpi_provinfo_table[TPI_NHASH];
52 static kmutex_t tpi_provinfo_lock;
53 static int tpi_hashshift;
54
55 /*
56 * In most cases there is some transport provider (like tcp or udp) below
57 * transport user (like timod or sockets). However, it is possible to construct
58 * stream without transport provider (e.g. by pushing timod into FIFO). It is
59 * hardly of any use, but this condition was observed with sparcv9 abi tests.
60 * To count for such special case, a special tpi_nullprov static data is
61 * provided to cache information about such degenerated null-transport case.
62 */
63 static tpi_provinfo_t tpi_nullprov; /* Placeholder for null transport */
64
65 /*
66 * Initialise the TPI support routines. Called from strinit().
67 */
68 void
tpi_init()69 tpi_init()
70 {
71 mutex_init(&tpi_provinfo_lock, NULL, MUTEX_DEFAULT, NULL);
72
73 /*
74 * Calculate the right shift for hashing a tpi_provinfo_t.
75 */
76 tpi_hashshift = highbit(sizeof (tpi_provinfo_t));
77 }
78
79 /*
80 * Generate a downstream signature given the write-side queue. It
81 * passes back the size of the generated key in *keylenp. This routine
82 * cannot multithread as it returns a pointer to a static data item.
83 *
84 * There is no way (in the current module loading infrastructure) to
85 * _absolutely_ guarantee that the key below uniquely identifies an
86 * arrangement of modules and drivers. A module _might_ be unloaded and
87 * another module _might_ be loaded such that the qi_minfo is at _exactly_
88 * same kernel address, and then it _might_ be placed in a transport
89 * provider stream in exactly the same configuration (modules above and
90 * below all identical) - but it would take quite a few coincidences
91 * and modules loading and unloading does not usually happen n times a
92 * second...
93 */
94 static void *
tpi_makekey(queue_t * q,size_t * keylenp)95 tpi_makekey(queue_t *q, size_t *keylenp)
96 {
97 static uintptr_t *key = NULL;
98 int i;
99
100 ASSERT(q != NULL);
101 ASSERT(MUTEX_HELD(&tpi_provinfo_lock));
102
103 /* assert this queue is write queue and qprocson() is called before */
104 ASSERT((q->q_flag & QREADR) == 0);
105 ASSERT(q->q_next != NULL);
106
107 /*
108 * This can be global because tpi_makekey is called with
109 * tpi_provinfo_lock.
110 */
111 if (key == NULL)
112 key = kmem_alloc((nstrpush + 1) * sizeof (uintptr_t), KM_SLEEP);
113
114 ASSERT(key != NULL);
115
116 /*
117 * Go down q_next to the driver, but no further. We use the qi_minfo
118 * because we can find in from the queue and it is a stable part of
119 * any driver/module infrastructure.
120 */
121 for (i = 0; !LAST_QUEUE(q) && (q = q->q_next) != NULL; ++i) {
122 ASSERT(i < nstrpush + 1);
123 key[i] = (uintptr_t)q->q_qinfo->qi_minfo;
124 }
125
126 /*
127 * Allocate the actual key with the proper length, and pass it
128 * all back.
129 */
130 *keylenp = i * sizeof (uintptr_t);
131 return ((void *)key);
132 }
133
134 /*
135 * Find an existing provider entry given a queue pointer, or allocate a
136 * new empty entry if not found. Because this routine calls kmem_alloc
137 * with KM_SLEEP, and because it traverses the q_next pointers of a stream
138 * it must be called with a proper user context and within a perimeter
139 * which protects the STREAM e.g. an open routine. This routine always
140 * returns a valid pointer.
141 */
142 tpi_provinfo_t *
tpi_findprov(queue_t * q)143 tpi_findprov(queue_t *q)
144 {
145 void *key;
146 size_t keylen;
147 tpi_provinfo_t **tpp;
148
149 mutex_enter(&tpi_provinfo_lock);
150
151 /*
152 * Must hold tpi_provinfo_lock since tpi_makekey() returns a pointer
153 * to static data.
154 */
155 key = tpi_makekey(WR(q), &keylen);
156
157 if (keylen == 0) {
158 /* there is nothing below us, return special nullprov entry */
159 mutex_exit(&tpi_provinfo_lock);
160 return (&tpi_nullprov);
161 }
162
163 /*
164 * Look for an existing entry, or the place to put a new one.
165 */
166 for (tpp = &tpi_provinfo_table[TPI_HASH(key)]; *tpp != NULL;
167 tpp = &(*tpp)->tpi_next) {
168 if ((*tpp)->tpi_keylen == keylen &&
169 bcmp((*tpp)->tpi_key, key, keylen) == 0) {
170 mutex_exit(&tpi_provinfo_lock);
171 return (*tpp);
172 }
173 }
174
175 /*
176 * Allocate and fill in the new tpi_provinfo_t.
177 */
178 *tpp = kmem_zalloc(sizeof (tpi_provinfo_t), KM_SLEEP);
179 (*tpp)->tpi_key = kmem_alloc(keylen, KM_SLEEP);
180 bcopy(key, (*tpp)->tpi_key, keylen);
181 (*tpp)->tpi_keylen = keylen;
182 mutex_init(&(*tpp)->tpi_lock, NULL, MUTEX_DEFAULT, NULL);
183
184 mutex_exit(&tpi_provinfo_lock);
185 return (*tpp);
186 }
187
188 /*
189 * Allocate a TPI ACK reusing the old message if possible.
190 */
191 mblk_t *
tpi_ack_alloc(mblk_t * mp,size_t size,uchar_t db_type,t_scalar_t prim)192 tpi_ack_alloc(mblk_t *mp, size_t size, uchar_t db_type, t_scalar_t prim)
193 {
194 mblk_t *omp = mp;
195
196 if ((mp = reallocb(mp, size, 0)) == NULL) {
197 freemsg(omp);
198 return (NULL);
199 }
200 if (mp->b_cont != NULL) {
201 freemsg(mp->b_cont);
202 mp->b_cont = NULL;
203 }
204 mp->b_datap->db_type = db_type;
205 mp->b_wptr = mp->b_rptr + size;
206 ((union T_primitives *)mp->b_rptr)->type = prim;
207 return (mp);
208 }
209