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#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include	<sys/types.h>
30#include	<sys/kmem.h>
31#include	<sys/bitmap.h>
32#include	<sys/stream.h>
33#include	<sys/strsubr.h>
34#define	_SUN_TPI_VERSION	2
35#include	<sys/tihdr.h>
36#include	<sys/suntpi.h>
37
38/*
39 * Hash table parameters for tpi_provinfo_table.
40 */
41#define	TPI_HASH_BITS	4
42#define	TPI_NHASH	(1 << TPI_HASH_BITS)
43
44/*
45 * Use the first element in the key for the hash.
46 */
47#define	TPI_HASH(p)	((((uintptr_t *)p)[0] >> tpi_hashshift) % TPI_NHASH)
48/*
49 * SAMESTR is a very confusing name. LAST_QUEUE is introduced for readability.
50 */
51#define	LAST_QUEUE(q)	(!SAMESTR(q))
52
53static tpi_provinfo_t	*tpi_provinfo_table[TPI_NHASH];
54static kmutex_t		tpi_provinfo_lock;
55static int		tpi_hashshift;
56
57/*
58 * In most cases there is some transport provider (like tcp or udp) below
59 * transport user (like timod or sockets). However, it is possible to construct
60 * stream without transport provider (e.g. by pushing timod into FIFO). It is
61 * hardly of any use, but this condition was observed with sparcv9 abi tests.
62 * To count for such special case, a special tpi_nullprov static data is
63 * provided to cache information about such degenerated null-transport case.
64 */
65static tpi_provinfo_t	tpi_nullprov;	/* Placeholder for null transport */
66
67/*
68 * Initialise the TPI support routines.  Called from strinit().
69 */
70void
71tpi_init()
72{
73	mutex_init(&tpi_provinfo_lock, NULL, MUTEX_DEFAULT, NULL);
74
75	/*
76	 * Calculate the right shift for hashing a tpi_provinfo_t.
77	 */
78	tpi_hashshift = highbit(sizeof (tpi_provinfo_t));
79}
80
81/*
82 * Generate a downstream signature given the write-side queue.  It
83 * passes back the size of the generated key in *keylenp.  This routine
84 * cannot multithread as it returns a pointer to a static data item.
85 *
86 * There is no way (in the current module loading infrastructure) to
87 * _absolutely_ guarantee that the key below uniquely identifies an
88 * arrangement of modules and drivers.  A module _might_ be unloaded and
89 * another module _might_ be loaded such that the qi_minfo is at _exactly_
90 * same kernel address, and then it _might_ be placed in a transport
91 * provider stream in exactly the same configuration (modules above and
92 * below all identical) - but it would take quite a few coincidences
93 * and modules loading and unloading does not usually happen n times a
94 * second...
95 */
96static void	*
97tpi_makekey(queue_t *q, size_t *keylenp)
98{
99	static uintptr_t	*key	= NULL;
100	int			i;
101
102	ASSERT(q != NULL);
103	ASSERT(MUTEX_HELD(&tpi_provinfo_lock));
104
105	/* assert this queue is write queue and qprocson() is called before */
106	ASSERT((q->q_flag & QREADR) == 0);
107	ASSERT(q->q_next != NULL);
108
109	/*
110	 * This can be global because tpi_makekey is called with
111	 * tpi_provinfo_lock.
112	 */
113	if (key == NULL)
114		key = kmem_alloc((nstrpush + 1) * sizeof (uintptr_t), KM_SLEEP);
115
116	ASSERT(key != NULL);
117
118	/*
119	 * Go down q_next to the driver, but no further.  We use the qi_minfo
120	 * because we can find in from the queue and it is a stable part of
121	 * any driver/module infrastructure.
122	 */
123	for (i = 0; !LAST_QUEUE(q) && (q = q->q_next) != NULL; ++i) {
124		ASSERT(i < nstrpush + 1);
125		key[i] = (uintptr_t)q->q_qinfo->qi_minfo;
126	}
127
128	/*
129	 * Allocate the actual key with the proper length, and pass it
130	 * all back.
131	 */
132	*keylenp = i * sizeof (uintptr_t);
133	return ((void *)key);
134}
135
136/*
137 * Find an existing provider entry given a queue pointer, or allocate a
138 * new empty entry if not found.  Because this routine calls kmem_alloc
139 * with KM_SLEEP, and because it traverses the q_next pointers of a stream
140 * it must be called with a proper user context and within a perimeter
141 * which protects the STREAM e.g. an open routine.  This routine always
142 * returns a valid pointer.
143 */
144tpi_provinfo_t	*
145tpi_findprov(queue_t *q)
146{
147	void		*key;
148	size_t		keylen;
149	tpi_provinfo_t	**tpp;
150
151	mutex_enter(&tpi_provinfo_lock);
152
153	/*
154	 * Must hold tpi_provinfo_lock since tpi_makekey() returns a pointer
155	 * to static data.
156	 */
157	key = tpi_makekey(WR(q), &keylen);
158
159	if (keylen == 0) {
160		/* there is nothing below us, return special nullprov entry */
161		mutex_exit(&tpi_provinfo_lock);
162		return (&tpi_nullprov);
163	}
164
165	/*
166	 * Look for an existing entry, or the place to put a new one.
167	 */
168	for (tpp = &tpi_provinfo_table[TPI_HASH(key)]; *tpp != NULL;
169	    tpp = &(*tpp)->tpi_next) {
170		if ((*tpp)->tpi_keylen == keylen &&
171		    bcmp((*tpp)->tpi_key, key, keylen) == 0) {
172			mutex_exit(&tpi_provinfo_lock);
173			return (*tpp);
174		}
175	}
176
177	/*
178	 * Allocate and fill in the new tpi_provinfo_t.
179	 */
180	*tpp = kmem_zalloc(sizeof (tpi_provinfo_t), KM_SLEEP);
181	(*tpp)->tpi_key = kmem_alloc(keylen, KM_SLEEP);
182	bcopy(key, (*tpp)->tpi_key, keylen);
183	(*tpp)->tpi_keylen = keylen;
184	mutex_init(&(*tpp)->tpi_lock, NULL, MUTEX_DEFAULT, NULL);
185
186	mutex_exit(&tpi_provinfo_lock);
187	return (*tpp);
188}
189
190/*
191 * Allocate a TPI ACK reusing the old message if possible.
192 */
193mblk_t	*
194tpi_ack_alloc(mblk_t *mp, size_t size, uchar_t db_type, t_scalar_t prim)
195{
196	mblk_t	*omp	= mp;
197
198	if ((mp = reallocb(mp, size, 0)) == NULL) {
199		freemsg(omp);
200		return (NULL);
201	}
202	if (mp->b_cont != NULL) {
203		freemsg(mp->b_cont);
204		mp->b_cont = NULL;
205	}
206	mp->b_datap->db_type = db_type;
207	mp->b_wptr = mp->b_rptr + size;
208	((union T_primitives *)mp->b_rptr)->type = prim;
209	return (mp);
210}
211