xref: /illumos-gate/usr/src/lib/libc/port/threads/pthread.c (revision ab618543cc6fc4bc273c077ef5d247961cdb29d4)
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 (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 /*
27  * Copyright 2018 Joyent, Inc.
28  */
29 
30 #include "lint.h"
31 #include "thr_uberdata.h"
32 
33 /*
34  * pthread_once related data
35  * This structure is exported as pthread_once_t in pthread.h.
36  * We export only the size of this structure. so check
37  * pthread_once_t in pthread.h before making a change here.
38  */
39 typedef struct  __once {
40 	mutex_t	mlock;
41 	union {
42 		uint32_t	pad32_flag[2];
43 		uint64_t	pad64_flag;
44 	} oflag;
45 } __once_t;
46 
47 #define	once_flag	oflag.pad32_flag[1]
48 
49 static int
50 _thr_setinherit(pthread_t tid, int inherit)
51 {
52 	ulwp_t *ulwp;
53 	int error = 0;
54 
55 	if ((ulwp = find_lwp(tid)) == NULL) {
56 		error = ESRCH;
57 	} else {
58 		ulwp->ul_ptinherit = inherit;
59 		ulwp_unlock(ulwp, curthread->ul_uberdata);
60 	}
61 
62 	return (error);
63 }
64 
65 static int
66 _thr_setparam(pthread_t tid, int policy, int prio)
67 {
68 	ulwp_t *ulwp;
69 	id_t cid;
70 	int error = 0;
71 
72 	if ((ulwp = find_lwp(tid)) == NULL) {
73 		error = ESRCH;
74 	} else {
75 		if (policy == ulwp->ul_policy &&
76 		    (policy == SCHED_FIFO || policy == SCHED_RR) &&
77 		    ulwp->ul_epri != 0) {
78 			/*
79 			 * Don't change the ceiling priority,
80 			 * just the base priority.
81 			 */
82 			if (prio > ulwp->ul_epri)
83 				error = EPERM;
84 			else
85 				ulwp->ul_pri = prio;
86 		} else if ((cid = setparam(P_LWPID, tid, policy, prio)) == -1) {
87 			error = errno;
88 		} else {
89 			if (policy == SCHED_FIFO || policy == SCHED_RR)
90 				ulwp->ul_rtclassid = cid;
91 			ulwp->ul_cid = cid;
92 			ulwp->ul_pri = prio;
93 			membar_producer();
94 			ulwp->ul_policy = policy;
95 		}
96 		ulwp_unlock(ulwp, curthread->ul_uberdata);
97 	}
98 	return (error);
99 }
100 
101 /*
102  * pthread_create: creates a thread in the current process.
103  * calls common _thrp_create() after copying the attributes.
104  */
105 #pragma weak _pthread_create = pthread_create
106 int
107 pthread_create(pthread_t *thread, const pthread_attr_t *attr,
108     void * (*start_routine)(void *), void *arg)
109 {
110 	ulwp_t		*self = curthread;
111 	const thrattr_t	*ap = attr? attr->__pthread_attrp : def_thrattr();
112 	const pcclass_t	*pccp;
113 	long		flag;
114 	pthread_t	tid;
115 	int		error;
116 
117 	update_sched(self);
118 
119 	if (ap == NULL)
120 		return (EINVAL);
121 
122 	/* validate explicit scheduling attributes */
123 	if (ap->inherit == PTHREAD_EXPLICIT_SCHED &&
124 	    (ap->policy == SCHED_SYS ||
125 	    (pccp = get_info_by_policy(ap->policy)) == NULL ||
126 	    ap->prio < pccp->pcc_primin || ap->prio > pccp->pcc_primax))
127 		return (EINVAL);
128 
129 	flag = ap->scope | ap->detachstate | ap->daemonstate | THR_SUSPENDED;
130 	error = _thrp_create(ap->stkaddr, ap->stksize, start_routine, arg,
131 	    flag, &tid, ap->guardsize, ap->name);
132 	if (error == 0) {
133 		/*
134 		 * Record the original inheritence value for
135 		 * pthread_getattr_np(). We should always be able to find the
136 		 * thread.
137 		 */
138 		(void) _thr_setinherit(tid, ap->inherit);
139 
140 		if (ap->inherit == PTHREAD_EXPLICIT_SCHED &&
141 		    (ap->policy != self->ul_policy ||
142 		    ap->prio != (self->ul_epri ? self->ul_epri :
143 		    self->ul_pri))) {
144 			/*
145 			 * The SUSv3 specification requires pthread_create()
146 			 * to fail with EPERM if it cannot set the scheduling
147 			 * policy and parameters on the new thread.
148 			 */
149 			error = _thr_setparam(tid, ap->policy, ap->prio);
150 		}
151 
152 		if (error) {
153 			/*
154 			 * We couldn't determine this error before
155 			 * actually creating the thread.  To recover,
156 			 * mark the thread detached and cancel it.
157 			 * It is as though it was never created.
158 			 */
159 			ulwp_t *ulwp = find_lwp(tid);
160 			if (ulwp->ul_detached == 0) {
161 				ulwp->ul_detached = 1;
162 				ulwp->ul_usropts |= THR_DETACHED;
163 				(void) __lwp_detach(tid);
164 			}
165 			ulwp->ul_cancel_pending = 2; /* cancelled on creation */
166 			ulwp->ul_cancel_disabled = 0;
167 			ulwp_unlock(ulwp, self->ul_uberdata);
168 		} else if (thread) {
169 			*thread = tid;
170 		}
171 		(void) thr_continue(tid);
172 	}
173 
174 	/* posix version expects EAGAIN for lack of memory */
175 	if (error == ENOMEM)
176 		error = EAGAIN;
177 	return (error);
178 }
179 
180 /*
181  * pthread_once: calls given function only once.
182  * it synchronizes via mutex in pthread_once_t structure
183  */
184 int
185 pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
186 {
187 	__once_t *once = (__once_t *)once_control;
188 
189 	if (once == NULL || init_routine == NULL)
190 		return (EINVAL);
191 
192 	if (once->once_flag == PTHREAD_ONCE_NOTDONE) {
193 		(void) mutex_lock(&once->mlock);
194 		if (once->once_flag == PTHREAD_ONCE_NOTDONE) {
195 			pthread_cleanup_push(mutex_unlock, &once->mlock);
196 			(*init_routine)();
197 			pthread_cleanup_pop(0);
198 			membar_producer();
199 			once->once_flag = PTHREAD_ONCE_DONE;
200 		}
201 		(void) mutex_unlock(&once->mlock);
202 	}
203 	membar_consumer();
204 
205 	return (0);
206 }
207 
208 /*
209  * pthread_equal: equates two thread ids.
210  */
211 int
212 pthread_equal(pthread_t t1, pthread_t t2)
213 {
214 	return (t1 == t2);
215 }
216 
217 /*
218  * pthread_getschedparam: get the thread's sched parameters.
219  */
220 #pragma weak _pthread_getschedparam = pthread_getschedparam
221 int
222 pthread_getschedparam(pthread_t tid, int *policy, struct sched_param *param)
223 {
224 	ulwp_t *ulwp;
225 	id_t cid;
226 	int error = 0;
227 
228 	if ((ulwp = find_lwp(tid)) == NULL) {
229 		error = ESRCH;
230 	} else {
231 		cid = getparam(P_LWPID, ulwp->ul_lwpid, policy, param);
232 		if (cid == -1) {
233 			error = errno;
234 		} else if (*policy == ulwp->ul_policy && cid == ulwp->ul_cid &&
235 		    (*policy == SCHED_FIFO || *policy == SCHED_RR)) {
236 			/*
237 			 * Return the defined priority, not the effective
238 			 * priority from priority ceiling mutexes.
239 			 */
240 			param->sched_priority = ulwp->ul_pri;
241 		} else {
242 			if (*policy == SCHED_FIFO || *policy == SCHED_RR)
243 				ulwp->ul_rtclassid = cid;
244 			ulwp->ul_cid = cid;
245 			ulwp->ul_pri = param->sched_priority;
246 			membar_producer();
247 			ulwp->ul_policy = *policy;
248 		}
249 		ulwp_unlock(ulwp, curthread->ul_uberdata);
250 	}
251 
252 	return (error);
253 }
254 
255 #pragma weak _thr_getprio = thr_getprio
256 int
257 thr_getprio(thread_t tid, int *priority)
258 {
259 	struct sched_param param;
260 	int policy;
261 	int error;
262 
263 	if ((error = pthread_getschedparam(tid, &policy, &param)) == 0)
264 		*priority = param.sched_priority;
265 	return (error);
266 }
267 
268 /*
269  * pthread_setschedparam: sets the sched parameters for a thread.
270  */
271 int
272 pthread_setschedparam(pthread_t tid,
273     int policy, const struct sched_param *param)
274 {
275 	return (_thr_setparam(tid, policy, param->sched_priority));
276 }
277 
278 #pragma weak pthread_setschedprio = thr_setprio
279 int
280 thr_setprio(thread_t tid, int prio)
281 {
282 	struct sched_param param;
283 	int policy;
284 	int error;
285 
286 	/*
287 	 * pthread_getschedparam() has the side-effect of setting
288 	 * the target thread's ul_policy, ul_pri and ul_cid correctly.
289 	 */
290 	if ((error = pthread_getschedparam(tid, &policy, &param)) != 0)
291 		return (error);
292 	if (param.sched_priority == prio)	/* no change */
293 		return (0);
294 	return (_thr_setparam(tid, policy, prio));
295 }
296