Disallow writes to filesystems mounted read-only via NULLFS. In this case
[dragonfly.git] / sys / kern / kern_usched.c
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1/*
2 * Copyright (c) 2005 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Sergey Glushchenko <deen@smz.com.ua>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
bc01a404 34 * $DragonFly: src/sys/kern/kern_usched.c,v 1.6 2006/09/03 17:43:59 dillon Exp $
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35 */
36
37#include <sys/errno.h>
38#include <sys/globaldata.h> /* curthread */
39#include <sys/proc.h>
40#include <sys/sysproto.h> /* struct usched_set_args */
41#include <sys/systm.h> /* strcmp() */
42#include <sys/usched.h>
a60ccb85 43#include <machine/smp.h>
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44
45static TAILQ_HEAD(, usched) usched_list = TAILQ_HEAD_INITIALIZER(usched_list);
46
47/*
48 * Called from very low level boot code, i386/i386/machdep.c/init386().
49 * We cannot do anything fancy. no malloc's, no nothing other then
50 * static initialization.
51 */
52struct usched *
53usched_init(void)
54{
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55 const char *defsched;
56
bc01a404 57 defsched = kgetenv("kern.user_scheduler");
52eedfb5 58
cb7f4ab1 59 /*
52eedfb5 60 * Add various userland schedulers to the system.
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61 */
62 usched_ctl(&usched_bsd4, USCH_ADD);
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63 usched_ctl(&usched_dummy, USCH_ADD);
64 if (defsched == NULL )
65 return(&usched_bsd4);
66 if (strcmp(defsched, "bsd4") == 0)
67 return(&usched_bsd4);
68 printf("WARNING: Running dummy userland scheduler\n");
69 return(&usched_dummy);
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70}
71
72/*
73 * USCHED_CTL
74 *
75 * SYNOPSIS:
76 * Add/remove usched to/from list.
77 *
78 * ARGUMENTS:
79 * usched - pointer to target scheduler
80 * action - addition or removal ?
81 *
82 * RETURN VALUES:
83 * 0 - success
84 * EINVAL - error
85 */
86int
87usched_ctl(struct usched *usched, int action)
88{
89 struct usched *item; /* temporaly for TAILQ processing */
90 int error = 0;
91
92 switch(action) {
93 case USCH_ADD:
94 /*
95 * Make sure it isn't already on the list
96 */
97#ifdef INVARIANTS
98 TAILQ_FOREACH(item, &usched_list, entry) {
99 KKASSERT(item != usched);
100 }
101#endif
102 /*
103 * Optional callback to the scheduler before we officially
104 * add it to the list.
105 */
106 if (usched->usched_register)
107 usched->usched_register();
108 TAILQ_INSERT_TAIL(&usched_list, usched, entry);
109 break;
110 case USCH_REM:
111 /*
112 * Do not allow the default scheduler to be removed
113 */
114 if (strcmp(usched->name, "bsd4") == 0) {
115 error = EINVAL;
116 break;
117 }
118 TAILQ_FOREACH(item, &usched_list, entry) {
119 if (item == usched)
120 break;
121 }
122 if (item) {
123 if (item->usched_unregister)
124 item->usched_unregister();
125 TAILQ_REMOVE(&usched_list, item, entry);
126 } else {
127 error = EINVAL;
128 }
129 break;
130 default:
131 error = EINVAL;
132 break;
133 }
134 return (error);
135}
136
137/*
138 * USCHED_SET(syscall)
139 *
140 * SYNOPSIS:
141 * Setting up a proc's usched.
142 *
143 * ARGUMENTS:
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144 * pid -
145 * cmd -
146 * data -
147 * bytes -
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148 * RETURN VALUES:
149 * 0 - success
150 * EINVAL - error
151 */
152int
753fd850 153sys_usched_set(struct usched_set_args *uap)
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154{
155 struct proc *p = curthread->td_proc;
156 struct usched *item; /* temporaly for TAILQ processing */
157 int error;
1b31454e 158 char buffer[NAME_LENGTH];
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159 cpumask_t mask;
160 struct lwp *lp;
161 int cpuid;
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162
163 if ((error = suser(curthread)) != 0)
164 return (error);
1b31454e 165
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166 if (uap->pid != 0 && uap->pid != curthread->td_proc->p_pid)
167 return (EINVAL);
cb7f4ab1 168
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169 lp = curthread->td_lwp;
170 switch (uap->cmd) {
171 case USCHED_SET_SCHEDULER:
172 if ((error = copyinstr(uap->data, buffer, sizeof(buffer),
173 NULL)) != 0)
174 return (error);
175 TAILQ_FOREACH(item, &usched_list, entry) {
176 if ((strcmp(item->name, buffer) == 0))
177 break;
178 }
179
180 /*
181 * If the scheduler for a process is being changed, disassociate
182 * the old scheduler before switching to the new one.
183 *
184 * XXX we might have to add an additional ABI call to do a 'full
185 * disassociation' and another ABI call to do a 'full
186 * reassociation'
187 */
188 if (item && item != p->p_usched) {
189 p->p_usched->release_curproc(&p->p_lwp);
190 p->p_usched = item;
191 } else if (item == NULL) {
192 error = EINVAL;
193 }
194 break;
195 case USCHED_SET_CPU:
196 if (uap->bytes != sizeof(int))
197 return (EINVAL);
198 error = copyin(uap->data, &cpuid, sizeof(int));
199 if (error)
200 break;
201 if ((smp_active_mask & (1 << cpuid)) == 0) {
202 error = EINVAL;
203 break;
204 }
205 lp->lwp_cpumask = 1 << cpuid;
206 if (cpuid != mycpu->gd_cpuid)
207 lwkt_migratecpu(cpuid);
208 break;
209 case USCHED_ADD_CPU:
210 if (uap->bytes != sizeof(int))
211 return (EINVAL);
212 error = copyin(uap->data, &cpuid, sizeof(int));
213 if (error)
214 break;
215 if (!(smp_active_mask & (1 << cpuid))) {
216 error = EINVAL;
217 break;
218 }
219 lp->lwp_cpumask |= 1 << cpuid;
220 break;
221 case USCHED_DEL_CPU:
222 if (uap->bytes != sizeof(int))
223 return (EINVAL);
224 error = copyin(uap->data, &cpuid, sizeof(int));
225 if (error)
226 break;
227 lp = curthread->td_lwp;
228 mask = lp->lwp_cpumask & smp_active_mask & ~(1 << cpuid);
229 if (mask == 0)
230 error = EPERM;
231 else {
232 lp->lwp_cpumask &= ~(1 << cpuid);
233 if ((lp->lwp_cpumask & mycpu->gd_cpumask) == 0) {
234 cpuid = bsfl(lp->lwp_cpumask & smp_active_mask);
235 lwkt_migratecpu(cpuid);
236 }
237 }
238 default:
cb7f4ab1 239 error = EINVAL;
a60ccb85 240 break;
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241 }
242 return (error);
243}
244