drivers: power: report battery voltage in AOSP compatible format
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / ioprio.c
1 /*
2 * fs/ioprio.c
3 *
4 * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
5 *
6 * Helper functions for setting/querying io priorities of processes. The
7 * system calls closely mimmick getpriority/setpriority, see the man page for
8 * those. The prio argument is a composite of prio class and prio data, where
9 * the data argument has meaning within that class. The standard scheduling
10 * classes have 8 distinct prio levels, with 0 being the highest prio and 7
11 * being the lowest.
12 *
13 * IOW, setting BE scheduling class with prio 2 is done ala:
14 *
15 * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
16 *
17 * ioprio_set(PRIO_PROCESS, pid, prio);
18 *
19 * See also Documentation/block/ioprio.txt
20 *
21 */
22 #include <linux/gfp.h>
23 #include <linux/kernel.h>
24 #include <linux/export.h>
25 #include <linux/ioprio.h>
26 #include <linux/blkdev.h>
27 #include <linux/capability.h>
28 #include <linux/syscalls.h>
29 #include <linux/security.h>
30 #include <linux/pid_namespace.h>
31
32 int set_task_ioprio(struct task_struct *task, int ioprio)
33 {
34 int err;
35 struct io_context *ioc;
36 const struct cred *cred = current_cred(), *tcred;
37
38 rcu_read_lock();
39 tcred = __task_cred(task);
40 if (!uid_eq(tcred->uid, cred->euid) &&
41 !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
42 rcu_read_unlock();
43 return -EPERM;
44 }
45 rcu_read_unlock();
46
47 err = security_task_setioprio(task, ioprio);
48 if (err)
49 return err;
50
51 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
52 if (ioc) {
53 ioc->ioprio = ioprio;
54 put_io_context(ioc);
55 }
56
57 return err;
58 }
59 EXPORT_SYMBOL_GPL(set_task_ioprio);
60
61 SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
62 {
63 int class = IOPRIO_PRIO_CLASS(ioprio);
64 int data = IOPRIO_PRIO_DATA(ioprio);
65 struct task_struct *p, *g;
66 struct user_struct *user;
67 struct pid *pgrp;
68 kuid_t uid;
69 int ret;
70
71 switch (class) {
72 case IOPRIO_CLASS_RT:
73 if (!capable(CAP_SYS_ADMIN))
74 return -EPERM;
75 /* fall through, rt has prio field too */
76 case IOPRIO_CLASS_BE:
77 if (data >= IOPRIO_BE_NR || data < 0)
78 return -EINVAL;
79
80 break;
81 case IOPRIO_CLASS_IDLE:
82 break;
83 case IOPRIO_CLASS_NONE:
84 if (data)
85 return -EINVAL;
86 break;
87 default:
88 return -EINVAL;
89 }
90
91 ret = -ESRCH;
92 rcu_read_lock();
93 switch (which) {
94 case IOPRIO_WHO_PROCESS:
95 if (!who)
96 p = current;
97 else
98 p = find_task_by_vpid(who);
99 if (p)
100 ret = set_task_ioprio(p, ioprio);
101 break;
102 case IOPRIO_WHO_PGRP:
103 if (!who)
104 pgrp = task_pgrp(current);
105 else
106 pgrp = find_vpid(who);
107 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
108 ret = set_task_ioprio(p, ioprio);
109 if (ret)
110 break;
111 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
112 break;
113 case IOPRIO_WHO_USER:
114 uid = make_kuid(current_user_ns(), who);
115 if (!uid_valid(uid))
116 break;
117 if (!who)
118 user = current_user();
119 else
120 user = find_user(uid);
121
122 if (!user)
123 break;
124
125 do_each_thread(g, p) {
126 if (!uid_eq(task_uid(p), uid))
127 continue;
128 ret = set_task_ioprio(p, ioprio);
129 if (ret)
130 goto free_uid;
131 } while_each_thread(g, p);
132 free_uid:
133 if (who)
134 free_uid(user);
135 break;
136 default:
137 ret = -EINVAL;
138 }
139
140 rcu_read_unlock();
141 return ret;
142 }
143
144 static int get_task_ioprio(struct task_struct *p)
145 {
146 int ret;
147
148 ret = security_task_getioprio(p);
149 if (ret)
150 goto out;
151 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
152 task_lock(p);
153 if (p->io_context)
154 ret = p->io_context->ioprio;
155 task_unlock(p);
156 out:
157 return ret;
158 }
159
160 int ioprio_best(unsigned short aprio, unsigned short bprio)
161 {
162 unsigned short aclass;
163 unsigned short bclass;
164
165 if (!ioprio_valid(aprio))
166 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
167 if (!ioprio_valid(bprio))
168 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
169
170 aclass = IOPRIO_PRIO_CLASS(aprio);
171 bclass = IOPRIO_PRIO_CLASS(bprio);
172 if (aclass == bclass)
173 return min(aprio, bprio);
174 if (aclass > bclass)
175 return bprio;
176 else
177 return aprio;
178 }
179
180 SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
181 {
182 struct task_struct *g, *p;
183 struct user_struct *user;
184 struct pid *pgrp;
185 kuid_t uid;
186 int ret = -ESRCH;
187 int tmpio;
188
189 rcu_read_lock();
190 switch (which) {
191 case IOPRIO_WHO_PROCESS:
192 if (!who)
193 p = current;
194 else
195 p = find_task_by_vpid(who);
196 if (p)
197 ret = get_task_ioprio(p);
198 break;
199 case IOPRIO_WHO_PGRP:
200 if (!who)
201 pgrp = task_pgrp(current);
202 else
203 pgrp = find_vpid(who);
204 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
205 tmpio = get_task_ioprio(p);
206 if (tmpio < 0)
207 continue;
208 if (ret == -ESRCH)
209 ret = tmpio;
210 else
211 ret = ioprio_best(ret, tmpio);
212 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
213 break;
214 case IOPRIO_WHO_USER:
215 uid = make_kuid(current_user_ns(), who);
216 if (!who)
217 user = current_user();
218 else
219 user = find_user(uid);
220
221 if (!user)
222 break;
223
224 do_each_thread(g, p) {
225 if (!uid_eq(task_uid(p), user->uid))
226 continue;
227 tmpio = get_task_ioprio(p);
228 if (tmpio < 0)
229 continue;
230 if (ret == -ESRCH)
231 ret = tmpio;
232 else
233 ret = ioprio_best(ret, tmpio);
234 } while_each_thread(g, p);
235
236 if (who)
237 free_uid(user);
238 break;
239 default:
240 ret = -EINVAL;
241 }
242
243 rcu_read_unlock();
244 return ret;
245 }