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Source at commit b05a5adf03613de371c77c3235f7d970d7cd0c71 created 13 years 1 month ago. By Lars-Peter Clausen, NAND: Optimize reading the eec data for the JZ4740 (evil hack) | |
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1 | /* |
2 | * fs/signalfd.c |
3 | * |
4 | * Copyright (C) 2003 Linus Torvalds |
5 | * |
6 | * Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org> |
7 | * Changed ->read() to return a siginfo strcture instead of signal number. |
8 | * Fixed locking in ->poll(). |
9 | * Added sighand-detach notification. |
10 | * Added fd re-use in sys_signalfd() syscall. |
11 | * Now using anonymous inode source. |
12 | * Thanks to Oleg Nesterov for useful code review and suggestions. |
13 | * More comments and suggestions from Arnd Bergmann. |
14 | * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br> |
15 | * Retrieve multiple signals with one read() call |
16 | * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org> |
17 | * Attach to the sighand only during read() and poll(). |
18 | */ |
19 | |
20 | #include <linux/file.h> |
21 | #include <linux/poll.h> |
22 | #include <linux/init.h> |
23 | #include <linux/fs.h> |
24 | #include <linux/sched.h> |
25 | #include <linux/slab.h> |
26 | #include <linux/kernel.h> |
27 | #include <linux/signal.h> |
28 | #include <linux/list.h> |
29 | #include <linux/anon_inodes.h> |
30 | #include <linux/signalfd.h> |
31 | #include <linux/syscalls.h> |
32 | |
33 | struct signalfd_ctx { |
34 | sigset_t sigmask; |
35 | }; |
36 | |
37 | static int signalfd_release(struct inode *inode, struct file *file) |
38 | { |
39 | kfree(file->private_data); |
40 | return 0; |
41 | } |
42 | |
43 | static unsigned int signalfd_poll(struct file *file, poll_table *wait) |
44 | { |
45 | struct signalfd_ctx *ctx = file->private_data; |
46 | unsigned int events = 0; |
47 | |
48 | poll_wait(file, ¤t->sighand->signalfd_wqh, wait); |
49 | |
50 | spin_lock_irq(¤t->sighand->siglock); |
51 | if (next_signal(¤t->pending, &ctx->sigmask) || |
52 | next_signal(¤t->signal->shared_pending, |
53 | &ctx->sigmask)) |
54 | events |= POLLIN; |
55 | spin_unlock_irq(¤t->sighand->siglock); |
56 | |
57 | return events; |
58 | } |
59 | |
60 | /* |
61 | * Copied from copy_siginfo_to_user() in kernel/signal.c |
62 | */ |
63 | static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo, |
64 | siginfo_t const *kinfo) |
65 | { |
66 | long err; |
67 | |
68 | BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128); |
69 | |
70 | /* |
71 | * Unused members should be zero ... |
72 | */ |
73 | err = __clear_user(uinfo, sizeof(*uinfo)); |
74 | |
75 | /* |
76 | * If you change siginfo_t structure, please be sure |
77 | * this code is fixed accordingly. |
78 | */ |
79 | err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo); |
80 | err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno); |
81 | err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code); |
82 | switch (kinfo->si_code & __SI_MASK) { |
83 | case __SI_KILL: |
84 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
85 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); |
86 | break; |
87 | case __SI_TIMER: |
88 | err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid); |
89 | err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun); |
90 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); |
91 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); |
92 | break; |
93 | case __SI_POLL: |
94 | err |= __put_user(kinfo->si_band, &uinfo->ssi_band); |
95 | err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd); |
96 | break; |
97 | case __SI_FAULT: |
98 | err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr); |
99 | #ifdef __ARCH_SI_TRAPNO |
100 | err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno); |
101 | #endif |
102 | #ifdef BUS_MCEERR_AO |
103 | /* |
104 | * Other callers might not initialize the si_lsb field, |
105 | * so check explicitly for the right codes here. |
106 | */ |
107 | if (kinfo->si_code == BUS_MCEERR_AR || |
108 | kinfo->si_code == BUS_MCEERR_AO) |
109 | err |= __put_user((short) kinfo->si_addr_lsb, |
110 | &uinfo->ssi_addr_lsb); |
111 | #endif |
112 | break; |
113 | case __SI_CHLD: |
114 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
115 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); |
116 | err |= __put_user(kinfo->si_status, &uinfo->ssi_status); |
117 | err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime); |
118 | err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime); |
119 | break; |
120 | case __SI_RT: /* This is not generated by the kernel as of now. */ |
121 | case __SI_MESGQ: /* But this is */ |
122 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
123 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); |
124 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); |
125 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); |
126 | break; |
127 | default: |
128 | /* |
129 | * This case catches also the signals queued by sigqueue(). |
130 | */ |
131 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
132 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); |
133 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); |
134 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); |
135 | break; |
136 | } |
137 | |
138 | return err ? -EFAULT: sizeof(*uinfo); |
139 | } |
140 | |
141 | static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info, |
142 | int nonblock) |
143 | { |
144 | ssize_t ret; |
145 | DECLARE_WAITQUEUE(wait, current); |
146 | |
147 | spin_lock_irq(¤t->sighand->siglock); |
148 | ret = dequeue_signal(current, &ctx->sigmask, info); |
149 | switch (ret) { |
150 | case 0: |
151 | if (!nonblock) |
152 | break; |
153 | ret = -EAGAIN; |
154 | default: |
155 | spin_unlock_irq(¤t->sighand->siglock); |
156 | return ret; |
157 | } |
158 | |
159 | add_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
160 | for (;;) { |
161 | set_current_state(TASK_INTERRUPTIBLE); |
162 | ret = dequeue_signal(current, &ctx->sigmask, info); |
163 | if (ret != 0) |
164 | break; |
165 | if (signal_pending(current)) { |
166 | ret = -ERESTARTSYS; |
167 | break; |
168 | } |
169 | spin_unlock_irq(¤t->sighand->siglock); |
170 | schedule(); |
171 | spin_lock_irq(¤t->sighand->siglock); |
172 | } |
173 | spin_unlock_irq(¤t->sighand->siglock); |
174 | |
175 | remove_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
176 | __set_current_state(TASK_RUNNING); |
177 | |
178 | return ret; |
179 | } |
180 | |
181 | /* |
182 | * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative |
183 | * error code. The "count" parameter must be at least the size of a |
184 | * "struct signalfd_siginfo". |
185 | */ |
186 | static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count, |
187 | loff_t *ppos) |
188 | { |
189 | struct signalfd_ctx *ctx = file->private_data; |
190 | struct signalfd_siginfo __user *siginfo; |
191 | int nonblock = file->f_flags & O_NONBLOCK; |
192 | ssize_t ret, total = 0; |
193 | siginfo_t info; |
194 | |
195 | count /= sizeof(struct signalfd_siginfo); |
196 | if (!count) |
197 | return -EINVAL; |
198 | |
199 | siginfo = (struct signalfd_siginfo __user *) buf; |
200 | do { |
201 | ret = signalfd_dequeue(ctx, &info, nonblock); |
202 | if (unlikely(ret <= 0)) |
203 | break; |
204 | ret = signalfd_copyinfo(siginfo, &info); |
205 | if (ret < 0) |
206 | break; |
207 | siginfo++; |
208 | total += ret; |
209 | nonblock = 1; |
210 | } while (--count); |
211 | |
212 | return total ? total: ret; |
213 | } |
214 | |
215 | static const struct file_operations signalfd_fops = { |
216 | .release = signalfd_release, |
217 | .poll = signalfd_poll, |
218 | .read = signalfd_read, |
219 | .llseek = noop_llseek, |
220 | }; |
221 | |
222 | SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask, |
223 | size_t, sizemask, int, flags) |
224 | { |
225 | sigset_t sigmask; |
226 | struct signalfd_ctx *ctx; |
227 | |
228 | /* Check the SFD_* constants for consistency. */ |
229 | BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC); |
230 | BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK); |
231 | |
232 | if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK)) |
233 | return -EINVAL; |
234 | |
235 | if (sizemask != sizeof(sigset_t) || |
236 | copy_from_user(&sigmask, user_mask, sizeof(sigmask))) |
237 | return -EINVAL; |
238 | sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); |
239 | signotset(&sigmask); |
240 | |
241 | if (ufd == -1) { |
242 | ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); |
243 | if (!ctx) |
244 | return -ENOMEM; |
245 | |
246 | ctx->sigmask = sigmask; |
247 | |
248 | /* |
249 | * When we call this, the initialization must be complete, since |
250 | * anon_inode_getfd() will install the fd. |
251 | */ |
252 | ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx, |
253 | O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK))); |
254 | if (ufd < 0) |
255 | kfree(ctx); |
256 | } else { |
257 | struct file *file = fget(ufd); |
258 | if (!file) |
259 | return -EBADF; |
260 | ctx = file->private_data; |
261 | if (file->f_op != &signalfd_fops) { |
262 | fput(file); |
263 | return -EINVAL; |
264 | } |
265 | spin_lock_irq(¤t->sighand->siglock); |
266 | ctx->sigmask = sigmask; |
267 | spin_unlock_irq(¤t->sighand->siglock); |
268 | |
269 | wake_up(¤t->sighand->signalfd_wqh); |
270 | fput(file); |
271 | } |
272 | |
273 | return ufd; |
274 | } |
275 | |
276 | SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask, |
277 | size_t, sizemask) |
278 | { |
279 | return sys_signalfd4(ufd, user_mask, sizemask, 0); |
280 | } |
281 |
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