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Davide Libenzifba2afa2007-05-10 22:23:13 -07001/*
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.
Davide Libenzib8fceee2007-09-20 12:40:16 -070014 * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
Davi Arnautb3762bf2007-05-23 13:58:04 -070015 * Retrieve multiple signals with one read() call
Davide Libenzib8fceee2007-09-20 12:40:16 -070016 * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
17 * Attach to the sighand only during read() and poll().
Davide Libenzifba2afa2007-05-10 22:23:13 -070018 */
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/kernel.h>
26#include <linux/signal.h>
27#include <linux/list.h>
28#include <linux/anon_inodes.h>
29#include <linux/signalfd.h>
30
31struct signalfd_ctx {
Davide Libenzifba2afa2007-05-10 22:23:13 -070032 sigset_t sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -070033};
34
Davide Libenzifba2afa2007-05-10 22:23:13 -070035static int signalfd_release(struct inode *inode, struct file *file)
36{
Davide Libenzib8fceee2007-09-20 12:40:16 -070037 kfree(file->private_data);
Davide Libenzifba2afa2007-05-10 22:23:13 -070038 return 0;
39}
40
41static unsigned int signalfd_poll(struct file *file, poll_table *wait)
42{
43 struct signalfd_ctx *ctx = file->private_data;
44 unsigned int events = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -070045
Davide Libenzib8fceee2007-09-20 12:40:16 -070046 poll_wait(file, &current->sighand->signalfd_wqh, wait);
Davide Libenzifba2afa2007-05-10 22:23:13 -070047
Davide Libenzib8fceee2007-09-20 12:40:16 -070048 spin_lock_irq(&current->sighand->siglock);
49 if (next_signal(&current->pending, &ctx->sigmask) ||
50 next_signal(&current->signal->shared_pending,
51 &ctx->sigmask))
Davide Libenzifba2afa2007-05-10 22:23:13 -070052 events |= POLLIN;
Davide Libenzib8fceee2007-09-20 12:40:16 -070053 spin_unlock_irq(&current->sighand->siglock);
Davide Libenzifba2afa2007-05-10 22:23:13 -070054
55 return events;
56}
57
58/*
59 * Copied from copy_siginfo_to_user() in kernel/signal.c
60 */
61static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
62 siginfo_t const *kinfo)
63{
64 long err;
65
66 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
67
68 /*
69 * Unused memebers should be zero ...
70 */
71 err = __clear_user(uinfo, sizeof(*uinfo));
72
73 /*
74 * If you change siginfo_t structure, please be sure
75 * this code is fixed accordingly.
76 */
77 err |= __put_user(kinfo->si_signo, &uinfo->signo);
78 err |= __put_user(kinfo->si_errno, &uinfo->err);
79 err |= __put_user((short)kinfo->si_code, &uinfo->code);
80 switch (kinfo->si_code & __SI_MASK) {
81 case __SI_KILL:
82 err |= __put_user(kinfo->si_pid, &uinfo->pid);
83 err |= __put_user(kinfo->si_uid, &uinfo->uid);
84 break;
85 case __SI_TIMER:
86 err |= __put_user(kinfo->si_tid, &uinfo->tid);
87 err |= __put_user(kinfo->si_overrun, &uinfo->overrun);
88 err |= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
89 break;
90 case __SI_POLL:
91 err |= __put_user(kinfo->si_band, &uinfo->band);
92 err |= __put_user(kinfo->si_fd, &uinfo->fd);
93 break;
94 case __SI_FAULT:
95 err |= __put_user((long)kinfo->si_addr, &uinfo->addr);
96#ifdef __ARCH_SI_TRAPNO
97 err |= __put_user(kinfo->si_trapno, &uinfo->trapno);
98#endif
99 break;
100 case __SI_CHLD:
101 err |= __put_user(kinfo->si_pid, &uinfo->pid);
102 err |= __put_user(kinfo->si_uid, &uinfo->uid);
103 err |= __put_user(kinfo->si_status, &uinfo->status);
104 err |= __put_user(kinfo->si_utime, &uinfo->utime);
105 err |= __put_user(kinfo->si_stime, &uinfo->stime);
106 break;
107 case __SI_RT: /* This is not generated by the kernel as of now. */
108 case __SI_MESGQ: /* But this is */
109 err |= __put_user(kinfo->si_pid, &uinfo->pid);
110 err |= __put_user(kinfo->si_uid, &uinfo->uid);
111 err |= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
112 break;
113 default: /* this is just in case for now ... */
114 err |= __put_user(kinfo->si_pid, &uinfo->pid);
115 err |= __put_user(kinfo->si_uid, &uinfo->uid);
116 break;
117 }
118
119 return err ? -EFAULT: sizeof(*uinfo);
120}
121
Davi Arnautb3762bf2007-05-23 13:58:04 -0700122static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
123 int nonblock)
124{
125 ssize_t ret;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700126 DECLARE_WAITQUEUE(wait, current);
127
Davide Libenzib8fceee2007-09-20 12:40:16 -0700128 spin_lock_irq(&current->sighand->siglock);
129 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700130 switch (ret) {
131 case 0:
132 if (!nonblock)
133 break;
134 ret = -EAGAIN;
135 default:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700136 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700137 return ret;
138 }
139
Davide Libenzib8fceee2007-09-20 12:40:16 -0700140 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700141 for (;;) {
142 set_current_state(TASK_INTERRUPTIBLE);
Davide Libenzib8fceee2007-09-20 12:40:16 -0700143 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700144 if (ret != 0)
145 break;
146 if (signal_pending(current)) {
147 ret = -ERESTARTSYS;
148 break;
149 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700150 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700151 schedule();
Davide Libenzib8fceee2007-09-20 12:40:16 -0700152 spin_lock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700153 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700154 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700155
Davide Libenzib8fceee2007-09-20 12:40:16 -0700156 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700157 __set_current_state(TASK_RUNNING);
158
159 return ret;
160}
161
Davide Libenzifba2afa2007-05-10 22:23:13 -0700162/*
Davide Libenzib8fceee2007-09-20 12:40:16 -0700163 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
164 * error code. The "count" parameter must be at least the size of a
165 * "struct signalfd_siginfo".
Davide Libenzifba2afa2007-05-10 22:23:13 -0700166 */
167static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
168 loff_t *ppos)
169{
170 struct signalfd_ctx *ctx = file->private_data;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700171 struct signalfd_siginfo __user *siginfo;
172 int nonblock = file->f_flags & O_NONBLOCK;
173 ssize_t ret, total = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700174 siginfo_t info;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700175
Davi Arnautb3762bf2007-05-23 13:58:04 -0700176 count /= sizeof(struct signalfd_siginfo);
177 if (!count)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700178 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700179
Davi Arnautb3762bf2007-05-23 13:58:04 -0700180 siginfo = (struct signalfd_siginfo __user *) buf;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700181 do {
182 ret = signalfd_dequeue(ctx, &info, nonblock);
183 if (unlikely(ret <= 0))
184 break;
185 ret = signalfd_copyinfo(siginfo, &info);
186 if (ret < 0)
187 break;
188 siginfo++;
189 total += ret;
190 nonblock = 1;
191 } while (--count);
192
Davide Libenzib8fceee2007-09-20 12:40:16 -0700193 return total ? total: ret;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700194}
195
196static const struct file_operations signalfd_fops = {
197 .release = signalfd_release,
198 .poll = signalfd_poll,
199 .read = signalfd_read,
200};
201
Davide Libenzifba2afa2007-05-10 22:23:13 -0700202asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
203{
204 int error;
205 sigset_t sigmask;
206 struct signalfd_ctx *ctx;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700207 struct file *file;
208 struct inode *inode;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700209
210 if (sizemask != sizeof(sigset_t) ||
211 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
Ulrich Drepperf50cadaa2007-07-26 10:40:55 -0700212 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700213 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
214 signotset(&sigmask);
215
216 if (ufd == -1) {
217 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
218 if (!ctx)
219 return -ENOMEM;
220
Davide Libenzifba2afa2007-05-10 22:23:13 -0700221 ctx->sigmask = sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700222
223 /*
224 * When we call this, the initialization must be complete, since
225 * anon_inode_getfd() will install the fd.
226 */
227 error = anon_inode_getfd(&ufd, &inode, &file, "[signalfd]",
228 &signalfd_fops, ctx);
229 if (error)
230 goto err_fdalloc;
231 } else {
232 file = fget(ufd);
233 if (!file)
234 return -EBADF;
235 ctx = file->private_data;
236 if (file->f_op != &signalfd_fops) {
237 fput(file);
238 return -EINVAL;
239 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700240 spin_lock_irq(&current->sighand->siglock);
241 ctx->sigmask = sigmask;
242 spin_unlock_irq(&current->sighand->siglock);
243
244 wake_up(&current->sighand->signalfd_wqh);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700245 fput(file);
246 }
247
248 return ufd;
249
250err_fdalloc:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700251 kfree(ctx);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700252 return error;
253}
254