4 * Copyright (C) 2003 Linus Torvalds
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().
20 #include <linux/file.h>
21 #include <linux/poll.h>
22 #include <linux/init.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>
37 static int signalfd_release(struct inode *inode, struct file *file)
39 kfree(file->private_data);
43 static unsigned int signalfd_poll(struct file *file, poll_table *wait)
45 struct signalfd_ctx *ctx = file->private_data;
46 unsigned int events = 0;
48 poll_wait(file, ¤t->sighand->signalfd_wqh, wait);
50 spin_lock_irq(¤t->sighand->siglock);
51 if (next_signal(¤t->pending, &ctx->sigmask) ||
52 next_signal(¤t->signal->shared_pending,
55 spin_unlock_irq(¤t->sighand->siglock);
61 * Copied from copy_siginfo_to_user() in kernel/signal.c
63 static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
64 siginfo_t const *kinfo)
68 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
71 * Unused members should be zero ...
73 err = __clear_user(uinfo, sizeof(*uinfo));
76 * If you change siginfo_t structure, please be sure
77 * this code is fixed accordingly.
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) {
84 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
85 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
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);
93 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
94 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
97 err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
98 #ifdef __ARCH_SI_TRAPNO
99 err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
103 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
104 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
105 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
106 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
107 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
109 case __SI_RT: /* This is not generated by the kernel as of now. */
110 case __SI_MESGQ: /* But this is */
111 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
112 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
113 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
117 * This case catches also the signals queued by sigqueue().
119 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
120 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
121 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
122 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
126 return err ? -EFAULT: sizeof(*uinfo);
129 static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
133 DECLARE_WAITQUEUE(wait, current);
135 spin_lock_irq(¤t->sighand->siglock);
136 ret = dequeue_signal(current, &ctx->sigmask, info);
143 spin_unlock_irq(¤t->sighand->siglock);
147 add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
149 set_current_state(TASK_INTERRUPTIBLE);
150 ret = dequeue_signal(current, &ctx->sigmask, info);
153 if (signal_pending(current)) {
157 spin_unlock_irq(¤t->sighand->siglock);
159 spin_lock_irq(¤t->sighand->siglock);
161 spin_unlock_irq(¤t->sighand->siglock);
163 remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
164 __set_current_state(TASK_RUNNING);
170 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
171 * error code. The "count" parameter must be at least the size of a
172 * "struct signalfd_siginfo".
174 static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
177 struct signalfd_ctx *ctx = file->private_data;
178 struct signalfd_siginfo __user *siginfo;
179 int nonblock = file->f_flags & O_NONBLOCK;
180 ssize_t ret, total = 0;
183 count /= sizeof(struct signalfd_siginfo);
187 siginfo = (struct signalfd_siginfo __user *) buf;
189 ret = signalfd_dequeue(ctx, &info, nonblock);
190 if (unlikely(ret <= 0))
192 ret = signalfd_copyinfo(siginfo, &info);
200 return total ? total: ret;
203 static const struct file_operations signalfd_fops = {
204 .release = signalfd_release,
205 .poll = signalfd_poll,
206 .read = signalfd_read,
209 SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
210 size_t, sizemask, int, flags)
213 struct signalfd_ctx *ctx;
215 /* Check the SFD_* constants for consistency. */
216 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
217 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
219 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
222 if (sizemask != sizeof(sigset_t) ||
223 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
225 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
229 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
233 ctx->sigmask = sigmask;
236 * When we call this, the initialization must be complete, since
237 * anon_inode_getfd() will install the fd.
239 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
240 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
244 struct file *file = fget(ufd);
247 ctx = file->private_data;
248 if (file->f_op != &signalfd_fops) {
252 spin_lock_irq(¤t->sighand->siglock);
253 ctx->sigmask = sigmask;
254 spin_unlock_irq(¤t->sighand->siglock);
256 wake_up(¤t->sighand->signalfd_wqh);
263 SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
266 return sys_signalfd4(ufd, user_mask, sizemask, 0);