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>
33 void signalfd_cleanup(struct sighand_struct *sighand)
35 wait_queue_head_t *wqh = &sighand->signalfd_wqh;
37 if (likely(!waitqueue_active(wqh)))
40 /* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
41 wake_up_poll(wqh, POLLHUP | POLLFREE);
48 static int signalfd_release(struct inode *inode, struct file *file)
50 kfree(file->private_data);
54 static unsigned int signalfd_poll(struct file *file, poll_table *wait)
56 struct signalfd_ctx *ctx = file->private_data;
57 unsigned int events = 0;
59 poll_wait(file, ¤t->sighand->signalfd_wqh, wait);
61 spin_lock_irq(¤t->sighand->siglock);
62 if (next_signal(¤t->pending, &ctx->sigmask) ||
63 next_signal(¤t->signal->shared_pending,
66 spin_unlock_irq(¤t->sighand->siglock);
72 * Copied from copy_siginfo_to_user() in kernel/signal.c
74 static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
75 siginfo_t const *kinfo)
79 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
82 * Unused members should be zero ...
84 err = __clear_user(uinfo, sizeof(*uinfo));
87 * If you change siginfo_t structure, please be sure
88 * this code is fixed accordingly.
90 err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
91 err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
92 err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
93 switch (kinfo->si_code & __SI_MASK) {
95 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
96 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
99 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
100 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
101 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
102 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
105 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
106 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
109 err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
110 #ifdef __ARCH_SI_TRAPNO
111 err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
115 * Other callers might not initialize the si_lsb field,
116 * so check explicitly for the right codes here.
118 if (kinfo->si_code == BUS_MCEERR_AR ||
119 kinfo->si_code == BUS_MCEERR_AO)
120 err |= __put_user((short) kinfo->si_addr_lsb,
121 &uinfo->ssi_addr_lsb);
125 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
126 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
127 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
128 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
129 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
131 case __SI_RT: /* This is not generated by the kernel as of now. */
132 case __SI_MESGQ: /* But this is */
133 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
134 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
135 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
136 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
140 * This case catches also the signals queued by sigqueue().
142 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
143 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
144 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
145 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
149 return err ? -EFAULT: sizeof(*uinfo);
152 static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
156 DECLARE_WAITQUEUE(wait, current);
158 spin_lock_irq(¤t->sighand->siglock);
159 ret = dequeue_signal(current, &ctx->sigmask, info);
166 spin_unlock_irq(¤t->sighand->siglock);
170 add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
172 set_current_state(TASK_INTERRUPTIBLE);
173 ret = dequeue_signal(current, &ctx->sigmask, info);
176 if (signal_pending(current)) {
180 spin_unlock_irq(¤t->sighand->siglock);
182 spin_lock_irq(¤t->sighand->siglock);
184 spin_unlock_irq(¤t->sighand->siglock);
186 remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
187 __set_current_state(TASK_RUNNING);
193 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
194 * error code. The "count" parameter must be at least the size of a
195 * "struct signalfd_siginfo".
197 static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
200 struct signalfd_ctx *ctx = file->private_data;
201 struct signalfd_siginfo __user *siginfo;
202 int nonblock = file->f_flags & O_NONBLOCK;
203 ssize_t ret, total = 0;
206 count /= sizeof(struct signalfd_siginfo);
210 siginfo = (struct signalfd_siginfo __user *) buf;
212 ret = signalfd_dequeue(ctx, &info, nonblock);
213 if (unlikely(ret <= 0))
215 ret = signalfd_copyinfo(siginfo, &info);
223 return total ? total: ret;
226 static const struct file_operations signalfd_fops = {
227 .release = signalfd_release,
228 .poll = signalfd_poll,
229 .read = signalfd_read,
230 .llseek = noop_llseek,
233 SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
234 size_t, sizemask, int, flags)
237 struct signalfd_ctx *ctx;
239 /* Check the SFD_* constants for consistency. */
240 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
241 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
243 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
246 if (sizemask != sizeof(sigset_t) ||
247 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
249 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
253 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
257 ctx->sigmask = sigmask;
260 * When we call this, the initialization must be complete, since
261 * anon_inode_getfd() will install the fd.
263 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
264 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
268 struct file *file = fget(ufd);
271 ctx = file->private_data;
272 if (file->f_op != &signalfd_fops) {
276 spin_lock_irq(¤t->sighand->siglock);
277 ctx->sigmask = sigmask;
278 spin_unlock_irq(¤t->sighand->siglock);
280 wake_up(¤t->sighand->signalfd_wqh);
287 SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
290 return sys_signalfd4(ufd, user_mask, sizemask, 0);