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);
91 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
94 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
95 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
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);
104 * Other callers might not initialize the si_lsb field,
105 * so check explicitly for the right codes here.
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);
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);
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);
129 * This case catches also the signals queued by sigqueue().
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);
138 return err ? -EFAULT: sizeof(*uinfo);
141 static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
145 DECLARE_WAITQUEUE(wait, current);
147 spin_lock_irq(¤t->sighand->siglock);
148 ret = dequeue_signal(current, &ctx->sigmask, info);
155 spin_unlock_irq(¤t->sighand->siglock);
159 add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
161 set_current_state(TASK_INTERRUPTIBLE);
162 ret = dequeue_signal(current, &ctx->sigmask, info);
165 if (signal_pending(current)) {
169 spin_unlock_irq(¤t->sighand->siglock);
171 spin_lock_irq(¤t->sighand->siglock);
173 spin_unlock_irq(¤t->sighand->siglock);
175 remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
176 __set_current_state(TASK_RUNNING);
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".
186 static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
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;
195 count /= sizeof(struct signalfd_siginfo);
199 siginfo = (struct signalfd_siginfo __user *) buf;
201 ret = signalfd_dequeue(ctx, &info, nonblock);
202 if (unlikely(ret <= 0))
204 ret = signalfd_copyinfo(siginfo, &info);
212 return total ? total: ret;
215 static const struct file_operations signalfd_fops = {
216 .release = signalfd_release,
217 .poll = signalfd_poll,
218 .read = signalfd_read,
219 .llseek = noop_llseek,
222 SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
223 size_t, sizemask, int, flags)
226 struct signalfd_ctx *ctx;
228 /* Check the SFD_* constants for consistency. */
229 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
230 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
232 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
235 if (sizemask != sizeof(sigset_t) ||
236 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
238 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
242 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
246 ctx->sigmask = sigmask;
249 * When we call this, the initialization must be complete, since
250 * anon_inode_getfd() will install the fd.
252 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
253 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
257 struct file *file = fget(ufd);
260 ctx = file->private_data;
261 if (file->f_op != &signalfd_fops) {
265 spin_lock_irq(¤t->sighand->siglock);
266 ctx->sigmask = sigmask;
267 spin_unlock_irq(¤t->sighand->siglock);
269 wake_up(¤t->sighand->signalfd_wqh);
276 SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
279 return sys_signalfd4(ufd, user_mask, sizemask, 0);