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>
32 #include <linux/proc_fs.h>
33 #include <linux/compat.h>
35 void signalfd_cleanup(struct sighand_struct *sighand)
37 wake_up_pollfree(&sighand->signalfd_wqh);
44 static int signalfd_release(struct inode *inode, struct file *file)
46 kfree(file->private_data);
50 static unsigned int signalfd_poll(struct file *file, poll_table *wait)
52 struct signalfd_ctx *ctx = file->private_data;
53 unsigned int events = 0;
55 poll_wait(file, ¤t->sighand->signalfd_wqh, wait);
57 spin_lock_irq(¤t->sighand->siglock);
58 if (next_signal(¤t->pending, &ctx->sigmask) ||
59 next_signal(¤t->signal->shared_pending,
62 spin_unlock_irq(¤t->sighand->siglock);
68 * Copied from copy_siginfo_to_user() in kernel/signal.c
70 static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
71 siginfo_t const *kinfo)
75 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
78 * Unused members should be zero ...
80 err = __clear_user(uinfo, sizeof(*uinfo));
83 * If you change siginfo_t structure, please be sure
84 * this code is fixed accordingly.
86 err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
87 err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
88 err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
89 switch (kinfo->si_code & __SI_MASK) {
91 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
92 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
95 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
96 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
97 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
98 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
101 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
102 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
105 err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
106 #ifdef __ARCH_SI_TRAPNO
107 err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
111 * Other callers might not initialize the si_lsb field,
112 * so check explicitly for the right codes here.
114 if (kinfo->si_signo == SIGBUS &&
115 (kinfo->si_code == BUS_MCEERR_AR ||
116 kinfo->si_code == BUS_MCEERR_AO))
117 err |= __put_user((short) kinfo->si_addr_lsb,
118 &uinfo->ssi_addr_lsb);
122 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
123 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
124 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
125 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
126 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
128 case __SI_RT: /* This is not generated by the kernel as of now. */
129 case __SI_MESGQ: /* But this is */
130 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
131 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
132 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
133 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
137 * This case catches also the signals queued by sigqueue().
139 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
140 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
141 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
142 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
146 return err ? -EFAULT: sizeof(*uinfo);
149 static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
153 DECLARE_WAITQUEUE(wait, current);
155 spin_lock_irq(¤t->sighand->siglock);
156 ret = dequeue_signal(current, &ctx->sigmask, info);
163 spin_unlock_irq(¤t->sighand->siglock);
167 add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
169 set_current_state(TASK_INTERRUPTIBLE);
170 ret = dequeue_signal(current, &ctx->sigmask, info);
173 if (signal_pending(current)) {
177 spin_unlock_irq(¤t->sighand->siglock);
179 spin_lock_irq(¤t->sighand->siglock);
181 spin_unlock_irq(¤t->sighand->siglock);
183 remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
184 __set_current_state(TASK_RUNNING);
190 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
191 * error code. The "count" parameter must be at least the size of a
192 * "struct signalfd_siginfo".
194 static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
197 struct signalfd_ctx *ctx = file->private_data;
198 struct signalfd_siginfo __user *siginfo;
199 int nonblock = file->f_flags & O_NONBLOCK;
200 ssize_t ret, total = 0;
203 count /= sizeof(struct signalfd_siginfo);
207 siginfo = (struct signalfd_siginfo __user *) buf;
209 ret = signalfd_dequeue(ctx, &info, nonblock);
210 if (unlikely(ret <= 0))
212 ret = signalfd_copyinfo(siginfo, &info);
220 return total ? total: ret;
223 #ifdef CONFIG_PROC_FS
224 static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
226 struct signalfd_ctx *ctx = f->private_data;
229 sigmask = ctx->sigmask;
231 render_sigset_t(m, "sigmask:\t", &sigmask);
235 static const struct file_operations signalfd_fops = {
236 #ifdef CONFIG_PROC_FS
237 .show_fdinfo = signalfd_show_fdinfo,
239 .release = signalfd_release,
240 .poll = signalfd_poll,
241 .read = signalfd_read,
242 .llseek = noop_llseek,
245 SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
246 size_t, sizemask, int, flags)
249 struct signalfd_ctx *ctx;
251 /* Check the SFD_* constants for consistency. */
252 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
253 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
255 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
258 if (sizemask != sizeof(sigset_t) ||
259 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
261 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
265 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
269 ctx->sigmask = sigmask;
272 * When we call this, the initialization must be complete, since
273 * anon_inode_getfd() will install the fd.
275 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
276 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
280 struct fd f = fdget(ufd);
283 ctx = f.file->private_data;
284 if (f.file->f_op != &signalfd_fops) {
288 spin_lock_irq(¤t->sighand->siglock);
289 ctx->sigmask = sigmask;
290 spin_unlock_irq(¤t->sighand->siglock);
292 wake_up(¤t->sighand->signalfd_wqh);
299 SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
302 return sys_signalfd4(ufd, user_mask, sizemask, 0);
306 COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
307 const compat_sigset_t __user *,sigmask,
308 compat_size_t, sigsetsize,
311 compat_sigset_t ss32;
313 sigset_t __user *ksigmask;
315 if (sigsetsize != sizeof(compat_sigset_t))
317 if (copy_from_user(&ss32, sigmask, sizeof(ss32)))
319 sigset_from_compat(&tmp, &ss32);
320 ksigmask = compat_alloc_user_space(sizeof(sigset_t));
321 if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
324 return sys_signalfd4(ufd, ksigmask, sizeof(sigset_t), flags);
327 COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
328 const compat_sigset_t __user *,sigmask,
329 compat_size_t, sigsetsize)
331 return compat_sys_signalfd4(ufd, sigmask, sigsetsize, 0);