1 files changed, 342 insertions, 0 deletions

diff --git a/fs/signalfd.c b/fs/signalfd.c
new file mode 100644
index 000000000..7e412ad74
--- /dev/null
+++ b/fs/signalfd.c
@@ -0,0 +1,342 @@
+/*
+ *  fs/signalfd.c
+ *
+ *  Copyright (C) 2003  Linus Torvalds
+ *
+ *  Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
+ *      Changed ->read() to return a siginfo strcture instead of signal number.
+ *      Fixed locking in ->poll().
+ *      Added sighand-detach notification.
+ *      Added fd re-use in sys_signalfd() syscall.
+ *      Now using anonymous inode source.
+ *      Thanks to Oleg Nesterov for useful code review and suggestions.
+ *      More comments and suggestions from Arnd Bergmann.
+ *  Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
+ *      Retrieve multiple signals with one read() call
+ *  Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
+ *      Attach to the sighand only during read() and poll().
+ */
+
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/list.h>
+#include <linux/anon_inodes.h>
+#include <linux/signalfd.h>
+#include <linux/syscalls.h>
+#include <linux/proc_fs.h>
+#include <linux/compat.h>
+
+void signalfd_cleanup(struct sighand_struct *sighand)
+{
+	wait_queue_head_t *wqh = &sighand->signalfd_wqh;
+	/*
+	 * The lockless check can race with remove_wait_queue() in progress,
+	 * but in this case its caller should run under rcu_read_lock() and
+	 * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
+	 */
+	if (likely(!waitqueue_active(wqh)))
+		return;
+
+	/* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
+	wake_up_poll(wqh, POLLHUP | POLLFREE);
+}
+
+struct signalfd_ctx {
+	sigset_t sigmask;
+};
+
+static int signalfd_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static unsigned int signalfd_poll(struct file *file, poll_table *wait)
+{
+	struct signalfd_ctx *ctx = file->private_data;
+	unsigned int events = 0;
+
+	poll_wait(file, &current->sighand->signalfd_wqh, wait);
+
+	spin_lock_irq(&current->sighand->siglock);
+	if (next_signal(&current->pending, &ctx->sigmask) ||
+	    next_signal(&current->signal->shared_pending,
+			&ctx->sigmask))
+		events |= POLLIN;
+	spin_unlock_irq(&current->sighand->siglock);
+
+	return events;
+}
+
+/*
+ * Copied from copy_siginfo_to_user() in kernel/signal.c
+ */
+static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
+			     siginfo_t const *kinfo)
+{
+	long err;
+
+	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
+
+	/*
+	 * Unused members should be zero ...
+	 */
+	err = __clear_user(uinfo, sizeof(*uinfo));
+
+	/*
+	 * If you change siginfo_t structure, please be sure
+	 * this code is fixed accordingly.
+	 */
+	err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
+	err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
+	err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
+	switch (kinfo->si_code & __SI_MASK) {
+	case __SI_KILL:
+		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+		break;
+	case __SI_TIMER:
+		 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
+		 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
+		 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
+		 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
+		break;
+	case __SI_POLL:
+		err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
+		err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
+		break;
+	case __SI_FAULT:
+		err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
+#ifdef __ARCH_SI_TRAPNO
+		err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
+#endif
+#ifdef BUS_MCEERR_AO
+		/* 
+		 * Other callers might not initialize the si_lsb field,
+		 * so check explicitly for the right codes here.
+		 */
+		if (kinfo->si_code == BUS_MCEERR_AR ||
+		    kinfo->si_code == BUS_MCEERR_AO)
+			err |= __put_user((short) kinfo->si_addr_lsb,
+					  &uinfo->ssi_addr_lsb);
+#endif
+		break;
+	case __SI_CHLD:
+		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+		err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
+		err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
+		err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
+		break;
+	case __SI_RT: /* This is not generated by the kernel as of now. */
+	case __SI_MESGQ: /* But this is */
+		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+		err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
+		err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
+		break;
+	default:
+		/*
+		 * This case catches also the signals queued by sigqueue().
+		 */
+		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+		err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
+		err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
+		break;
+	}
+
+	return err ? -EFAULT: sizeof(*uinfo);
+}
+
+static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
+				int nonblock)
+{
+	ssize_t ret;
+	DECLARE_WAITQUEUE(wait, current);
+
+	spin_lock_irq(&current->sighand->siglock);
+	ret = dequeue_signal(current, &ctx->sigmask, info);
+	switch (ret) {
+	case 0:
+		if (!nonblock)
+			break;
+		ret = -EAGAIN;
+	default:
+		spin_unlock_irq(&current->sighand->siglock);
+		return ret;
+	}
+
+	add_wait_queue(&current->sighand->signalfd_wqh, &wait);
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		ret = dequeue_signal(current, &ctx->sigmask, info);
+		if (ret != 0)
+			break;
+		if (signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+		spin_unlock_irq(&current->sighand->siglock);
+		schedule();
+		spin_lock_irq(&current->sighand->siglock);
+	}
+	spin_unlock_irq(&current->sighand->siglock);
+
+	remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
+	__set_current_state(TASK_RUNNING);
+
+	return ret;
+}
+
+/*
+ * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
+ * error code. The "count" parameter must be at least the size of a
+ * "struct signalfd_siginfo".
+ */
+static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
+			     loff_t *ppos)
+{
+	struct signalfd_ctx *ctx = file->private_data;
+	struct signalfd_siginfo __user *siginfo;
+	int nonblock = file->f_flags & O_NONBLOCK;
+	ssize_t ret, total = 0;
+	siginfo_t info;
+
+	count /= sizeof(struct signalfd_siginfo);
+	if (!count)
+		return -EINVAL;
+
+	siginfo = (struct signalfd_siginfo __user *) buf;
+	do {
+		ret = signalfd_dequeue(ctx, &info, nonblock);
+		if (unlikely(ret <= 0))
+			break;
+		ret = signalfd_copyinfo(siginfo, &info);
+		if (ret < 0)
+			break;
+		siginfo++;
+		total += ret;
+		nonblock = 1;
+	} while (--count);
+
+	return total ? total: ret;
+}
+
+#ifdef CONFIG_PROC_FS
+static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct signalfd_ctx *ctx = f->private_data;
+	sigset_t sigmask;
+
+	sigmask = ctx->sigmask;
+	signotset(&sigmask);
+	render_sigset_t(m, "sigmask:\t", &sigmask);
+}
+#endif
+
+static const struct file_operations signalfd_fops = {
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= signalfd_show_fdinfo,
+#endif
+	.release	= signalfd_release,
+	.poll		= signalfd_poll,
+	.read		= signalfd_read,
+	.llseek		= noop_llseek,
+};
+
+SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
+		size_t, sizemask, int, flags)
+{
+	sigset_t sigmask;
+	struct signalfd_ctx *ctx;
+
+	/* Check the SFD_* constants for consistency.  */
+	BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
+	BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
+
+	if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
+		return -EINVAL;
+
+	if (sizemask != sizeof(sigset_t) ||
+	    copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
+		return -EINVAL;
+	sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+	signotset(&sigmask);
+
+	if (ufd == -1) {
+		ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+		if (!ctx)
+			return -ENOMEM;
+
+		ctx->sigmask = sigmask;
+
+		/*
+		 * When we call this, the initialization must be complete, since
+		 * anon_inode_getfd() will install the fd.
+		 */
+		ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
+				       O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
+		if (ufd < 0)
+			kfree(ctx);
+	} else {
+		struct fd f = fdget(ufd);
+		if (!f.file)
+			return -EBADF;
+		ctx = f.file->private_data;
+		if (f.file->f_op != &signalfd_fops) {
+			fdput(f);
+			return -EINVAL;
+		}
+		spin_lock_irq(&current->sighand->siglock);
+		ctx->sigmask = sigmask;
+		spin_unlock_irq(&current->sighand->siglock);
+
+		wake_up(&current->sighand->signalfd_wqh);
+		fdput(f);
+	}
+
+	return ufd;
+}
+
+SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
+		size_t, sizemask)
+{
+	return sys_signalfd4(ufd, user_mask, sizemask, 0);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
+		     const compat_sigset_t __user *,sigmask,
+		     compat_size_t, sigsetsize,
+		     int, flags)
+{
+	compat_sigset_t ss32;
+	sigset_t tmp;
+	sigset_t __user *ksigmask;
+
+	if (sigsetsize != sizeof(compat_sigset_t))
+		return -EINVAL;
+	if (copy_from_user(&ss32, sigmask, sizeof(ss32)))
+		return -EFAULT;
+	sigset_from_compat(&tmp, &ss32);
+	ksigmask = compat_alloc_user_space(sizeof(sigset_t));
+	if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
+		return -EFAULT;
+
+	return sys_signalfd4(ufd, ksigmask, sizeof(sigset_t), flags);
+}
+
+COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
+		     const compat_sigset_t __user *,sigmask,
+		     compat_size_t, sigsetsize)
+{
+	return compat_sys_signalfd4(ufd, sigmask, sigsetsize, 0);
+}
+#endif