--- /dev/null
+/*
+ * 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, ¤t->sighand->signalfd_wqh, wait);
+
+ spin_lock_irq(¤t->sighand->siglock);
+ if (next_signal(¤t->pending, &ctx->sigmask) ||
+ next_signal(¤t->signal->shared_pending,
+ &ctx->sigmask))
+ events |= POLLIN;
+ spin_unlock_irq(¤t->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(¤t->sighand->siglock);
+ ret = dequeue_signal(current, &ctx->sigmask, info);
+ switch (ret) {
+ case 0:
+ if (!nonblock)
+ break;
+ ret = -EAGAIN;
+ default:
+ spin_unlock_irq(¤t->sighand->siglock);
+ return ret;
+ }
+
+ add_wait_queue(¤t->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(¤t->sighand->siglock);
+ schedule();
+ spin_lock_irq(¤t->sighand->siglock);
+ }
+ spin_unlock_irq(¤t->sighand->siglock);
+
+ remove_wait_queue(¤t->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(¤t->sighand->siglock);
+ ctx->sigmask = sigmask;
+ spin_unlock_irq(¤t->sighand->siglock);
+
+ wake_up(¤t->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
Code Review / kvmfornfv.git / blobdiff