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![Gustavo A. R. Silva](/assets/img/avatar_default.png)
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
364 lines
9 KiB
C
364 lines
9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/signalfd.c
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*
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* Copyright (C) 2003 Linus Torvalds
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*
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* Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
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* Changed ->read() to return a siginfo strcture instead of signal number.
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* Fixed locking in ->poll().
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* Added sighand-detach notification.
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* Added fd re-use in sys_signalfd() syscall.
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* Now using anonymous inode source.
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* Thanks to Oleg Nesterov for useful code review and suggestions.
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* More comments and suggestions from Arnd Bergmann.
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* Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
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* Retrieve multiple signals with one read() call
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* Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
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* Attach to the sighand only during read() and poll().
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*/
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#include <linux/file.h>
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#include <linux/poll.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/list.h>
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#include <linux/anon_inodes.h>
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#include <linux/signalfd.h>
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#include <linux/syscalls.h>
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#include <linux/proc_fs.h>
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#include <linux/compat.h>
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void signalfd_cleanup(struct sighand_struct *sighand)
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{
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wait_queue_head_t *wqh = &sighand->signalfd_wqh;
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/*
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* The lockless check can race with remove_wait_queue() in progress,
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* but in this case its caller should run under rcu_read_lock() and
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* sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
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*/
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if (likely(!waitqueue_active(wqh)))
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return;
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/* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */
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wake_up_poll(wqh, EPOLLHUP | POLLFREE);
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}
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struct signalfd_ctx {
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sigset_t sigmask;
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};
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static int signalfd_release(struct inode *inode, struct file *file)
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{
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kfree(file->private_data);
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return 0;
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}
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static __poll_t signalfd_poll(struct file *file, poll_table *wait)
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{
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struct signalfd_ctx *ctx = file->private_data;
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__poll_t events = 0;
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poll_wait(file, ¤t->sighand->signalfd_wqh, wait);
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spin_lock_irq(¤t->sighand->siglock);
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if (next_signal(¤t->pending, &ctx->sigmask) ||
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next_signal(¤t->signal->shared_pending,
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&ctx->sigmask))
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events |= EPOLLIN;
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spin_unlock_irq(¤t->sighand->siglock);
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return events;
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}
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/*
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* Copied from copy_siginfo_to_user() in kernel/signal.c
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*/
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static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
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kernel_siginfo_t const *kinfo)
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{
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struct signalfd_siginfo new;
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BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
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/*
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* Unused members should be zero ...
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*/
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memset(&new, 0, sizeof(new));
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/*
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* If you change siginfo_t structure, please be sure
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* this code is fixed accordingly.
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*/
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new.ssi_signo = kinfo->si_signo;
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new.ssi_errno = kinfo->si_errno;
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new.ssi_code = kinfo->si_code;
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switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
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case SIL_KILL:
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new.ssi_pid = kinfo->si_pid;
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new.ssi_uid = kinfo->si_uid;
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break;
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case SIL_TIMER:
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new.ssi_tid = kinfo->si_tid;
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new.ssi_overrun = kinfo->si_overrun;
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new.ssi_ptr = (long) kinfo->si_ptr;
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new.ssi_int = kinfo->si_int;
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break;
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case SIL_POLL:
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new.ssi_band = kinfo->si_band;
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new.ssi_fd = kinfo->si_fd;
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break;
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case SIL_FAULT_BNDERR:
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case SIL_FAULT_PKUERR:
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/*
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* Fall through to the SIL_FAULT case. Both SIL_FAULT_BNDERR
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* and SIL_FAULT_PKUERR are only generated by faults that
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* deliver them synchronously to userspace. In case someone
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* injects one of these signals and signalfd catches it treat
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* it as SIL_FAULT.
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*/
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case SIL_FAULT:
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new.ssi_addr = (long) kinfo->si_addr;
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#ifdef __ARCH_SI_TRAPNO
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new.ssi_trapno = kinfo->si_trapno;
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#endif
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break;
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case SIL_FAULT_MCEERR:
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new.ssi_addr = (long) kinfo->si_addr;
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#ifdef __ARCH_SI_TRAPNO
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new.ssi_trapno = kinfo->si_trapno;
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#endif
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new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
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break;
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case SIL_CHLD:
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new.ssi_pid = kinfo->si_pid;
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new.ssi_uid = kinfo->si_uid;
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new.ssi_status = kinfo->si_status;
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new.ssi_utime = kinfo->si_utime;
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new.ssi_stime = kinfo->si_stime;
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break;
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case SIL_RT:
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/*
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* This case catches also the signals queued by sigqueue().
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*/
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new.ssi_pid = kinfo->si_pid;
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new.ssi_uid = kinfo->si_uid;
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new.ssi_ptr = (long) kinfo->si_ptr;
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new.ssi_int = kinfo->si_int;
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break;
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case SIL_SYS:
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new.ssi_call_addr = (long) kinfo->si_call_addr;
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new.ssi_syscall = kinfo->si_syscall;
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new.ssi_arch = kinfo->si_arch;
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break;
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}
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if (copy_to_user(uinfo, &new, sizeof(struct signalfd_siginfo)))
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return -EFAULT;
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return sizeof(*uinfo);
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}
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static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info,
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int nonblock)
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{
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ssize_t ret;
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DECLARE_WAITQUEUE(wait, current);
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spin_lock_irq(¤t->sighand->siglock);
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ret = dequeue_signal(current, &ctx->sigmask, info);
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switch (ret) {
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case 0:
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if (!nonblock)
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break;
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ret = -EAGAIN;
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fallthrough;
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default:
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spin_unlock_irq(¤t->sighand->siglock);
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return ret;
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}
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add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
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for (;;) {
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set_current_state(TASK_INTERRUPTIBLE);
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ret = dequeue_signal(current, &ctx->sigmask, info);
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if (ret != 0)
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break;
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if (signal_pending(current)) {
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ret = -ERESTARTSYS;
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break;
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}
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spin_unlock_irq(¤t->sighand->siglock);
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schedule();
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spin_lock_irq(¤t->sighand->siglock);
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}
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spin_unlock_irq(¤t->sighand->siglock);
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remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
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__set_current_state(TASK_RUNNING);
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return ret;
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}
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/*
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* Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
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* error code. The "count" parameter must be at least the size of a
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* "struct signalfd_siginfo".
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*/
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static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
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loff_t *ppos)
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{
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struct signalfd_ctx *ctx = file->private_data;
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struct signalfd_siginfo __user *siginfo;
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int nonblock = file->f_flags & O_NONBLOCK;
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ssize_t ret, total = 0;
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kernel_siginfo_t info;
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count /= sizeof(struct signalfd_siginfo);
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if (!count)
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return -EINVAL;
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siginfo = (struct signalfd_siginfo __user *) buf;
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do {
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ret = signalfd_dequeue(ctx, &info, nonblock);
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if (unlikely(ret <= 0))
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break;
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ret = signalfd_copyinfo(siginfo, &info);
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if (ret < 0)
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break;
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siginfo++;
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total += ret;
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nonblock = 1;
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} while (--count);
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return total ? total: ret;
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}
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#ifdef CONFIG_PROC_FS
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static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
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{
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struct signalfd_ctx *ctx = f->private_data;
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sigset_t sigmask;
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sigmask = ctx->sigmask;
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signotset(&sigmask);
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render_sigset_t(m, "sigmask:\t", &sigmask);
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}
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#endif
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static const struct file_operations signalfd_fops = {
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#ifdef CONFIG_PROC_FS
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.show_fdinfo = signalfd_show_fdinfo,
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#endif
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.release = signalfd_release,
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.poll = signalfd_poll,
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.read = signalfd_read,
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.llseek = noop_llseek,
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};
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static int do_signalfd4(int ufd, sigset_t *mask, int flags)
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{
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struct signalfd_ctx *ctx;
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/* Check the SFD_* constants for consistency. */
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BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
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BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
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if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
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return -EINVAL;
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sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
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signotset(mask);
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if (ufd == -1) {
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ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->sigmask = *mask;
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/*
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* When we call this, the initialization must be complete, since
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* anon_inode_getfd() will install the fd.
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*/
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ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
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O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
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if (ufd < 0)
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kfree(ctx);
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} else {
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struct fd f = fdget(ufd);
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if (!f.file)
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return -EBADF;
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ctx = f.file->private_data;
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if (f.file->f_op != &signalfd_fops) {
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fdput(f);
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return -EINVAL;
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}
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spin_lock_irq(¤t->sighand->siglock);
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ctx->sigmask = *mask;
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spin_unlock_irq(¤t->sighand->siglock);
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wake_up(¤t->sighand->signalfd_wqh);
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fdput(f);
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}
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return ufd;
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}
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SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
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size_t, sizemask, int, flags)
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{
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sigset_t mask;
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if (sizemask != sizeof(sigset_t))
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return -EINVAL;
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if (copy_from_user(&mask, user_mask, sizeof(mask)))
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return -EFAULT;
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return do_signalfd4(ufd, &mask, flags);
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}
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SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
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size_t, sizemask)
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{
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sigset_t mask;
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if (sizemask != sizeof(sigset_t))
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return -EINVAL;
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if (copy_from_user(&mask, user_mask, sizeof(mask)))
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return -EFAULT;
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return do_signalfd4(ufd, &mask, 0);
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}
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#ifdef CONFIG_COMPAT
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static long do_compat_signalfd4(int ufd,
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const compat_sigset_t __user *user_mask,
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compat_size_t sigsetsize, int flags)
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{
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sigset_t mask;
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if (sigsetsize != sizeof(compat_sigset_t))
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return -EINVAL;
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if (get_compat_sigset(&mask, user_mask))
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return -EFAULT;
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return do_signalfd4(ufd, &mask, flags);
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}
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COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
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const compat_sigset_t __user *, user_mask,
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compat_size_t, sigsetsize,
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int, flags)
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{
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return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);
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}
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COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
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const compat_sigset_t __user *, user_mask,
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compat_size_t, sigsetsize)
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{
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return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);
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}
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#endif
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