507 lines
12 KiB
C
507 lines
12 KiB
C
/******************************************************************************
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* evtchn.c
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*
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* Driver for receiving and demuxing event-channel signals.
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*
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* Copyright (c) 2004-2005, K A Fraser
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* Multi-process extensions Copyright (c) 2004, Steven Smith
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/miscdevice.h>
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#include <linux/major.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/poll.h>
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#include <linux/irq.h>
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#include <linux/init.h>
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#include <linux/gfp.h>
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#include <linux/mutex.h>
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#include <linux/cpu.h>
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#include <xen/events.h>
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#include <xen/evtchn.h>
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#include <asm/xen/hypervisor.h>
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struct per_user_data {
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struct mutex bind_mutex; /* serialize bind/unbind operations */
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/* Notification ring, accessed via /dev/xen/evtchn. */
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#define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t))
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#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
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evtchn_port_t *ring;
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unsigned int ring_cons, ring_prod, ring_overflow;
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struct mutex ring_cons_mutex; /* protect against concurrent readers */
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/* Processes wait on this queue when ring is empty. */
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wait_queue_head_t evtchn_wait;
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struct fasync_struct *evtchn_async_queue;
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const char *name;
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};
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/* Who's bound to each port? */
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static struct per_user_data *port_user[NR_EVENT_CHANNELS];
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static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
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irqreturn_t evtchn_interrupt(int irq, void *data)
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{
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unsigned int port = (unsigned long)data;
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struct per_user_data *u;
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spin_lock(&port_user_lock);
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u = port_user[port];
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disable_irq_nosync(irq);
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if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
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u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port;
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wmb(); /* Ensure ring contents visible */
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if (u->ring_cons == u->ring_prod++) {
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wake_up_interruptible(&u->evtchn_wait);
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kill_fasync(&u->evtchn_async_queue,
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SIGIO, POLL_IN);
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}
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} else {
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u->ring_overflow = 1;
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}
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spin_unlock(&port_user_lock);
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return IRQ_HANDLED;
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}
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static ssize_t evtchn_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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int rc;
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unsigned int c, p, bytes1 = 0, bytes2 = 0;
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struct per_user_data *u = file->private_data;
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/* Whole number of ports. */
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count &= ~(sizeof(evtchn_port_t)-1);
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if (count == 0)
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return 0;
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if (count > PAGE_SIZE)
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count = PAGE_SIZE;
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for (;;) {
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mutex_lock(&u->ring_cons_mutex);
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rc = -EFBIG;
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if (u->ring_overflow)
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goto unlock_out;
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c = u->ring_cons;
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p = u->ring_prod;
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if (c != p)
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break;
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mutex_unlock(&u->ring_cons_mutex);
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if (file->f_flags & O_NONBLOCK)
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return -EAGAIN;
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rc = wait_event_interruptible(u->evtchn_wait,
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u->ring_cons != u->ring_prod);
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if (rc)
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return rc;
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}
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/* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
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if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
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bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
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sizeof(evtchn_port_t);
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bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
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} else {
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bytes1 = (p - c) * sizeof(evtchn_port_t);
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bytes2 = 0;
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}
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/* Truncate chunks according to caller's maximum byte count. */
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if (bytes1 > count) {
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bytes1 = count;
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bytes2 = 0;
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} else if ((bytes1 + bytes2) > count) {
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bytes2 = count - bytes1;
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}
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rc = -EFAULT;
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rmb(); /* Ensure that we see the port before we copy it. */
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if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
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((bytes2 != 0) &&
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copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
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goto unlock_out;
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u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
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rc = bytes1 + bytes2;
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unlock_out:
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mutex_unlock(&u->ring_cons_mutex);
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return rc;
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}
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static ssize_t evtchn_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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int rc, i;
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evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
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struct per_user_data *u = file->private_data;
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if (kbuf == NULL)
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return -ENOMEM;
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/* Whole number of ports. */
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count &= ~(sizeof(evtchn_port_t)-1);
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rc = 0;
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if (count == 0)
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goto out;
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if (count > PAGE_SIZE)
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count = PAGE_SIZE;
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rc = -EFAULT;
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if (copy_from_user(kbuf, buf, count) != 0)
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goto out;
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spin_lock_irq(&port_user_lock);
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for (i = 0; i < (count/sizeof(evtchn_port_t)); i++)
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if ((kbuf[i] < NR_EVENT_CHANNELS) && (port_user[kbuf[i]] == u))
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enable_irq(irq_from_evtchn(kbuf[i]));
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spin_unlock_irq(&port_user_lock);
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rc = count;
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out:
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free_page((unsigned long)kbuf);
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return rc;
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}
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static int evtchn_bind_to_user(struct per_user_data *u, int port)
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{
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int rc = 0;
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/*
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* Ports are never reused, so every caller should pass in a
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* unique port.
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*
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* (Locking not necessary because we haven't registered the
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* interrupt handler yet, and our caller has already
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* serialized bind operations.)
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*/
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BUG_ON(port_user[port] != NULL);
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port_user[port] = u;
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rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
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u->name, (void *)(unsigned long)port);
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if (rc >= 0)
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rc = 0;
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return rc;
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}
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static void evtchn_unbind_from_user(struct per_user_data *u, int port)
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{
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int irq = irq_from_evtchn(port);
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unbind_from_irqhandler(irq, (void *)(unsigned long)port);
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/* make sure we unbind the irq handler before clearing the port */
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barrier();
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port_user[port] = NULL;
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}
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static long evtchn_ioctl(struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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int rc;
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struct per_user_data *u = file->private_data;
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void __user *uarg = (void __user *) arg;
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/* Prevent bind from racing with unbind */
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mutex_lock(&u->bind_mutex);
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switch (cmd) {
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case IOCTL_EVTCHN_BIND_VIRQ: {
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struct ioctl_evtchn_bind_virq bind;
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struct evtchn_bind_virq bind_virq;
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rc = -EFAULT;
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if (copy_from_user(&bind, uarg, sizeof(bind)))
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break;
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bind_virq.virq = bind.virq;
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bind_virq.vcpu = 0;
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rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
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&bind_virq);
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if (rc != 0)
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break;
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rc = evtchn_bind_to_user(u, bind_virq.port);
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if (rc == 0)
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rc = bind_virq.port;
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break;
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}
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case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
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struct ioctl_evtchn_bind_interdomain bind;
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struct evtchn_bind_interdomain bind_interdomain;
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rc = -EFAULT;
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if (copy_from_user(&bind, uarg, sizeof(bind)))
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break;
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bind_interdomain.remote_dom = bind.remote_domain;
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bind_interdomain.remote_port = bind.remote_port;
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rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
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&bind_interdomain);
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if (rc != 0)
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break;
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rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
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if (rc == 0)
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rc = bind_interdomain.local_port;
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break;
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}
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case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
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struct ioctl_evtchn_bind_unbound_port bind;
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struct evtchn_alloc_unbound alloc_unbound;
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rc = -EFAULT;
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if (copy_from_user(&bind, uarg, sizeof(bind)))
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break;
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alloc_unbound.dom = DOMID_SELF;
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alloc_unbound.remote_dom = bind.remote_domain;
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rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
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&alloc_unbound);
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if (rc != 0)
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break;
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rc = evtchn_bind_to_user(u, alloc_unbound.port);
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if (rc == 0)
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rc = alloc_unbound.port;
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break;
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}
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case IOCTL_EVTCHN_UNBIND: {
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struct ioctl_evtchn_unbind unbind;
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rc = -EFAULT;
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if (copy_from_user(&unbind, uarg, sizeof(unbind)))
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break;
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rc = -EINVAL;
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if (unbind.port >= NR_EVENT_CHANNELS)
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break;
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spin_lock_irq(&port_user_lock);
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rc = -ENOTCONN;
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if (port_user[unbind.port] != u) {
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spin_unlock_irq(&port_user_lock);
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break;
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}
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evtchn_unbind_from_user(u, unbind.port);
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spin_unlock_irq(&port_user_lock);
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rc = 0;
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break;
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}
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case IOCTL_EVTCHN_NOTIFY: {
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struct ioctl_evtchn_notify notify;
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rc = -EFAULT;
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if (copy_from_user(¬ify, uarg, sizeof(notify)))
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break;
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if (notify.port >= NR_EVENT_CHANNELS) {
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rc = -EINVAL;
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} else if (port_user[notify.port] != u) {
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rc = -ENOTCONN;
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} else {
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notify_remote_via_evtchn(notify.port);
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rc = 0;
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}
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break;
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}
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case IOCTL_EVTCHN_RESET: {
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/* Initialise the ring to empty. Clear errors. */
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mutex_lock(&u->ring_cons_mutex);
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spin_lock_irq(&port_user_lock);
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u->ring_cons = u->ring_prod = u->ring_overflow = 0;
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spin_unlock_irq(&port_user_lock);
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mutex_unlock(&u->ring_cons_mutex);
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rc = 0;
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break;
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}
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default:
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rc = -ENOSYS;
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break;
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}
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mutex_unlock(&u->bind_mutex);
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return rc;
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}
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static unsigned int evtchn_poll(struct file *file, poll_table *wait)
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{
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unsigned int mask = POLLOUT | POLLWRNORM;
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struct per_user_data *u = file->private_data;
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poll_wait(file, &u->evtchn_wait, wait);
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if (u->ring_cons != u->ring_prod)
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mask |= POLLIN | POLLRDNORM;
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if (u->ring_overflow)
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mask = POLLERR;
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return mask;
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}
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static int evtchn_fasync(int fd, struct file *filp, int on)
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{
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struct per_user_data *u = filp->private_data;
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return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
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}
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static int evtchn_open(struct inode *inode, struct file *filp)
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{
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struct per_user_data *u;
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u = kzalloc(sizeof(*u), GFP_KERNEL);
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if (u == NULL)
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return -ENOMEM;
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u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
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if (u->name == NULL) {
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kfree(u);
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return -ENOMEM;
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}
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init_waitqueue_head(&u->evtchn_wait);
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u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
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if (u->ring == NULL) {
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kfree(u->name);
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kfree(u);
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return -ENOMEM;
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}
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mutex_init(&u->bind_mutex);
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mutex_init(&u->ring_cons_mutex);
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filp->private_data = u;
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return 0;
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}
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static int evtchn_release(struct inode *inode, struct file *filp)
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{
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int i;
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struct per_user_data *u = filp->private_data;
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spin_lock_irq(&port_user_lock);
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free_page((unsigned long)u->ring);
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for (i = 0; i < NR_EVENT_CHANNELS; i++) {
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if (port_user[i] != u)
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continue;
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evtchn_unbind_from_user(port_user[i], i);
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}
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spin_unlock_irq(&port_user_lock);
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kfree(u->name);
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kfree(u);
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return 0;
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}
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static const struct file_operations evtchn_fops = {
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.owner = THIS_MODULE,
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.read = evtchn_read,
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.write = evtchn_write,
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.unlocked_ioctl = evtchn_ioctl,
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.poll = evtchn_poll,
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.fasync = evtchn_fasync,
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.open = evtchn_open,
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.release = evtchn_release,
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};
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static struct miscdevice evtchn_miscdev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "evtchn",
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.fops = &evtchn_fops,
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};
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static int __init evtchn_init(void)
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{
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int err;
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if (!xen_domain())
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return -ENODEV;
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spin_lock_init(&port_user_lock);
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memset(port_user, 0, sizeof(port_user));
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/* Create '/dev/misc/evtchn'. */
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err = misc_register(&evtchn_miscdev);
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if (err != 0) {
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printk(KERN_ALERT "Could not register /dev/misc/evtchn\n");
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return err;
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}
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printk(KERN_INFO "Event-channel device installed.\n");
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return 0;
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}
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static void __exit evtchn_cleanup(void)
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{
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misc_deregister(&evtchn_miscdev);
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}
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module_init(evtchn_init);
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module_exit(evtchn_cleanup);
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MODULE_LICENSE("GPL");
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