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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-28 20:02:17 +00:00
![Michael S. Tsirkin](/assets/img/avatar_default.png)
commit 2ae76693b8bcabf370b981cd00c36cd41d33fabc vhost: replace rcu with mutex replaced rcu sync for memory accesses with VQ mutex locl/unlock. This is correct since all accesses are under VQ mutex, but incomplete: we still do useless rcu lock/unlock operations, someone might copy this code into some other context where this won't be right. This use of RCU is also non standard and hard to understand. Let's copy the pointer to each VQ structure, this way the access rules become straight-forward, and there's no need for RCU anymore. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
338 lines
7.4 KiB
C
338 lines
7.4 KiB
C
/* Copyright (C) 2009 Red Hat, Inc.
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* Author: Michael S. Tsirkin <mst@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2.
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*
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* test virtio server in host kernel.
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*/
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#include <linux/compat.h>
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#include <linux/eventfd.h>
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#include <linux/vhost.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/workqueue.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include "test.h"
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#include "vhost.h"
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/* Max number of bytes transferred before requeueing the job.
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* Using this limit prevents one virtqueue from starving others. */
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#define VHOST_TEST_WEIGHT 0x80000
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enum {
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VHOST_TEST_VQ = 0,
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VHOST_TEST_VQ_MAX = 1,
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};
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struct vhost_test {
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struct vhost_dev dev;
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struct vhost_virtqueue vqs[VHOST_TEST_VQ_MAX];
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};
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/* Expects to be always run from workqueue - which acts as
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* read-size critical section for our kind of RCU. */
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static void handle_vq(struct vhost_test *n)
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{
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struct vhost_virtqueue *vq = &n->vqs[VHOST_TEST_VQ];
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unsigned out, in;
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int head;
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size_t len, total_len = 0;
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void *private;
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mutex_lock(&vq->mutex);
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private = vq->private_data;
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if (!private) {
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mutex_unlock(&vq->mutex);
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return;
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}
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vhost_disable_notify(&n->dev, vq);
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for (;;) {
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head = vhost_get_vq_desc(vq, vq->iov,
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ARRAY_SIZE(vq->iov),
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&out, &in,
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NULL, NULL);
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/* On error, stop handling until the next kick. */
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if (unlikely(head < 0))
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break;
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/* Nothing new? Wait for eventfd to tell us they refilled. */
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if (head == vq->num) {
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if (unlikely(vhost_enable_notify(&n->dev, vq))) {
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vhost_disable_notify(&n->dev, vq);
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continue;
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}
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break;
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}
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if (in) {
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vq_err(vq, "Unexpected descriptor format for TX: "
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"out %d, int %d\n", out, in);
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break;
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}
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len = iov_length(vq->iov, out);
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/* Sanity check */
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if (!len) {
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vq_err(vq, "Unexpected 0 len for TX\n");
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break;
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}
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vhost_add_used_and_signal(&n->dev, vq, head, 0);
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total_len += len;
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if (unlikely(total_len >= VHOST_TEST_WEIGHT)) {
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vhost_poll_queue(&vq->poll);
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break;
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}
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}
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mutex_unlock(&vq->mutex);
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}
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static void handle_vq_kick(struct vhost_work *work)
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{
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struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
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poll.work);
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struct vhost_test *n = container_of(vq->dev, struct vhost_test, dev);
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handle_vq(n);
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}
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static int vhost_test_open(struct inode *inode, struct file *f)
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{
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struct vhost_test *n = kmalloc(sizeof *n, GFP_KERNEL);
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struct vhost_dev *dev;
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struct vhost_virtqueue **vqs;
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if (!n)
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return -ENOMEM;
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vqs = kmalloc(VHOST_TEST_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
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if (!vqs) {
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kfree(n);
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return -ENOMEM;
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}
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dev = &n->dev;
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vqs[VHOST_TEST_VQ] = &n->vqs[VHOST_TEST_VQ];
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n->vqs[VHOST_TEST_VQ].handle_kick = handle_vq_kick;
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vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX);
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f->private_data = n;
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return 0;
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}
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static void *vhost_test_stop_vq(struct vhost_test *n,
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struct vhost_virtqueue *vq)
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{
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void *private;
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mutex_lock(&vq->mutex);
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private = vq->private_data;
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vq->private_data = NULL;
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mutex_unlock(&vq->mutex);
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return private;
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}
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static void vhost_test_stop(struct vhost_test *n, void **privatep)
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{
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*privatep = vhost_test_stop_vq(n, n->vqs + VHOST_TEST_VQ);
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}
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static void vhost_test_flush_vq(struct vhost_test *n, int index)
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{
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vhost_poll_flush(&n->vqs[index].poll);
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}
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static void vhost_test_flush(struct vhost_test *n)
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{
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vhost_test_flush_vq(n, VHOST_TEST_VQ);
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}
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static int vhost_test_release(struct inode *inode, struct file *f)
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{
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struct vhost_test *n = f->private_data;
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void *private;
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vhost_test_stop(n, &private);
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vhost_test_flush(n);
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vhost_dev_cleanup(&n->dev, false);
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/* We do an extra flush before freeing memory,
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* since jobs can re-queue themselves. */
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vhost_test_flush(n);
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kfree(n);
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return 0;
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}
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static long vhost_test_run(struct vhost_test *n, int test)
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{
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void *priv, *oldpriv;
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struct vhost_virtqueue *vq;
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int r, index;
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if (test < 0 || test > 1)
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return -EINVAL;
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mutex_lock(&n->dev.mutex);
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r = vhost_dev_check_owner(&n->dev);
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if (r)
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goto err;
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for (index = 0; index < n->dev.nvqs; ++index) {
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/* Verify that ring has been setup correctly. */
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if (!vhost_vq_access_ok(&n->vqs[index])) {
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r = -EFAULT;
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goto err;
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}
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}
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for (index = 0; index < n->dev.nvqs; ++index) {
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vq = n->vqs + index;
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mutex_lock(&vq->mutex);
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priv = test ? n : NULL;
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/* start polling new socket */
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oldpriv = vq->private_data;
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vq->private_data = priv;
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r = vhost_init_used(&n->vqs[index]);
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mutex_unlock(&vq->mutex);
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if (r)
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goto err;
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if (oldpriv) {
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vhost_test_flush_vq(n, index);
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}
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}
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mutex_unlock(&n->dev.mutex);
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return 0;
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err:
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mutex_unlock(&n->dev.mutex);
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return r;
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}
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static long vhost_test_reset_owner(struct vhost_test *n)
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{
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void *priv = NULL;
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long err;
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struct vhost_memory *memory;
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mutex_lock(&n->dev.mutex);
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err = vhost_dev_check_owner(&n->dev);
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if (err)
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goto done;
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memory = vhost_dev_reset_owner_prepare();
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if (!memory) {
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err = -ENOMEM;
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goto done;
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}
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vhost_test_stop(n, &priv);
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vhost_test_flush(n);
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vhost_dev_reset_owner(&n->dev, memory);
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done:
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mutex_unlock(&n->dev.mutex);
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return err;
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}
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static int vhost_test_set_features(struct vhost_test *n, u64 features)
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{
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struct vhost_virtqueue *vq;
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mutex_lock(&n->dev.mutex);
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if ((features & (1 << VHOST_F_LOG_ALL)) &&
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!vhost_log_access_ok(&n->dev)) {
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mutex_unlock(&n->dev.mutex);
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return -EFAULT;
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}
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vq = &n->vqs[VHOST_TEST_VQ];
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mutex_lock(&vq->mutex);
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vq->acked_features = features;
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mutex_unlock(&vq->mutex);
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mutex_unlock(&n->dev.mutex);
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return 0;
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}
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static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
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unsigned long arg)
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{
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struct vhost_test *n = f->private_data;
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void __user *argp = (void __user *)arg;
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u64 __user *featurep = argp;
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int test;
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u64 features;
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int r;
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switch (ioctl) {
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case VHOST_TEST_RUN:
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if (copy_from_user(&test, argp, sizeof test))
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return -EFAULT;
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return vhost_test_run(n, test);
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case VHOST_GET_FEATURES:
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features = VHOST_FEATURES;
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if (copy_to_user(featurep, &features, sizeof features))
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return -EFAULT;
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return 0;
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case VHOST_SET_FEATURES:
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if (copy_from_user(&features, featurep, sizeof features))
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return -EFAULT;
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if (features & ~VHOST_FEATURES)
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return -EOPNOTSUPP;
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return vhost_test_set_features(n, features);
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case VHOST_RESET_OWNER:
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return vhost_test_reset_owner(n);
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default:
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mutex_lock(&n->dev.mutex);
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r = vhost_dev_ioctl(&n->dev, ioctl, argp);
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if (r == -ENOIOCTLCMD)
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r = vhost_vring_ioctl(&n->dev, ioctl, argp);
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vhost_test_flush(n);
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mutex_unlock(&n->dev.mutex);
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return r;
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}
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}
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#ifdef CONFIG_COMPAT
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static long vhost_test_compat_ioctl(struct file *f, unsigned int ioctl,
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unsigned long arg)
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{
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return vhost_test_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
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}
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#endif
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static const struct file_operations vhost_test_fops = {
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.owner = THIS_MODULE,
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.release = vhost_test_release,
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.unlocked_ioctl = vhost_test_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = vhost_test_compat_ioctl,
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#endif
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.open = vhost_test_open,
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.llseek = noop_llseek,
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};
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static struct miscdevice vhost_test_misc = {
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MISC_DYNAMIC_MINOR,
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"vhost-test",
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&vhost_test_fops,
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};
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static int vhost_test_init(void)
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{
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return misc_register(&vhost_test_misc);
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}
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module_init(vhost_test_init);
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static void vhost_test_exit(void)
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{
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misc_deregister(&vhost_test_misc);
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}
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module_exit(vhost_test_exit);
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MODULE_VERSION("0.0.1");
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Michael S. Tsirkin");
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MODULE_DESCRIPTION("Host kernel side for virtio simulator");
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