vhost-user: add slave-req-fd support
Learn to give a socket to the slave to let him make requests to the master. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marc-André Lureau
Michael S. Tsirkin
parent
2152f3fead
commit
4bbeeba023
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@ -139,6 +139,7 @@ in the ancillary data:
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* VHOST_USER_SET_VRING_KICK
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* VHOST_USER_SET_VRING_CALL
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* VHOST_USER_SET_VRING_ERR
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* VHOST_USER_SET_SLAVE_REQ_FD
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If Master is unable to send the full message or receives a wrong reply it will
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close the connection. An optional reconnection mechanism can be implemented.
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@ -252,6 +253,18 @@ Once the source has finished migration, rings will be stopped by
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the source. No further update must be done before rings are
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restarted.
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Slave communication
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-------------------
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An optional communication channel is provided if the slave declares
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VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make
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requests to the master.
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The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.
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A slave may then send VHOST_USER_SLAVE_* messages to the master
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using this fd communication channel.
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Protocol features
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-----------------
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@ -260,9 +273,10 @@ Protocol features
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#define VHOST_USER_PROTOCOL_F_RARP 2
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#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
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#define VHOST_USER_PROTOCOL_F_MTU 4
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#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
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Message types
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-------------
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Master message types
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--------------------
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* VHOST_USER_GET_FEATURES
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@ -486,6 +500,20 @@ Message types
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If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
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with zero in case the specified MTU is valid, or non-zero otherwise.
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* VHOST_USER_SET_SLAVE_REQ_FD
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Id: 21
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Equivalent ioctl: N/A
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Master payload: N/A
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Set the socket file descriptor for slave initiated requests. It is passed
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in the ancillary data.
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This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
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has been negotiated, and protocol feature bit VHOST_USER_PROTOCOL_F_SLAVE_REQ
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bit is present in VHOST_USER_GET_PROTOCOL_FEATURES.
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If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
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with zero for success, non-zero otherwise.
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VHOST_USER_PROTOCOL_F_REPLY_ACK:
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-------------------------------
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The original vhost-user specification only demands replies for certain
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@ -32,6 +32,7 @@ enum VhostUserProtocolFeature {
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VHOST_USER_PROTOCOL_F_RARP = 2,
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VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
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VHOST_USER_PROTOCOL_F_NET_MTU = 4,
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VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
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VHOST_USER_PROTOCOL_F_MAX
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};
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@ -60,9 +61,15 @@ typedef enum VhostUserRequest {
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VHOST_USER_SET_VRING_ENABLE = 18,
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VHOST_USER_SEND_RARP = 19,
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VHOST_USER_NET_SET_MTU = 20,
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VHOST_USER_SET_SLAVE_REQ_FD = 21,
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VHOST_USER_MAX
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} VhostUserRequest;
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typedef enum VhostUserSlaveRequest {
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VHOST_USER_SLAVE_NONE = 0,
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VHOST_USER_SLAVE_MAX
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} VhostUserSlaveRequest;
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typedef struct VhostUserMemoryRegion {
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uint64_t guest_phys_addr;
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uint64_t memory_size;
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@ -112,6 +119,7 @@ static VhostUserMsg m __attribute__ ((unused));
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struct vhost_user {
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CharBackend *chr;
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int slave_fd;
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};
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static bool ioeventfd_enabled(void)
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@ -578,6 +586,115 @@ static int vhost_user_reset_device(struct vhost_dev *dev)
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return 0;
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}
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static void slave_read(void *opaque)
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{
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struct vhost_dev *dev = opaque;
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struct vhost_user *u = dev->opaque;
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VhostUserMsg msg = { 0, };
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int size, ret = 0;
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/* Read header */
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size = read(u->slave_fd, &msg, VHOST_USER_HDR_SIZE);
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if (size != VHOST_USER_HDR_SIZE) {
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error_report("Failed to read from slave.");
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goto err;
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}
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if (msg.size > VHOST_USER_PAYLOAD_SIZE) {
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error_report("Failed to read msg header."
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" Size %d exceeds the maximum %zu.", msg.size,
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VHOST_USER_PAYLOAD_SIZE);
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goto err;
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}
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/* Read payload */
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size = read(u->slave_fd, &msg.payload, msg.size);
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if (size != msg.size) {
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error_report("Failed to read payload from slave.");
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goto err;
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}
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switch (msg.request) {
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default:
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error_report("Received unexpected msg type.");
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ret = -EINVAL;
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}
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/*
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* REPLY_ACK feature handling. Other reply types has to be managed
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* directly in their request handlers.
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*/
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if (msg.flags & VHOST_USER_NEED_REPLY_MASK) {
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msg.flags &= ~VHOST_USER_NEED_REPLY_MASK;
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msg.flags |= VHOST_USER_REPLY_MASK;
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msg.payload.u64 = !!ret;
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msg.size = sizeof(msg.payload.u64);
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size = write(u->slave_fd, &msg, VHOST_USER_HDR_SIZE + msg.size);
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if (size != VHOST_USER_HDR_SIZE + msg.size) {
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error_report("Failed to send msg reply to slave.");
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goto err;
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}
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}
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return;
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err:
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qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
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close(u->slave_fd);
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u->slave_fd = -1;
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return;
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}
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static int vhost_setup_slave_channel(struct vhost_dev *dev)
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{
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VhostUserMsg msg = {
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.request = VHOST_USER_SET_SLAVE_REQ_FD,
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.flags = VHOST_USER_VERSION,
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};
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struct vhost_user *u = dev->opaque;
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int sv[2], ret = 0;
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bool reply_supported = virtio_has_feature(dev->protocol_features,
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VHOST_USER_PROTOCOL_F_REPLY_ACK);
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if (!virtio_has_feature(dev->protocol_features,
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VHOST_USER_PROTOCOL_F_SLAVE_REQ)) {
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return 0;
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}
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if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
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error_report("socketpair() failed");
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return -1;
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}
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u->slave_fd = sv[0];
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qemu_set_fd_handler(u->slave_fd, slave_read, NULL, dev);
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if (reply_supported) {
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msg.flags |= VHOST_USER_NEED_REPLY_MASK;
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}
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ret = vhost_user_write(dev, &msg, &sv[1], 1);
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if (ret) {
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goto out;
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}
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if (reply_supported) {
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ret = process_message_reply(dev, &msg);
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}
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out:
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close(sv[1]);
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if (ret) {
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qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
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close(u->slave_fd);
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u->slave_fd = -1;
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}
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return ret;
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}
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static int vhost_user_init(struct vhost_dev *dev, void *opaque)
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{
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uint64_t features;
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@ -588,6 +705,7 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
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u = g_new0(struct vhost_user, 1);
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u->chr = opaque;
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u->slave_fd = -1;
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dev->opaque = u;
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err = vhost_user_get_features(dev, &features);
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@ -628,6 +746,11 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
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"VHOST_USER_PROTOCOL_F_LOG_SHMFD feature.");
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}
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err = vhost_setup_slave_channel(dev);
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if (err < 0) {
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return err;
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}
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return 0;
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}
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@ -638,6 +761,10 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
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assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
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u = dev->opaque;
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if (u->slave_fd >= 0) {
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close(u->slave_fd);
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u->slave_fd = -1;
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}
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g_free(u);
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dev->opaque = 0;
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