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455 lines
12 KiB
455 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* An implementation of host initiated guest snapshot. |
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* |
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* Copyright (C) 2013, Microsoft, Inc. |
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* Author : K. Y. Srinivasan <[email protected]> |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/net.h> |
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#include <linux/nls.h> |
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#include <linux/connector.h> |
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#include <linux/workqueue.h> |
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#include <linux/hyperv.h> |
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#include <asm/hyperv-tlfs.h> |
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#include "hyperv_vmbus.h" |
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#include "hv_utils_transport.h" |
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#define VSS_MAJOR 5 |
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#define VSS_MINOR 0 |
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#define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR) |
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#define VSS_VER_COUNT 1 |
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static const int vss_versions[] = { |
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VSS_VERSION |
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}; |
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#define FW_VER_COUNT 1 |
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static const int fw_versions[] = { |
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UTIL_FW_VERSION |
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}; |
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/* |
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* Timeout values are based on expecations from host |
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*/ |
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#define VSS_FREEZE_TIMEOUT (15 * 60) |
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/* |
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* Global state maintained for transaction that is being processed. For a class |
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* of integration services, including the "VSS service", the specified protocol |
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* is a "request/response" protocol which means that there can only be single |
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* outstanding transaction from the host at any given point in time. We use |
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* this to simplify memory management in this driver - we cache and process |
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* only one message at a time. |
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* |
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* While the request/response protocol is guaranteed by the host, we further |
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* ensure this by serializing packet processing in this driver - we do not |
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* read additional packets from the VMBUs until the current packet is fully |
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* handled. |
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*/ |
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static struct { |
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int state; /* hvutil_device_state */ |
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int recv_len; /* number of bytes received. */ |
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struct vmbus_channel *recv_channel; /* chn we got the request */ |
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u64 recv_req_id; /* request ID. */ |
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struct hv_vss_msg *msg; /* current message */ |
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} vss_transaction; |
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static void vss_respond_to_host(int error); |
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/* |
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* This state maintains the version number registered by the daemon. |
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*/ |
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static int dm_reg_value; |
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static const char vss_devname[] = "vmbus/hv_vss"; |
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static __u8 *recv_buffer; |
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static struct hvutil_transport *hvt; |
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static void vss_timeout_func(struct work_struct *dummy); |
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static void vss_handle_request(struct work_struct *dummy); |
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static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); |
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static DECLARE_WORK(vss_handle_request_work, vss_handle_request); |
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static void vss_poll_wrapper(void *channel) |
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{ |
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/* Transaction is finished, reset the state here to avoid races. */ |
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vss_transaction.state = HVUTIL_READY; |
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tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event); |
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} |
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/* |
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* Callback when data is received from user mode. |
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*/ |
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static void vss_timeout_func(struct work_struct *dummy) |
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{ |
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/* |
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* Timeout waiting for userspace component to reply happened. |
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*/ |
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pr_warn("VSS: timeout waiting for daemon to reply\n"); |
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vss_respond_to_host(HV_E_FAIL); |
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hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); |
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} |
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static void vss_register_done(void) |
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{ |
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hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); |
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pr_debug("VSS: userspace daemon registered\n"); |
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} |
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static int vss_handle_handshake(struct hv_vss_msg *vss_msg) |
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{ |
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u32 our_ver = VSS_OP_REGISTER1; |
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switch (vss_msg->vss_hdr.operation) { |
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case VSS_OP_REGISTER: |
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/* Daemon doesn't expect us to reply */ |
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dm_reg_value = VSS_OP_REGISTER; |
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break; |
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case VSS_OP_REGISTER1: |
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/* Daemon expects us to reply with our own version */ |
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if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver), |
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vss_register_done)) |
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return -EFAULT; |
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dm_reg_value = VSS_OP_REGISTER1; |
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break; |
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default: |
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return -EINVAL; |
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} |
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pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value); |
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return 0; |
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} |
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static int vss_on_msg(void *msg, int len) |
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{ |
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struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg; |
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if (len != sizeof(*vss_msg)) { |
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pr_debug("VSS: Message size does not match length\n"); |
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return -EINVAL; |
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} |
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if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER || |
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vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) { |
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/* |
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* Don't process registration messages if we're in the middle |
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* of a transaction processing. |
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*/ |
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if (vss_transaction.state > HVUTIL_READY) { |
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pr_debug("VSS: Got unexpected registration request\n"); |
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return -EINVAL; |
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} |
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return vss_handle_handshake(vss_msg); |
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} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { |
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vss_transaction.state = HVUTIL_USERSPACE_RECV; |
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if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP) |
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vss_transaction.msg->vss_cf.flags = |
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VSS_HBU_NO_AUTO_RECOVERY; |
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if (cancel_delayed_work_sync(&vss_timeout_work)) { |
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vss_respond_to_host(vss_msg->error); |
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/* Transaction is finished, reset the state. */ |
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hv_poll_channel(vss_transaction.recv_channel, |
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vss_poll_wrapper); |
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} |
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} else { |
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/* This is a spurious call! */ |
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pr_debug("VSS: Transaction not active\n"); |
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return -EINVAL; |
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} |
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return 0; |
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} |
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static void vss_send_op(void) |
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{ |
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int op = vss_transaction.msg->vss_hdr.operation; |
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int rc; |
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struct hv_vss_msg *vss_msg; |
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/* The transaction state is wrong. */ |
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if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) { |
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pr_debug("VSS: Unexpected attempt to send to daemon\n"); |
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return; |
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} |
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vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); |
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if (!vss_msg) |
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return; |
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vss_msg->vss_hdr.operation = op; |
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vss_transaction.state = HVUTIL_USERSPACE_REQ; |
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schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ? |
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VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ); |
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rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); |
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if (rc) { |
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pr_warn("VSS: failed to communicate to the daemon: %d\n", rc); |
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if (cancel_delayed_work_sync(&vss_timeout_work)) { |
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vss_respond_to_host(HV_E_FAIL); |
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vss_transaction.state = HVUTIL_READY; |
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} |
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} |
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kfree(vss_msg); |
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} |
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static void vss_handle_request(struct work_struct *dummy) |
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{ |
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switch (vss_transaction.msg->vss_hdr.operation) { |
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/* |
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* Initiate a "freeze/thaw" operation in the guest. |
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* We respond to the host once the operation is complete. |
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* |
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* We send the message to the user space daemon and the operation is |
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* performed in the daemon. |
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*/ |
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case VSS_OP_THAW: |
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case VSS_OP_FREEZE: |
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case VSS_OP_HOT_BACKUP: |
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if (vss_transaction.state < HVUTIL_READY) { |
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/* Userspace is not registered yet */ |
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pr_debug("VSS: Not ready for request.\n"); |
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vss_respond_to_host(HV_E_FAIL); |
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return; |
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} |
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pr_debug("VSS: Received request for op code: %d\n", |
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vss_transaction.msg->vss_hdr.operation); |
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vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; |
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vss_send_op(); |
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return; |
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case VSS_OP_GET_DM_INFO: |
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vss_transaction.msg->dm_info.flags = 0; |
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break; |
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default: |
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break; |
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} |
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vss_respond_to_host(0); |
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hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); |
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} |
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/* |
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* Send a response back to the host. |
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*/ |
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static void |
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vss_respond_to_host(int error) |
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{ |
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struct icmsg_hdr *icmsghdrp; |
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u32 buf_len; |
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struct vmbus_channel *channel; |
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u64 req_id; |
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/* |
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* Copy the global state for completing the transaction. Note that |
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* only one transaction can be active at a time. |
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*/ |
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buf_len = vss_transaction.recv_len; |
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channel = vss_transaction.recv_channel; |
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req_id = vss_transaction.recv_req_id; |
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icmsghdrp = (struct icmsg_hdr *) |
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&recv_buffer[sizeof(struct vmbuspipe_hdr)]; |
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if (channel->onchannel_callback == NULL) |
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/* |
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* We have raced with util driver being unloaded; |
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* silently return. |
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*/ |
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return; |
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icmsghdrp->status = error; |
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icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; |
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vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, |
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VM_PKT_DATA_INBAND, 0); |
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} |
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/* |
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* This callback is invoked when we get a VSS message from the host. |
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* The host ensures that only one VSS transaction can be active at a time. |
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*/ |
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void hv_vss_onchannelcallback(void *context) |
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{ |
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struct vmbus_channel *channel = context; |
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u32 recvlen; |
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u64 requestid; |
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struct hv_vss_msg *vss_msg; |
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int vss_srv_version; |
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struct icmsg_hdr *icmsghdrp; |
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if (vss_transaction.state > HVUTIL_READY) |
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return; |
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if (vmbus_recvpacket(channel, recv_buffer, HV_HYP_PAGE_SIZE * 2, &recvlen, &requestid)) { |
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pr_err_ratelimited("VSS request received. Could not read into recv buf\n"); |
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return; |
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} |
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if (!recvlen) |
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return; |
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/* Ensure recvlen is big enough to read header data */ |
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if (recvlen < ICMSG_HDR) { |
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pr_err_ratelimited("VSS request received. Packet length too small: %d\n", |
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recvlen); |
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return; |
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} |
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icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)]; |
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if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { |
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if (vmbus_prep_negotiate_resp(icmsghdrp, |
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recv_buffer, recvlen, |
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fw_versions, FW_VER_COUNT, |
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vss_versions, VSS_VER_COUNT, |
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NULL, &vss_srv_version)) { |
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pr_info("VSS IC version %d.%d\n", |
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vss_srv_version >> 16, |
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vss_srv_version & 0xFFFF); |
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} |
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} else if (icmsghdrp->icmsgtype == ICMSGTYPE_VSS) { |
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/* Ensure recvlen is big enough to contain hv_vss_msg */ |
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if (recvlen < ICMSG_HDR + sizeof(struct hv_vss_msg)) { |
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pr_err_ratelimited("Invalid VSS msg. Packet length too small: %u\n", |
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recvlen); |
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return; |
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} |
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vss_msg = (struct hv_vss_msg *)&recv_buffer[ICMSG_HDR]; |
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/* |
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* Stash away this global state for completing the |
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* transaction; note transactions are serialized. |
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*/ |
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vss_transaction.recv_len = recvlen; |
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vss_transaction.recv_req_id = requestid; |
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vss_transaction.msg = (struct hv_vss_msg *)vss_msg; |
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schedule_work(&vss_handle_request_work); |
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return; |
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} else { |
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pr_err_ratelimited("VSS request received. Invalid msg type: %d\n", |
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icmsghdrp->icmsgtype); |
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return; |
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} |
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icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | |
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ICMSGHDRFLAG_RESPONSE; |
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vmbus_sendpacket(channel, recv_buffer, recvlen, requestid, |
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VM_PKT_DATA_INBAND, 0); |
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} |
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static void vss_on_reset(void) |
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{ |
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if (cancel_delayed_work_sync(&vss_timeout_work)) |
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vss_respond_to_host(HV_E_FAIL); |
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vss_transaction.state = HVUTIL_DEVICE_INIT; |
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} |
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int |
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hv_vss_init(struct hv_util_service *srv) |
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{ |
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if (vmbus_proto_version < VERSION_WIN8_1) { |
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pr_warn("Integration service 'Backup (volume snapshot)'" |
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" not supported on this host version.\n"); |
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return -ENOTSUPP; |
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} |
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recv_buffer = srv->recv_buffer; |
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vss_transaction.recv_channel = srv->channel; |
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vss_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2; |
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/* |
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* When this driver loads, the user level daemon that |
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* processes the host requests may not yet be running. |
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* Defer processing channel callbacks until the daemon |
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* has registered. |
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*/ |
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vss_transaction.state = HVUTIL_DEVICE_INIT; |
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hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL, |
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vss_on_msg, vss_on_reset); |
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if (!hvt) { |
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pr_warn("VSS: Failed to initialize transport\n"); |
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return -EFAULT; |
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} |
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return 0; |
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} |
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static void hv_vss_cancel_work(void) |
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{ |
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cancel_delayed_work_sync(&vss_timeout_work); |
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cancel_work_sync(&vss_handle_request_work); |
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} |
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int hv_vss_pre_suspend(void) |
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{ |
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struct vmbus_channel *channel = vss_transaction.recv_channel; |
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struct hv_vss_msg *vss_msg; |
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/* |
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* Fake a THAW message for the user space daemon in case the daemon |
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* has frozen the file systems. It doesn't matter if there is already |
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* a message pending to be delivered to the user space since we force |
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* vss_transaction.state to be HVUTIL_READY, so the user space daemon's |
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* write() will fail with EINVAL (see vss_on_msg()), and the daemon |
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* will reset the device by closing and re-opening it. |
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*/ |
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vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); |
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if (!vss_msg) |
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return -ENOMEM; |
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tasklet_disable(&channel->callback_event); |
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vss_msg->vss_hdr.operation = VSS_OP_THAW; |
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/* Cancel any possible pending work. */ |
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hv_vss_cancel_work(); |
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/* We don't care about the return value. */ |
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hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); |
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kfree(vss_msg); |
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vss_transaction.state = HVUTIL_READY; |
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/* tasklet_enable() will be called in hv_vss_pre_resume(). */ |
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return 0; |
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} |
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int hv_vss_pre_resume(void) |
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{ |
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struct vmbus_channel *channel = vss_transaction.recv_channel; |
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tasklet_enable(&channel->callback_event); |
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return 0; |
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} |
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void hv_vss_deinit(void) |
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{ |
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vss_transaction.state = HVUTIL_DEVICE_DYING; |
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hv_vss_cancel_work(); |
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hvutil_transport_destroy(hvt); |
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}
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