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![K. Y. Srinivasan](/assets/img/avatar_default.png)
Pass the channel information to the util drivers that need to defer
reading the channel while they are processing a request. This would address
the following issue reported by Vitaly:
Commit 3cace4a616
("Drivers: hv: utils: run polling callback always in
interrupt context") removed direct *_transaction.state = HVUTIL_READY
assignments from *_handle_handshake() functions introducing the following
race: if a userspace daemon connects before we get first non-negotiation
request from the server hv_poll_channel() won't set transaction state to
HVUTIL_READY as (!channel) condition will fail, we set it to non-NULL on
the first real request from the server.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
342 lines
9.5 KiB
C
342 lines
9.5 KiB
C
/*
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* An implementation of file copy service.
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*
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* Copyright (C) 2014, Microsoft, Inc.
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*
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* Author : K. Y. Srinivasan <ksrinivasan@novell.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* details.
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/nls.h>
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#include <linux/workqueue.h>
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#include <linux/hyperv.h>
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#include <linux/sched.h>
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#include "hyperv_vmbus.h"
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#include "hv_utils_transport.h"
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#define WIN8_SRV_MAJOR 1
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#define WIN8_SRV_MINOR 1
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#define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
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/*
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* Global state maintained for transaction that is being processed.
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* For a class of integration services, including the "file copy service",
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* the specified protocol is a "request/response" protocol which means that
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* there can only be single outstanding transaction from the host at any
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* given point in time. We use this to simplify memory management in this
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* driver - we cache and process 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 hv_fcopy_hdr *fcopy_msg; /* current message */
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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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} fcopy_transaction;
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static void fcopy_respond_to_host(int error);
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static void fcopy_send_data(struct work_struct *dummy);
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static void fcopy_timeout_func(struct work_struct *dummy);
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static DECLARE_DELAYED_WORK(fcopy_timeout_work, fcopy_timeout_func);
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static DECLARE_WORK(fcopy_send_work, fcopy_send_data);
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static const char fcopy_devname[] = "vmbus/hv_fcopy";
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static u8 *recv_buffer;
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static struct hvutil_transport *hvt;
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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 void fcopy_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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fcopy_transaction.state = HVUTIL_READY;
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hv_fcopy_onchannelcallback(channel);
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}
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static void fcopy_timeout_func(struct work_struct *dummy)
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{
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/*
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* If the timer fires, the user-mode component has not responded;
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* process the pending transaction.
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*/
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fcopy_respond_to_host(HV_E_FAIL);
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hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
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}
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static int fcopy_handle_handshake(u32 version)
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{
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u32 our_ver = FCOPY_CURRENT_VERSION;
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switch (version) {
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case FCOPY_VERSION_0:
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/* Daemon doesn't expect us to reply */
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dm_reg_value = version;
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break;
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case FCOPY_VERSION_1:
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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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return -EFAULT;
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dm_reg_value = version;
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break;
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default:
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/*
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* For now we will fail the registration.
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* If and when we have multiple versions to
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* deal with, we will be backward compatible.
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* We will add this code when needed.
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*/
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return -EINVAL;
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}
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pr_debug("FCP: userspace daemon ver. %d registered\n", version);
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hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
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return 0;
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}
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static void fcopy_send_data(struct work_struct *dummy)
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{
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struct hv_start_fcopy *smsg_out = NULL;
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int operation = fcopy_transaction.fcopy_msg->operation;
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struct hv_start_fcopy *smsg_in;
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void *out_src;
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int rc, out_len;
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/*
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* The strings sent from the host are encoded in
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* in utf16; convert it to utf8 strings.
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* The host assures us that the utf16 strings will not exceed
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* the max lengths specified. We will however, reserve room
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* for the string terminating character - in the utf16s_utf8s()
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* function we limit the size of the buffer where the converted
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* string is placed to W_MAX_PATH -1 to guarantee
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* that the strings can be properly terminated!
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*/
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switch (operation) {
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case START_FILE_COPY:
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out_len = sizeof(struct hv_start_fcopy);
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smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
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if (!smsg_out)
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return;
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smsg_out->hdr.operation = operation;
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smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
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utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
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UTF16_LITTLE_ENDIAN,
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(__u8 *)&smsg_out->file_name, W_MAX_PATH - 1);
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utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
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UTF16_LITTLE_ENDIAN,
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(__u8 *)&smsg_out->path_name, W_MAX_PATH - 1);
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smsg_out->copy_flags = smsg_in->copy_flags;
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smsg_out->file_size = smsg_in->file_size;
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out_src = smsg_out;
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break;
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default:
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out_src = fcopy_transaction.fcopy_msg;
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out_len = fcopy_transaction.recv_len;
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break;
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}
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fcopy_transaction.state = HVUTIL_USERSPACE_REQ;
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rc = hvutil_transport_send(hvt, out_src, out_len);
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if (rc) {
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pr_debug("FCP: failed to communicate to the daemon: %d\n", rc);
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if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
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fcopy_respond_to_host(HV_E_FAIL);
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fcopy_transaction.state = HVUTIL_READY;
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}
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}
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kfree(smsg_out);
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return;
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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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fcopy_respond_to_host(int error)
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{
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struct icmsg_hdr *icmsghdr;
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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. This is guaranteed
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* by the file copy protocol implemented by the host. Furthermore,
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* the "transaction active" state we maintain ensures that there can
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* only be one active transaction at a time.
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*/
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buf_len = fcopy_transaction.recv_len;
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channel = fcopy_transaction.recv_channel;
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req_id = fcopy_transaction.recv_req_id;
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icmsghdr = (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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icmsghdr->status = error;
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icmsghdr->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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void hv_fcopy_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_fcopy_hdr *fcopy_msg;
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struct icmsg_hdr *icmsghdr;
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struct icmsg_negotiate *negop = NULL;
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int util_fw_version;
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int fcopy_srv_version;
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if (fcopy_transaction.state > HVUTIL_READY)
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return;
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vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
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&requestid);
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if (recvlen <= 0)
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return;
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icmsghdr = (struct icmsg_hdr *)&recv_buffer[
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sizeof(struct vmbuspipe_hdr)];
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if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
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util_fw_version = UTIL_FW_VERSION;
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fcopy_srv_version = WIN8_SRV_VERSION;
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vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
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util_fw_version, fcopy_srv_version);
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} else {
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fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
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sizeof(struct vmbuspipe_hdr) +
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sizeof(struct 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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fcopy_transaction.recv_len = recvlen;
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fcopy_transaction.recv_req_id = requestid;
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fcopy_transaction.fcopy_msg = fcopy_msg;
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if (fcopy_transaction.state < HVUTIL_READY) {
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/* Userspace is not registered yet */
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fcopy_respond_to_host(HV_E_FAIL);
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return;
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}
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fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
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/*
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* Send the information to the user-level daemon.
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*/
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schedule_work(&fcopy_send_work);
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schedule_delayed_work(&fcopy_timeout_work,
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HV_UTIL_TIMEOUT * HZ);
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return;
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}
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icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | 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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/* Callback when data is received from userspace */
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static int fcopy_on_msg(void *msg, int len)
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{
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int *val = (int *)msg;
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if (len != sizeof(int))
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return -EINVAL;
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if (fcopy_transaction.state == HVUTIL_DEVICE_INIT)
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return fcopy_handle_handshake(*val);
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if (fcopy_transaction.state != HVUTIL_USERSPACE_REQ)
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return -EINVAL;
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/*
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* Complete the transaction by forwarding the result
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* to the host. But first, cancel the timeout.
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*/
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if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
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fcopy_transaction.state = HVUTIL_USERSPACE_RECV;
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fcopy_respond_to_host(*val);
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hv_poll_channel(fcopy_transaction.recv_channel,
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fcopy_poll_wrapper);
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}
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return 0;
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}
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static void fcopy_on_reset(void)
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{
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/*
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* The daemon has exited; reset the state.
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*/
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fcopy_transaction.state = HVUTIL_DEVICE_INIT;
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if (cancel_delayed_work_sync(&fcopy_timeout_work))
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fcopy_respond_to_host(HV_E_FAIL);
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}
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int hv_fcopy_init(struct hv_util_service *srv)
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{
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recv_buffer = srv->recv_buffer;
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fcopy_transaction.recv_channel = srv->channel;
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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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fcopy_transaction.state = HVUTIL_DEVICE_INIT;
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hvt = hvutil_transport_init(fcopy_devname, 0, 0,
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fcopy_on_msg, fcopy_on_reset);
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if (!hvt)
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return -EFAULT;
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return 0;
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}
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void hv_fcopy_deinit(void)
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{
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fcopy_transaction.state = HVUTIL_DEVICE_DYING;
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cancel_delayed_work_sync(&fcopy_timeout_work);
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hvutil_transport_destroy(hvt);
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}
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