OSCL-LXR linux-6.0.1/​drivers/​scsi/​storvsc_drv.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2009, Microsoft Corporation.
  *
  * Authors:
  *   Haiyang Zhang <haiyangz@microsoft.com>
  *   Hank Janssen  <hjanssen@microsoft.com>
  *   K. Y. Srinivasan <kys@microsoft.com>
  */
 
 #include <linux/kernel.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
 #include <linux/completion.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/hyperv.h>
 #include <linux/blkdev.h>
 #include <linux/dma-mapping.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_tcq.h>
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_devinfo.h>
 #include <scsi/scsi_dbg.h>
 #include <scsi/scsi_transport_fc.h>
 #include <scsi/scsi_transport.h>
 
 /*
  * All wire protocol details (storage protocol between the guest and the host)
  * are consolidated here.
  *
  * Begin protocol definitions.
  */
 
 /*
  * Version history:
  * V1 Beta: 0.1
  * V1 RC < 2008/1/31: 1.0
  * V1 RC > 2008/1/31:  2.0
  * Win7: 4.2
  * Win8: 5.1
  * Win8.1: 6.0
  * Win10: 6.2
  */
 
 #define VMSTOR_PROTO_VERSION(MAJOR_, MINOR_)    ((((MAJOR_) & 0xff) << 8) | \
                         (((MINOR_) & 0xff)))
 #define VMSTOR_PROTO_VERSION_WIN6   VMSTOR_PROTO_VERSION(2, 0)
 #define VMSTOR_PROTO_VERSION_WIN7   VMSTOR_PROTO_VERSION(4, 2)
 #define VMSTOR_PROTO_VERSION_WIN8   VMSTOR_PROTO_VERSION(5, 1)
 #define VMSTOR_PROTO_VERSION_WIN8_1 VMSTOR_PROTO_VERSION(6, 0)
 #define VMSTOR_PROTO_VERSION_WIN10  VMSTOR_PROTO_VERSION(6, 2)
 
 /*  Packet structure describing virtual storage requests. */
 enum vstor_packet_operation {
     VSTOR_OPERATION_COMPLETE_IO     = 1,
     VSTOR_OPERATION_REMOVE_DEVICE       = 2,
     VSTOR_OPERATION_EXECUTE_SRB     = 3,
     VSTOR_OPERATION_RESET_LUN       = 4,
     VSTOR_OPERATION_RESET_ADAPTER       = 5,
     VSTOR_OPERATION_RESET_BUS       = 6,
     VSTOR_OPERATION_BEGIN_INITIALIZATION    = 7,
     VSTOR_OPERATION_END_INITIALIZATION  = 8,
     VSTOR_OPERATION_QUERY_PROTOCOL_VERSION  = 9,
     VSTOR_OPERATION_QUERY_PROPERTIES    = 10,
     VSTOR_OPERATION_ENUMERATE_BUS       = 11,
     VSTOR_OPERATION_FCHBA_DATA              = 12,
     VSTOR_OPERATION_CREATE_SUB_CHANNELS     = 13,
     VSTOR_OPERATION_MAXIMUM                 = 13
 };
 
 /*
  * WWN packet for Fibre Channel HBA
  */
 
 struct hv_fc_wwn_packet {
     u8  primary_active;
     u8  reserved1[3];
     u8  primary_port_wwn[8];
     u8  primary_node_wwn[8];
     u8  secondary_port_wwn[8];
     u8  secondary_node_wwn[8];
 };
 
 
 
 /*
  * SRB Flag Bits
  */
 
 #define SRB_FLAGS_QUEUE_ACTION_ENABLE       0x00000002
 #define SRB_FLAGS_DISABLE_DISCONNECT        0x00000004
 #define SRB_FLAGS_DISABLE_SYNCH_TRANSFER    0x00000008
 #define SRB_FLAGS_BYPASS_FROZEN_QUEUE       0x00000010
 #define SRB_FLAGS_DISABLE_AUTOSENSE     0x00000020
 #define SRB_FLAGS_DATA_IN           0x00000040
 #define SRB_FLAGS_DATA_OUT          0x00000080
 #define SRB_FLAGS_NO_DATA_TRANSFER      0x00000000
 #define SRB_FLAGS_UNSPECIFIED_DIRECTION (SRB_FLAGS_DATA_IN | SRB_FLAGS_DATA_OUT)
 #define SRB_FLAGS_NO_QUEUE_FREEZE       0x00000100
 #define SRB_FLAGS_ADAPTER_CACHE_ENABLE      0x00000200
 #define SRB_FLAGS_FREE_SENSE_BUFFER     0x00000400
 
 /*
  * This flag indicates the request is part of the workflow for processing a D3.
  */
 #define SRB_FLAGS_D3_PROCESSING         0x00000800
 #define SRB_FLAGS_IS_ACTIVE         0x00010000
 #define SRB_FLAGS_ALLOCATED_FROM_ZONE       0x00020000
 #define SRB_FLAGS_SGLIST_FROM_POOL      0x00040000
 #define SRB_FLAGS_BYPASS_LOCKED_QUEUE       0x00080000
 #define SRB_FLAGS_NO_KEEP_AWAKE         0x00100000
 #define SRB_FLAGS_PORT_DRIVER_ALLOCSENSE    0x00200000
 #define SRB_FLAGS_PORT_DRIVER_SENSEHASPORT  0x00400000
 #define SRB_FLAGS_DONT_START_NEXT_PACKET    0x00800000
 #define SRB_FLAGS_PORT_DRIVER_RESERVED      0x0F000000
 #define SRB_FLAGS_CLASS_DRIVER_RESERVED     0xF0000000
 
 #define SP_UNTAGGED         ((unsigned char) ~0)
 #define SRB_SIMPLE_TAG_REQUEST      0x20
 
 /*
  * Platform neutral description of a scsi request -
  * this remains the same across the write regardless of 32/64 bit
  * note: it's patterned off the SCSI_PASS_THROUGH structure
  */
 #define STORVSC_MAX_CMD_LEN         0x10
 
 /* Sense buffer size is the same for all versions since Windows 8 */
 #define STORVSC_SENSE_BUFFER_SIZE       0x14
 #define STORVSC_MAX_BUF_LEN_WITH_PADDING    0x14
 
 /*
  * The storage protocol version is determined during the
  * initial exchange with the host.  It will indicate which
  * storage functionality is available in the host.
 */
 static int vmstor_proto_version;
 
 #define STORVSC_LOGGING_NONE    0
 #define STORVSC_LOGGING_ERROR   1
 #define STORVSC_LOGGING_WARN    2
 
 static int logging_level = STORVSC_LOGGING_ERROR;
 module_param(logging_level, int, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(logging_level,
     "Logging level, 0 - None, 1 - Error (default), 2 - Warning.");
 
 static inline bool do_logging(int level)
 {
     return logging_level >= level;
 }
 
 #define storvsc_log(dev, level, fmt, ...)           \
 do {                                \
     if (do_logging(level))                  \
         dev_warn(&(dev)->device, fmt, ##__VA_ARGS__);   \
 } while (0)
 
 struct vmscsi_request {
     u16 length;
     u8 srb_status;
     u8 scsi_status;
 
     u8  port_number;
     u8  path_id;
     u8  target_id;
     u8  lun;
 
     u8  cdb_length;
     u8  sense_info_length;
     u8  data_in;
     u8  reserved;
 
     u32 data_transfer_length;
 
     union {
         u8 cdb[STORVSC_MAX_CMD_LEN];
         u8 sense_data[STORVSC_SENSE_BUFFER_SIZE];
         u8 reserved_array[STORVSC_MAX_BUF_LEN_WITH_PADDING];
     };
     /*
      * The following was added in win8.
      */
     u16 reserve;
     u8  queue_tag;
     u8  queue_action;
     u32 srb_flags;
     u32 time_out_value;
     u32 queue_sort_ey;
 
 } __attribute((packed));
 
 /*
  * The list of windows version in order of preference.
  */
 
 static const int protocol_version[] = {
         VMSTOR_PROTO_VERSION_WIN10,
         VMSTOR_PROTO_VERSION_WIN8_1,
         VMSTOR_PROTO_VERSION_WIN8,
 };
 
 
 /*
  * This structure is sent during the initialization phase to get the different
  * properties of the channel.
  */
 
 #define STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL      0x1
 
 struct vmstorage_channel_properties {
     u32 reserved;
     u16 max_channel_cnt;
     u16 reserved1;
 
     u32 flags;
     u32   max_transfer_bytes;
 
     u64  reserved2;
 } __packed;
 
 /*  This structure is sent during the storage protocol negotiations. */
 struct vmstorage_protocol_version {
     /* Major (MSW) and minor (LSW) version numbers. */
     u16 major_minor;
 
     /*
      * Revision number is auto-incremented whenever this file is changed
      * (See FILL_VMSTOR_REVISION macro above).  Mismatch does not
      * definitely indicate incompatibility--but it does indicate mismatched
      * builds.
      * This is only used on the windows side. Just set it to 0.
      */
     u16 revision;
 } __packed;
 
 /* Channel Property Flags */
 #define STORAGE_CHANNEL_REMOVABLE_FLAG      0x1
 #define STORAGE_CHANNEL_EMULATED_IDE_FLAG   0x2
 
 struct vstor_packet {
     /* Requested operation type */
     enum vstor_packet_operation operation;
 
     /*  Flags - see below for values */
     u32 flags;
 
     /* Status of the request returned from the server side. */
     u32 status;
 
     /* Data payload area */
     union {
         /*
          * Structure used to forward SCSI commands from the
          * client to the server.
          */
         struct vmscsi_request vm_srb;
 
         /* Structure used to query channel properties. */
         struct vmstorage_channel_properties storage_channel_properties;
 
         /* Used during version negotiations. */
         struct vmstorage_protocol_version version;
 
         /* Fibre channel address packet */
         struct hv_fc_wwn_packet wwn_packet;
 
         /* Number of sub-channels to create */
         u16 sub_channel_count;
 
         /* This will be the maximum of the union members */
         u8  buffer[0x34];
     };
 } __packed;
 
 /*
  * Packet Flags:
  *
  * This flag indicates that the server should send back a completion for this
  * packet.
  */
 
 #define REQUEST_COMPLETION_FLAG 0x1
 
 /* Matches Windows-end */
 enum storvsc_request_type {
     WRITE_TYPE = 0,
     READ_TYPE,
     UNKNOWN_TYPE,
 };
 
 /*
  * SRB status codes and masks; a subset of the codes used here.
  */
 
 #define SRB_STATUS_AUTOSENSE_VALID  0x80
 #define SRB_STATUS_QUEUE_FROZEN     0x40
 #define SRB_STATUS_INVALID_LUN  0x20
 #define SRB_STATUS_SUCCESS  0x01
 #define SRB_STATUS_ABORTED  0x02
 #define SRB_STATUS_ERROR    0x04
 #define SRB_STATUS_DATA_OVERRUN 0x12
 
 #define SRB_STATUS(status) \
     (status & ~(SRB_STATUS_AUTOSENSE_VALID | SRB_STATUS_QUEUE_FROZEN))
 /*
  * This is the end of Protocol specific defines.
  */
 
 static int storvsc_ringbuffer_size = (128 * 1024);
 static u32 max_outstanding_req_per_channel;
 static int storvsc_change_queue_depth(struct scsi_device *sdev, int queue_depth);
 
 static int storvsc_vcpus_per_sub_channel = 4;
 static unsigned int storvsc_max_hw_queues;
 
 module_param(storvsc_ringbuffer_size, int, S_IRUGO);
 MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size (bytes)");
 
 module_param(storvsc_max_hw_queues, uint, 0644);
 MODULE_PARM_DESC(storvsc_max_hw_queues, "Maximum number of hardware queues");
 
 module_param(storvsc_vcpus_per_sub_channel, int, S_IRUGO);
 MODULE_PARM_DESC(storvsc_vcpus_per_sub_channel, "Ratio of VCPUs to subchannels");
 
 static int ring_avail_percent_lowater = 10;
 module_param(ring_avail_percent_lowater, int, S_IRUGO);
 MODULE_PARM_DESC(ring_avail_percent_lowater,
         "Select a channel if available ring size > this in percent");
 
 /*
  * Timeout in seconds for all devices managed by this driver.
  */
 static int storvsc_timeout = 180;
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
 static struct scsi_transport_template *fc_transport_template;
 #endif
 
 static struct scsi_host_template scsi_driver;
 static void storvsc_on_channel_callback(void *context);
 
 #define STORVSC_MAX_LUNS_PER_TARGET         255
 #define STORVSC_MAX_TARGETS             2
 #define STORVSC_MAX_CHANNELS                8
 
 #define STORVSC_FC_MAX_LUNS_PER_TARGET          255
 #define STORVSC_FC_MAX_TARGETS              128
 #define STORVSC_FC_MAX_CHANNELS             8
 
 #define STORVSC_IDE_MAX_LUNS_PER_TARGET         64
 #define STORVSC_IDE_MAX_TARGETS             1
 #define STORVSC_IDE_MAX_CHANNELS            1
 
 /*
  * Upper bound on the size of a storvsc packet.
  */
 #define STORVSC_MAX_PKT_SIZE (sizeof(struct vmpacket_descriptor) +\
                   sizeof(struct vstor_packet))
 
 struct storvsc_cmd_request {
     struct scsi_cmnd *cmd;
 
     struct hv_device *device;
 
     /* Synchronize the request/response if needed */
     struct completion wait_event;
 
     struct vmbus_channel_packet_multipage_buffer mpb;
     struct vmbus_packet_mpb_array *payload;
     u32 payload_sz;
 
     struct vstor_packet vstor_packet;
 };
 
 
 /* A storvsc device is a device object that contains a vmbus channel */
 struct storvsc_device {
     struct hv_device *device;
 
     bool     destroy;
     bool     drain_notify;
     atomic_t num_outstanding_req;
     struct Scsi_Host *host;
 
     wait_queue_head_t waiting_to_drain;
 
     /*
      * Each unique Port/Path/Target represents 1 channel ie scsi
      * controller. In reality, the pathid, targetid is always 0
      * and the port is set by us
      */
     unsigned int port_number;
     unsigned char path_id;
     unsigned char target_id;
 
     /*
      * Max I/O, the device can support.
      */
     u32   max_transfer_bytes;
     /*
      * Number of sub-channels we will open.
      */
     u16 num_sc;
     struct vmbus_channel **stor_chns;
     /*
      * Mask of CPUs bound to subchannels.
      */
     struct cpumask alloced_cpus;
     /*
      * Serializes modifications of stor_chns[] from storvsc_do_io()
      * and storvsc_change_target_cpu().
      */
     spinlock_t lock;
     /* Used for vsc/vsp channel reset process */
     struct storvsc_cmd_request init_request;
     struct storvsc_cmd_request reset_request;
     /*
      * Currently active port and node names for FC devices.
      */
     u64 node_name;
     u64 port_name;
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     struct fc_rport *rport;
 #endif
 };
 
 struct hv_host_device {
     struct hv_device *dev;
     unsigned int port;
     unsigned char path;
     unsigned char target;
     struct workqueue_struct *handle_error_wq;
     struct work_struct host_scan_work;
     struct Scsi_Host *host;
 };
 
 struct storvsc_scan_work {
     struct work_struct work;
     struct Scsi_Host *host;
     u8 lun;
     u8 tgt_id;
 };
 
 static void storvsc_device_scan(struct work_struct *work)
 {
     struct storvsc_scan_work *wrk;
     struct scsi_device *sdev;
 
     wrk = container_of(work, struct storvsc_scan_work, work);
 
     sdev = scsi_device_lookup(wrk->host, 0, wrk->tgt_id, wrk->lun);
     if (!sdev)
         goto done;
     scsi_rescan_device(&sdev->sdev_gendev);
     scsi_device_put(sdev);
 
 done:
     kfree(wrk);
 }
 
 static void storvsc_host_scan(struct work_struct *work)
 {
     struct Scsi_Host *host;
     struct scsi_device *sdev;
     struct hv_host_device *host_device =
         container_of(work, struct hv_host_device, host_scan_work);
 
     host = host_device->host;
     /*
      * Before scanning the host, first check to see if any of the
      * currently known devices have been hot removed. We issue a
      * "unit ready" command against all currently known devices.
      * This I/O will result in an error for devices that have been
      * removed. As part of handling the I/O error, we remove the device.
      *
      * When a LUN is added or removed, the host sends us a signal to
      * scan the host. Thus we are forced to discover the LUNs that
      * may have been removed this way.
      */
     mutex_lock(&host->scan_mutex);
     shost_for_each_device(sdev, host)
         scsi_test_unit_ready(sdev, 1, 1, NULL);
     mutex_unlock(&host->scan_mutex);
     /*
      * Now scan the host to discover LUNs that may have been added.
      */
     scsi_scan_host(host);
 }
 
 static void storvsc_remove_lun(struct work_struct *work)
 {
     struct storvsc_scan_work *wrk;
     struct scsi_device *sdev;
 
     wrk = container_of(work, struct storvsc_scan_work, work);
     if (!scsi_host_get(wrk->host))
         goto done;
 
     sdev = scsi_device_lookup(wrk->host, 0, wrk->tgt_id, wrk->lun);
 
     if (sdev) {
         scsi_remove_device(sdev);
         scsi_device_put(sdev);
     }
     scsi_host_put(wrk->host);
 
 done:
     kfree(wrk);
 }
 
 
 /*
  * We can get incoming messages from the host that are not in response to
  * messages that we have sent out. An example of this would be messages
  * received by the guest to notify dynamic addition/removal of LUNs. To
  * deal with potential race conditions where the driver may be in the
  * midst of being unloaded when we might receive an unsolicited message
  * from the host, we have implemented a mechanism to gurantee sequential
  * consistency:
  *
  * 1) Once the device is marked as being destroyed, we will fail all
  *    outgoing messages.
  * 2) We permit incoming messages when the device is being destroyed,
  *    only to properly account for messages already sent out.
  */
 
 static inline struct storvsc_device *get_out_stor_device(
                     struct hv_device *device)
 {
     struct storvsc_device *stor_device;
 
     stor_device = hv_get_drvdata(device);
 
     if (stor_device && stor_device->destroy)
         stor_device = NULL;
 
     return stor_device;
 }
 
 
 static inline void storvsc_wait_to_drain(struct storvsc_device *dev)
 {
     dev->drain_notify = true;
     wait_event(dev->waiting_to_drain,
            atomic_read(&dev->num_outstanding_req) == 0);
     dev->drain_notify = false;
 }
 
 static inline struct storvsc_device *get_in_stor_device(
                     struct hv_device *device)
 {
     struct storvsc_device *stor_device;
 
     stor_device = hv_get_drvdata(device);
 
     if (!stor_device)
         goto get_in_err;
 
     /*
      * If the device is being destroyed; allow incoming
      * traffic only to cleanup outstanding requests.
      */
 
     if (stor_device->destroy  &&
         (atomic_read(&stor_device->num_outstanding_req) == 0))
         stor_device = NULL;
 
 get_in_err:
     return stor_device;
 
 }
 
 static void storvsc_change_target_cpu(struct vmbus_channel *channel, u32 old,
                       u32 new)
 {
     struct storvsc_device *stor_device;
     struct vmbus_channel *cur_chn;
     bool old_is_alloced = false;
     struct hv_device *device;
     unsigned long flags;
     int cpu;
 
     device = channel->primary_channel ?
             channel->primary_channel->device_obj
                 : channel->device_obj;
     stor_device = get_out_stor_device(device);
     if (!stor_device)
         return;
 
     /* See storvsc_do_io() -> get_og_chn(). */
     spin_lock_irqsave(&stor_device->lock, flags);
 
     /*
      * Determines if the storvsc device has other channels assigned to
      * the "old" CPU to update the alloced_cpus mask and the stor_chns
      * array.
      */
     if (device->channel != channel && device->channel->target_cpu == old) {
         cur_chn = device->channel;
         old_is_alloced = true;
         goto old_is_alloced;
     }
     list_for_each_entry(cur_chn, &device->channel->sc_list, sc_list) {
         if (cur_chn == channel)
             continue;
         if (cur_chn->target_cpu == old) {
             old_is_alloced = true;
             goto old_is_alloced;
         }
     }
 
 old_is_alloced:
     if (old_is_alloced)
         WRITE_ONCE(stor_device->stor_chns[old], cur_chn);
     else
         cpumask_clear_cpu(old, &stor_device->alloced_cpus);
 
     /* "Flush" the stor_chns array. */
     for_each_possible_cpu(cpu) {
         if (stor_device->stor_chns[cpu] && !cpumask_test_cpu(
                     cpu, &stor_device->alloced_cpus))
             WRITE_ONCE(stor_device->stor_chns[cpu], NULL);
     }
 
     WRITE_ONCE(stor_device->stor_chns[new], channel);
     cpumask_set_cpu(new, &stor_device->alloced_cpus);
 
     spin_unlock_irqrestore(&stor_device->lock, flags);
 }
 
 static u64 storvsc_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
 {
     struct storvsc_cmd_request *request =
         (struct storvsc_cmd_request *)(unsigned long)rqst_addr;
 
     if (rqst_addr == VMBUS_RQST_INIT)
         return VMBUS_RQST_INIT;
     if (rqst_addr == VMBUS_RQST_RESET)
         return VMBUS_RQST_RESET;
 
     /*
      * Cannot return an ID of 0, which is reserved for an unsolicited
      * message from Hyper-V.
      */
     return (u64)blk_mq_unique_tag(scsi_cmd_to_rq(request->cmd)) + 1;
 }
 
 static void handle_sc_creation(struct vmbus_channel *new_sc)
 {
     struct hv_device *device = new_sc->primary_channel->device_obj;
     struct device *dev = &device->device;
     struct storvsc_device *stor_device;
     struct vmstorage_channel_properties props;
     int ret;
 
     stor_device = get_out_stor_device(device);
     if (!stor_device)
         return;
 
     memset(&props, 0, sizeof(struct vmstorage_channel_properties));
     new_sc->max_pkt_size = STORVSC_MAX_PKT_SIZE;
 
     new_sc->next_request_id_callback = storvsc_next_request_id;
 
     ret = vmbus_open(new_sc,
              storvsc_ringbuffer_size,
              storvsc_ringbuffer_size,
              (void *)&props,
              sizeof(struct vmstorage_channel_properties),
              storvsc_on_channel_callback, new_sc);
 
     /* In case vmbus_open() fails, we don't use the sub-channel. */
     if (ret != 0) {
         dev_err(dev, "Failed to open sub-channel: err=%d\n", ret);
         return;
     }
 
     new_sc->change_target_cpu_callback = storvsc_change_target_cpu;
 
     /* Add the sub-channel to the array of available channels. */
     stor_device->stor_chns[new_sc->target_cpu] = new_sc;
     cpumask_set_cpu(new_sc->target_cpu, &stor_device->alloced_cpus);
 }
 
 static void  handle_multichannel_storage(struct hv_device *device, int max_chns)
 {
     struct device *dev = &device->device;
     struct storvsc_device *stor_device;
     int num_sc;
     struct storvsc_cmd_request *request;
     struct vstor_packet *vstor_packet;
     int ret, t;
 
     /*
      * If the number of CPUs is artificially restricted, such as
      * with maxcpus=1 on the kernel boot line, Hyper-V could offer
      * sub-channels >= the number of CPUs. These sub-channels
      * should not be created. The primary channel is already created
      * and assigned to one CPU, so check against # CPUs - 1.
      */
     num_sc = min((int)(num_online_cpus() - 1), max_chns);
     if (!num_sc)
         return;
 
     stor_device = get_out_stor_device(device);
     if (!stor_device)
         return;
 
     stor_device->num_sc = num_sc;
     request = &stor_device->init_request;
     vstor_packet = &request->vstor_packet;
 
     /*
      * Establish a handler for dealing with subchannels.
      */
     vmbus_set_sc_create_callback(device->channel, handle_sc_creation);
 
     /*
      * Request the host to create sub-channels.
      */
     memset(request, 0, sizeof(struct storvsc_cmd_request));
     init_completion(&request->wait_event);
     vstor_packet->operation = VSTOR_OPERATION_CREATE_SUB_CHANNELS;
     vstor_packet->flags = REQUEST_COMPLETION_FLAG;
     vstor_packet->sub_channel_count = num_sc;
 
     ret = vmbus_sendpacket(device->channel, vstor_packet,
                    sizeof(struct vstor_packet),
                    VMBUS_RQST_INIT,
                    VM_PKT_DATA_INBAND,
                    VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 
     if (ret != 0) {
         dev_err(dev, "Failed to create sub-channel: err=%d\n", ret);
         return;
     }
 
     t = wait_for_completion_timeout(&request->wait_event, 10*HZ);
     if (t == 0) {
         dev_err(dev, "Failed to create sub-channel: timed out\n");
         return;
     }
 
     if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
         vstor_packet->status != 0) {
         dev_err(dev, "Failed to create sub-channel: op=%d, sts=%d\n",
             vstor_packet->operation, vstor_packet->status);
         return;
     }
 
     /*
      * We need to do nothing here, because vmbus_process_offer()
      * invokes channel->sc_creation_callback, which will open and use
      * the sub-channel(s).
      */
 }
 
 static void cache_wwn(struct storvsc_device *stor_device,
               struct vstor_packet *vstor_packet)
 {
     /*
      * Cache the currently active port and node ww names.
      */
     if (vstor_packet->wwn_packet.primary_active) {
         stor_device->node_name =
             wwn_to_u64(vstor_packet->wwn_packet.primary_node_wwn);
         stor_device->port_name =
             wwn_to_u64(vstor_packet->wwn_packet.primary_port_wwn);
     } else {
         stor_device->node_name =
             wwn_to_u64(vstor_packet->wwn_packet.secondary_node_wwn);
         stor_device->port_name =
             wwn_to_u64(vstor_packet->wwn_packet.secondary_port_wwn);
     }
 }
 
 
 static int storvsc_execute_vstor_op(struct hv_device *device,
                     struct storvsc_cmd_request *request,
                     bool status_check)
 {
     struct storvsc_device *stor_device;
     struct vstor_packet *vstor_packet;
     int ret, t;
 
     stor_device = get_out_stor_device(device);
     if (!stor_device)
         return -ENODEV;
 
     vstor_packet = &request->vstor_packet;
 
     init_completion(&request->wait_event);
     vstor_packet->flags = REQUEST_COMPLETION_FLAG;
 
     ret = vmbus_sendpacket(device->channel, vstor_packet,
                    sizeof(struct vstor_packet),
                    VMBUS_RQST_INIT,
                    VM_PKT_DATA_INBAND,
                    VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
     if (ret != 0)
         return ret;
 
     t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
     if (t == 0)
         return -ETIMEDOUT;
 
     if (!status_check)
         return ret;
 
     if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
         vstor_packet->status != 0)
         return -EINVAL;
 
     return ret;
 }
 
 static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 {
     struct storvsc_device *stor_device;
     struct storvsc_cmd_request *request;
     struct vstor_packet *vstor_packet;
     int ret, i;
     int max_chns;
     bool process_sub_channels = false;
 
     stor_device = get_out_stor_device(device);
     if (!stor_device)
         return -ENODEV;
 
     request = &stor_device->init_request;
     vstor_packet = &request->vstor_packet;
 
     /*
      * Now, initiate the vsc/vsp initialization protocol on the open
      * channel
      */
     memset(request, 0, sizeof(struct storvsc_cmd_request));
     vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
     ret = storvsc_execute_vstor_op(device, request, true);
     if (ret)
         return ret;
     /*
      * Query host supported protocol version.
      */
 
     for (i = 0; i < ARRAY_SIZE(protocol_version); i++) {
         /* reuse the packet for version range supported */
         memset(vstor_packet, 0, sizeof(struct vstor_packet));
         vstor_packet->operation =
             VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
 
         vstor_packet->version.major_minor = protocol_version[i];
 
         /*
          * The revision number is only used in Windows; set it to 0.
          */
         vstor_packet->version.revision = 0;
         ret = storvsc_execute_vstor_op(device, request, false);
         if (ret != 0)
             return ret;
 
         if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO)
             return -EINVAL;
 
         if (vstor_packet->status == 0) {
             vmstor_proto_version = protocol_version[i];
 
             break;
         }
     }
 
     if (vstor_packet->status != 0) {
         dev_err(&device->device, "Obsolete Hyper-V version\n");
         return -EINVAL;
     }
 
 
     memset(vstor_packet, 0, sizeof(struct vstor_packet));
     vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
     ret = storvsc_execute_vstor_op(device, request, true);
     if (ret != 0)
         return ret;
 
     /*
      * Check to see if multi-channel support is there.
      * Hosts that implement protocol version of 5.1 and above
      * support multi-channel.
      */
     max_chns = vstor_packet->storage_channel_properties.max_channel_cnt;
 
     /*
      * Allocate state to manage the sub-channels.
      * We allocate an array based on the numbers of possible CPUs
      * (Hyper-V does not support cpu online/offline).
      * This Array will be sparseley populated with unique
      * channels - primary + sub-channels.
      * We will however populate all the slots to evenly distribute
      * the load.
      */
     stor_device->stor_chns = kcalloc(num_possible_cpus(), sizeof(void *),
                      GFP_KERNEL);
     if (stor_device->stor_chns == NULL)
         return -ENOMEM;
 
     device->channel->change_target_cpu_callback = storvsc_change_target_cpu;
 
     stor_device->stor_chns[device->channel->target_cpu] = device->channel;
     cpumask_set_cpu(device->channel->target_cpu,
             &stor_device->alloced_cpus);
 
     if (vstor_packet->storage_channel_properties.flags &
         STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL)
         process_sub_channels = true;
 
     stor_device->max_transfer_bytes =
         vstor_packet->storage_channel_properties.max_transfer_bytes;
 
     if (!is_fc)
         goto done;
 
     /*
      * For FC devices retrieve FC HBA data.
      */
     memset(vstor_packet, 0, sizeof(struct vstor_packet));
     vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
     ret = storvsc_execute_vstor_op(device, request, true);
     if (ret != 0)
         return ret;
 
     /*
      * Cache the currently active port and node ww names.
      */
     cache_wwn(stor_device, vstor_packet);
 
 done:
 
     memset(vstor_packet, 0, sizeof(struct vstor_packet));
     vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
     ret = storvsc_execute_vstor_op(device, request, true);
     if (ret != 0)
         return ret;
 
     if (process_sub_channels)
         handle_multichannel_storage(device, max_chns);
 
     return ret;
 }
 
 static void storvsc_handle_error(struct vmscsi_request *vm_srb,
                 struct scsi_cmnd *scmnd,
                 struct Scsi_Host *host,
                 u8 asc, u8 ascq)
 {
     struct storvsc_scan_work *wrk;
     void (*process_err_fn)(struct work_struct *work);
     struct hv_host_device *host_dev = shost_priv(host);
 
     /*
      * In some situations, Hyper-V sets multiple bits in the
      * srb_status, such as ABORTED and ERROR. So process them
      * individually, with the most specific bits first.
      */
 
     if (vm_srb->srb_status & SRB_STATUS_INVALID_LUN) {
         set_host_byte(scmnd, DID_NO_CONNECT);
         process_err_fn = storvsc_remove_lun;
         goto do_work;
     }
 
     if (vm_srb->srb_status & SRB_STATUS_ABORTED) {
         if (vm_srb->srb_status & SRB_STATUS_AUTOSENSE_VALID &&
             /* Capacity data has changed */
             (asc == 0x2a) && (ascq == 0x9)) {
             process_err_fn = storvsc_device_scan;
             /*
              * Retry the I/O that triggered this.
              */
             set_host_byte(scmnd, DID_REQUEUE);
             goto do_work;
         }
     }
 
     if (vm_srb->srb_status & SRB_STATUS_ERROR) {
         /*
          * Let upper layer deal with error when
          * sense message is present.
          */
         if (vm_srb->srb_status & SRB_STATUS_AUTOSENSE_VALID)
             return;
 
         /*
          * If there is an error; offline the device since all
          * error recovery strategies would have already been
          * deployed on the host side. However, if the command
          * were a pass-through command deal with it appropriately.
          */
         switch (scmnd->cmnd[0]) {
         case ATA_16:
         case ATA_12:
             set_host_byte(scmnd, DID_PASSTHROUGH);
             break;
         /*
          * On some Hyper-V hosts TEST_UNIT_READY command can
          * return SRB_STATUS_ERROR. Let the upper level code
          * deal with it based on the sense information.
          */
         case TEST_UNIT_READY:
             break;
         default:
             set_host_byte(scmnd, DID_ERROR);
         }
     }
     return;
 
 do_work:
     /*
      * We need to schedule work to process this error; schedule it.
      */
     wrk = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
     if (!wrk) {
         set_host_byte(scmnd, DID_TARGET_FAILURE);
         return;
     }
 
     wrk->host = host;
     wrk->lun = vm_srb->lun;
     wrk->tgt_id = vm_srb->target_id;
     INIT_WORK(&wrk->work, process_err_fn);
     queue_work(host_dev->handle_error_wq, &wrk->work);
 }
 
 
 static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request,
                        struct storvsc_device *stor_dev)
 {
     struct scsi_cmnd *scmnd = cmd_request->cmd;
     struct scsi_sense_hdr sense_hdr;
     struct vmscsi_request *vm_srb;
     u32 data_transfer_length;
     struct Scsi_Host *host;
     u32 payload_sz = cmd_request->payload_sz;
     void *payload = cmd_request->payload;
     bool sense_ok;
 
     host = stor_dev->host;
 
     vm_srb = &cmd_request->vstor_packet.vm_srb;
     data_transfer_length = vm_srb->data_transfer_length;
 
     scmnd->result = vm_srb->scsi_status;
 
     if (scmnd->result) {
         sense_ok = scsi_normalize_sense(scmnd->sense_buffer,
                 SCSI_SENSE_BUFFERSIZE, &sense_hdr);
 
         if (sense_ok && do_logging(STORVSC_LOGGING_WARN))
             scsi_print_sense_hdr(scmnd->device, "storvsc",
                          &sense_hdr);
     }
 
     if (vm_srb->srb_status != SRB_STATUS_SUCCESS) {
         storvsc_handle_error(vm_srb, scmnd, host, sense_hdr.asc,
                      sense_hdr.ascq);
         /*
          * The Windows driver set data_transfer_length on
          * SRB_STATUS_DATA_OVERRUN. On other errors, this value
          * is untouched.  In these cases we set it to 0.
          */
         if (vm_srb->srb_status != SRB_STATUS_DATA_OVERRUN)
             data_transfer_length = 0;
     }
 
     /* Validate data_transfer_length (from Hyper-V) */
     if (data_transfer_length > cmd_request->payload->range.len)
         data_transfer_length = cmd_request->payload->range.len;
 
     scsi_set_resid(scmnd,
         cmd_request->payload->range.len - data_transfer_length);
 
     scsi_done(scmnd);
 
     if (payload_sz >
         sizeof(struct vmbus_channel_packet_multipage_buffer))
         kfree(payload);
 }
 
 static void storvsc_on_io_completion(struct storvsc_device *stor_device,
                   struct vstor_packet *vstor_packet,
                   struct storvsc_cmd_request *request)
 {
     struct vstor_packet *stor_pkt;
     struct hv_device *device = stor_device->device;
 
     stor_pkt = &request->vstor_packet;
 
     /*
      * The current SCSI handling on the host side does
      * not correctly handle:
      * INQUIRY command with page code parameter set to 0x80
      * MODE_SENSE command with cmd[2] == 0x1c
      *
      * Setup srb and scsi status so this won't be fatal.
      * We do this so we can distinguish truly fatal failues
      * (srb status == 0x4) and off-line the device in that case.
      */
 
     if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
        (stor_pkt->vm_srb.cdb[0] == MODE_SENSE)) {
         vstor_packet->vm_srb.scsi_status = 0;
         vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
     }
 
     /* Copy over the status...etc */
     stor_pkt->vm_srb.scsi_status = vstor_packet->vm_srb.scsi_status;
     stor_pkt->vm_srb.srb_status = vstor_packet->vm_srb.srb_status;
 
     /*
      * Copy over the sense_info_length, but limit to the known max
      * size if Hyper-V returns a bad value.
      */
     stor_pkt->vm_srb.sense_info_length = min_t(u8, STORVSC_SENSE_BUFFER_SIZE,
         vstor_packet->vm_srb.sense_info_length);
 
     if (vstor_packet->vm_srb.scsi_status != 0 ||
         vstor_packet->vm_srb.srb_status != SRB_STATUS_SUCCESS) {
 
         /*
          * Log TEST_UNIT_READY errors only as warnings. Hyper-V can
          * return errors when detecting devices using TEST_UNIT_READY,
          * and logging these as errors produces unhelpful noise.
          */
         int loglevel = (stor_pkt->vm_srb.cdb[0] == TEST_UNIT_READY) ?
             STORVSC_LOGGING_WARN : STORVSC_LOGGING_ERROR;
 
         storvsc_log(device, loglevel,
             "tag#%d cmd 0x%x status: scsi 0x%x srb 0x%x hv 0x%x\n",
             scsi_cmd_to_rq(request->cmd)->tag,
             stor_pkt->vm_srb.cdb[0],
             vstor_packet->vm_srb.scsi_status,
             vstor_packet->vm_srb.srb_status,
             vstor_packet->status);
     }
 
     if (vstor_packet->vm_srb.scsi_status == SAM_STAT_CHECK_CONDITION &&
         (vstor_packet->vm_srb.srb_status & SRB_STATUS_AUTOSENSE_VALID))
         memcpy(request->cmd->sense_buffer,
                vstor_packet->vm_srb.sense_data,
                stor_pkt->vm_srb.sense_info_length);
 
     stor_pkt->vm_srb.data_transfer_length =
         vstor_packet->vm_srb.data_transfer_length;
 
     storvsc_command_completion(request, stor_device);
 
     if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
         stor_device->drain_notify)
         wake_up(&stor_device->waiting_to_drain);
 }
 
 static void storvsc_on_receive(struct storvsc_device *stor_device,
                  struct vstor_packet *vstor_packet,
                  struct storvsc_cmd_request *request)
 {
     struct hv_host_device *host_dev;
     switch (vstor_packet->operation) {
     case VSTOR_OPERATION_COMPLETE_IO:
         storvsc_on_io_completion(stor_device, vstor_packet, request);
         break;
 
     case VSTOR_OPERATION_REMOVE_DEVICE:
     case VSTOR_OPERATION_ENUMERATE_BUS:
         host_dev = shost_priv(stor_device->host);
         queue_work(
             host_dev->handle_error_wq, &host_dev->host_scan_work);
         break;
 
     case VSTOR_OPERATION_FCHBA_DATA:
         cache_wwn(stor_device, vstor_packet);
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
         fc_host_node_name(stor_device->host) = stor_device->node_name;
         fc_host_port_name(stor_device->host) = stor_device->port_name;
 #endif
         break;
     default:
         break;
     }
 }
 
 static void storvsc_on_channel_callback(void *context)
 {
     struct vmbus_channel *channel = (struct vmbus_channel *)context;
     const struct vmpacket_descriptor *desc;
     struct hv_device *device;
     struct storvsc_device *stor_device;
     struct Scsi_Host *shost;
 
     if (channel->primary_channel != NULL)
         device = channel->primary_channel->device_obj;
     else
         device = channel->device_obj;
 
     stor_device = get_in_stor_device(device);
     if (!stor_device)
         return;
 
     shost = stor_device->host;
 
     foreach_vmbus_pkt(desc, channel) {
         struct vstor_packet *packet = hv_pkt_data(desc);
         struct storvsc_cmd_request *request = NULL;
         u32 pktlen = hv_pkt_datalen(desc);
         u64 rqst_id = desc->trans_id;
         u32 minlen = rqst_id ? sizeof(struct vstor_packet) :
             sizeof(enum vstor_packet_operation);
 
         if (pktlen < minlen) {
             dev_err(&device->device,
                 "Invalid pkt: id=%llu, len=%u, minlen=%u\n",
                 rqst_id, pktlen, minlen);
             continue;
         }
 
         if (rqst_id == VMBUS_RQST_INIT) {
             request = &stor_device->init_request;
         } else if (rqst_id == VMBUS_RQST_RESET) {
             request = &stor_device->reset_request;
         } else {
             /* Hyper-V can send an unsolicited message with ID of 0 */
             if (rqst_id == 0) {
                 /*
                  * storvsc_on_receive() looks at the vstor_packet in the message
                  * from the ring buffer.
                  *
                  * - If the operation in the vstor_packet is COMPLETE_IO, then
                  *   we call storvsc_on_io_completion(), and dereference the
                  *   guest memory address.  Make sure we don't call
                  *   storvsc_on_io_completion() with a guest memory address
                  *   that is zero if Hyper-V were to construct and send such
                  *   a bogus packet.
                  *
                  * - If the operation in the vstor_packet is FCHBA_DATA, then
                  *   we call cache_wwn(), and access the data payload area of
                  *   the packet (wwn_packet); however, there is no guarantee
                  *   that the packet is big enough to contain such area.
                  *   Future-proof the code by rejecting such a bogus packet.
                  */
                 if (packet->operation == VSTOR_OPERATION_COMPLETE_IO ||
                     packet->operation == VSTOR_OPERATION_FCHBA_DATA) {
                     dev_err(&device->device, "Invalid packet with ID of 0\n");
                     continue;
                 }
             } else {
                 struct scsi_cmnd *scmnd;
 
                 /* Transaction 'rqst_id' corresponds to tag 'rqst_id - 1' */
                 scmnd = scsi_host_find_tag(shost, rqst_id - 1);
                 if (scmnd == NULL) {
                     dev_err(&device->device, "Incorrect transaction ID\n");
                     continue;
                 }
                 request = (struct storvsc_cmd_request *)scsi_cmd_priv(scmnd);
                 scsi_dma_unmap(scmnd);
             }
 
             storvsc_on_receive(stor_device, packet, request);
             continue;
         }
 
         memcpy(&request->vstor_packet, packet,
                sizeof(struct vstor_packet));
         complete(&request->wait_event);
     }
 }
 
 static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
                   bool is_fc)
 {
     struct vmstorage_channel_properties props;
     int ret;
 
     memset(&props, 0, sizeof(struct vmstorage_channel_properties));
 
     device->channel->max_pkt_size = STORVSC_MAX_PKT_SIZE;
     device->channel->next_request_id_callback = storvsc_next_request_id;
 
     ret = vmbus_open(device->channel,
              ring_size,
              ring_size,
              (void *)&props,
              sizeof(struct vmstorage_channel_properties),
              storvsc_on_channel_callback, device->channel);
 
     if (ret != 0)
         return ret;
 
     ret = storvsc_channel_init(device, is_fc);
 
     return ret;
 }
 
 static int storvsc_dev_remove(struct hv_device *device)
 {
     struct storvsc_device *stor_device;
 
     stor_device = hv_get_drvdata(device);
 
     stor_device->destroy = true;
 
     /* Make sure flag is set before waiting */
     wmb();
 
     /*
      * At this point, all outbound traffic should be disable. We
      * only allow inbound traffic (responses) to proceed so that
      * outstanding requests can be completed.
      */
 
     storvsc_wait_to_drain(stor_device);
 
     /*
      * Since we have already drained, we don't need to busy wait
      * as was done in final_release_stor_device()
      * Note that we cannot set the ext pointer to NULL until
      * we have drained - to drain the outgoing packets, we need to
      * allow incoming packets.
      */
     hv_set_drvdata(device, NULL);
 
     /* Close the channel */
     vmbus_close(device->channel);
 
     kfree(stor_device->stor_chns);
     kfree(stor_device);
     return 0;
 }
 
 static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device,
                     u16 q_num)
 {
     u16 slot = 0;
     u16 hash_qnum;
     const struct cpumask *node_mask;
     int num_channels, tgt_cpu;
 
     if (stor_device->num_sc == 0) {
         stor_device->stor_chns[q_num] = stor_device->device->channel;
         return stor_device->device->channel;
     }
 
     /*
      * Our channel array is sparsley populated and we
      * initiated I/O on a processor/hw-q that does not
      * currently have a designated channel. Fix this.
      * The strategy is simple:
      * I. Ensure NUMA locality
      * II. Distribute evenly (best effort)
      */
 
     node_mask = cpumask_of_node(cpu_to_node(q_num));
 
     num_channels = 0;
     for_each_cpu(tgt_cpu, &stor_device->alloced_cpus) {
         if (cpumask_test_cpu(tgt_cpu, node_mask))
             num_channels++;
     }
     if (num_channels == 0) {
         stor_device->stor_chns[q_num] = stor_device->device->channel;
         return stor_device->device->channel;
     }
 
     hash_qnum = q_num;
     while (hash_qnum >= num_channels)
         hash_qnum -= num_channels;
 
     for_each_cpu(tgt_cpu, &stor_device->alloced_cpus) {
         if (!cpumask_test_cpu(tgt_cpu, node_mask))
             continue;
         if (slot == hash_qnum)
             break;
         slot++;
     }
 
     stor_device->stor_chns[q_num] = stor_device->stor_chns[tgt_cpu];
 
     return stor_device->stor_chns[q_num];
 }
 
 
 static int storvsc_do_io(struct hv_device *device,
              struct storvsc_cmd_request *request, u16 q_num)
 {
     struct storvsc_device *stor_device;
     struct vstor_packet *vstor_packet;
     struct vmbus_channel *outgoing_channel, *channel;
     unsigned long flags;
     int ret = 0;
     const struct cpumask *node_mask;
     int tgt_cpu;
 
     vstor_packet = &request->vstor_packet;
     stor_device = get_out_stor_device(device);
 
     if (!stor_device)
         return -ENODEV;
 
 
     request->device  = device;
     /*
      * Select an appropriate channel to send the request out.
      */
     /* See storvsc_change_target_cpu(). */
     outgoing_channel = READ_ONCE(stor_device->stor_chns[q_num]);
     if (outgoing_channel != NULL) {
         if (outgoing_channel->target_cpu == q_num) {
             /*
              * Ideally, we want to pick a different channel if
              * available on the same NUMA node.
              */
             node_mask = cpumask_of_node(cpu_to_node(q_num));
             for_each_cpu_wrap(tgt_cpu,
                  &stor_device->alloced_cpus, q_num + 1) {
                 if (!cpumask_test_cpu(tgt_cpu, node_mask))
                     continue;
                 if (tgt_cpu == q_num)
                     continue;
                 channel = READ_ONCE(
                     stor_device->stor_chns[tgt_cpu]);
                 if (channel == NULL)
                     continue;
                 if (hv_get_avail_to_write_percent(
                             &channel->outbound)
                         > ring_avail_percent_lowater) {
                     outgoing_channel = channel;
                     goto found_channel;
                 }
             }
 
             /*
              * All the other channels on the same NUMA node are
              * busy. Try to use the channel on the current CPU
              */
             if (hv_get_avail_to_write_percent(
                         &outgoing_channel->outbound)
                     > ring_avail_percent_lowater)
                 goto found_channel;
 
             /*
              * If we reach here, all the channels on the current
              * NUMA node are busy. Try to find a channel in
              * other NUMA nodes
              */
             for_each_cpu(tgt_cpu, &stor_device->alloced_cpus) {
                 if (cpumask_test_cpu(tgt_cpu, node_mask))
                     continue;
                 channel = READ_ONCE(
                     stor_device->stor_chns[tgt_cpu]);
                 if (channel == NULL)
                     continue;
                 if (hv_get_avail_to_write_percent(
                             &channel->outbound)
                         > ring_avail_percent_lowater) {
                     outgoing_channel = channel;
                     goto found_channel;
                 }
             }
         }
     } else {
         spin_lock_irqsave(&stor_device->lock, flags);
         outgoing_channel = stor_device->stor_chns[q_num];
         if (outgoing_channel != NULL) {
             spin_unlock_irqrestore(&stor_device->lock, flags);
             goto found_channel;
         }
         outgoing_channel = get_og_chn(stor_device, q_num);
         spin_unlock_irqrestore(&stor_device->lock, flags);
     }
 
 found_channel:
     vstor_packet->flags |= REQUEST_COMPLETION_FLAG;
 
     vstor_packet->vm_srb.length = sizeof(struct vmscsi_request);
 
 
     vstor_packet->vm_srb.sense_info_length = STORVSC_SENSE_BUFFER_SIZE;
 
 
     vstor_packet->vm_srb.data_transfer_length =
     request->payload->range.len;
 
     vstor_packet->operation = VSTOR_OPERATION_EXECUTE_SRB;
 
     if (request->payload->range.len) {
 
         ret = vmbus_sendpacket_mpb_desc(outgoing_channel,
                 request->payload, request->payload_sz,
                 vstor_packet,
                 sizeof(struct vstor_packet),
                 (unsigned long)request);
     } else {
         ret = vmbus_sendpacket(outgoing_channel, vstor_packet,
                    sizeof(struct vstor_packet),
                    (unsigned long)request,
                    VM_PKT_DATA_INBAND,
                    VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
     }
 
     if (ret != 0)
         return ret;
 
     atomic_inc(&stor_device->num_outstanding_req);
 
     return ret;
 }
 
 static int storvsc_device_alloc(struct scsi_device *sdevice)
 {
     /*
      * Set blist flag to permit the reading of the VPD pages even when
      * the target may claim SPC-2 compliance. MSFT targets currently
      * claim SPC-2 compliance while they implement post SPC-2 features.
      * With this flag we can correctly handle WRITE_SAME_16 issues.
      *
      * Hypervisor reports SCSI_UNKNOWN type for DVD ROM device but
      * still supports REPORT LUN.
      */
     sdevice->sdev_bflags = BLIST_REPORTLUN2 | BLIST_TRY_VPD_PAGES;
 
     return 0;
 }
 
 static int storvsc_device_configure(struct scsi_device *sdevice)
 {
     blk_queue_rq_timeout(sdevice->request_queue, (storvsc_timeout * HZ));
 
     sdevice->no_write_same = 1;
 
     /*
      * If the host is WIN8 or WIN8 R2, claim conformance to SPC-3
      * if the device is a MSFT virtual device.  If the host is
      * WIN10 or newer, allow write_same.
      */
     if (!strncmp(sdevice->vendor, "Msft", 4)) {
         switch (vmstor_proto_version) {
         case VMSTOR_PROTO_VERSION_WIN8:
         case VMSTOR_PROTO_VERSION_WIN8_1:
             sdevice->scsi_level = SCSI_SPC_3;
             break;
         }
 
         if (vmstor_proto_version >= VMSTOR_PROTO_VERSION_WIN10)
             sdevice->no_write_same = 0;
     }
 
     return 0;
 }
 
 static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev,
                sector_t capacity, int *info)
 {
     sector_t nsect = capacity;
     sector_t cylinders = nsect;
     int heads, sectors_pt;
 
     /*
      * We are making up these values; let us keep it simple.
      */
     heads = 0xff;
     sectors_pt = 0x3f;      /* Sectors per track */
     sector_div(cylinders, heads * sectors_pt);
     if ((sector_t)(cylinders + 1) * heads * sectors_pt < nsect)
         cylinders = 0xffff;
 
     info[0] = heads;
     info[1] = sectors_pt;
     info[2] = (int)cylinders;
 
     return 0;
 }
 
 static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
 {
     struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
     struct hv_device *device = host_dev->dev;
 
     struct storvsc_device *stor_device;
     struct storvsc_cmd_request *request;
     struct vstor_packet *vstor_packet;
     int ret, t;
 
     stor_device = get_out_stor_device(device);
     if (!stor_device)
         return FAILED;
 
     request = &stor_device->reset_request;
     vstor_packet = &request->vstor_packet;
     memset(vstor_packet, 0, sizeof(struct vstor_packet));
 
     init_completion(&request->wait_event);
 
     vstor_packet->operation = VSTOR_OPERATION_RESET_BUS;
     vstor_packet->flags = REQUEST_COMPLETION_FLAG;
     vstor_packet->vm_srb.path_id = stor_device->path_id;
 
     ret = vmbus_sendpacket(device->channel, vstor_packet,
                    sizeof(struct vstor_packet),
                    VMBUS_RQST_RESET,
                    VM_PKT_DATA_INBAND,
                    VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
     if (ret != 0)
         return FAILED;
 
     t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
     if (t == 0)
         return TIMEOUT_ERROR;
 
 
     /*
      * At this point, all outstanding requests in the adapter
      * should have been flushed out and return to us
      * There is a potential race here where the host may be in
      * the process of responding when we return from here.
      * Just wait for all in-transit packets to be accounted for
      * before we return from here.
      */
     storvsc_wait_to_drain(stor_device);
 
     return SUCCESS;
 }
 
 /*
  * The host guarantees to respond to each command, although I/O latencies might
  * be unbounded on Azure.  Reset the timer unconditionally to give the host a
  * chance to perform EH.
  */
 static enum blk_eh_timer_return storvsc_eh_timed_out(struct scsi_cmnd *scmnd)
 {
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     if (scmnd->device->host->transportt == fc_transport_template)
         return fc_eh_timed_out(scmnd);
 #endif
     return BLK_EH_RESET_TIMER;
 }
 
 static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
 {
     bool allowed = true;
     u8 scsi_op = scmnd->cmnd[0];
 
     switch (scsi_op) {
     /* the host does not handle WRITE_SAME, log accident usage */
     case WRITE_SAME:
     /*
      * smartd sends this command and the host does not handle
      * this. So, don't send it.
      */
     case SET_WINDOW:
         set_host_byte(scmnd, DID_ERROR);
         allowed = false;
         break;
     default:
         break;
     }
     return allowed;
 }
 
 static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 {
     int ret;
     struct hv_host_device *host_dev = shost_priv(host);
     struct hv_device *dev = host_dev->dev;
     struct storvsc_cmd_request *cmd_request = scsi_cmd_priv(scmnd);
     struct scatterlist *sgl;
     struct vmscsi_request *vm_srb;
     struct vmbus_packet_mpb_array  *payload;
     u32 payload_sz;
     u32 length;
 
     if (vmstor_proto_version <= VMSTOR_PROTO_VERSION_WIN8) {
         /*
          * On legacy hosts filter unimplemented commands.
          * Future hosts are expected to correctly handle
          * unsupported commands. Furthermore, it is
          * possible that some of the currently
          * unsupported commands maybe supported in
          * future versions of the host.
          */
         if (!storvsc_scsi_cmd_ok(scmnd)) {
             scsi_done(scmnd);
             return 0;
         }
     }
 
     /* Setup the cmd request */
     cmd_request->cmd = scmnd;
 
     memset(&cmd_request->vstor_packet, 0, sizeof(struct vstor_packet));
     vm_srb = &cmd_request->vstor_packet.vm_srb;
     vm_srb->time_out_value = 60;
 
     vm_srb->srb_flags |=
         SRB_FLAGS_DISABLE_SYNCH_TRANSFER;
 
     if (scmnd->device->tagged_supported) {
         vm_srb->srb_flags |=
         (SRB_FLAGS_QUEUE_ACTION_ENABLE | SRB_FLAGS_NO_QUEUE_FREEZE);
         vm_srb->queue_tag = SP_UNTAGGED;
         vm_srb->queue_action = SRB_SIMPLE_TAG_REQUEST;
     }
 
     /* Build the SRB */
     switch (scmnd->sc_data_direction) {
     case DMA_TO_DEVICE:
         vm_srb->data_in = WRITE_TYPE;
         vm_srb->srb_flags |= SRB_FLAGS_DATA_OUT;
         break;
     case DMA_FROM_DEVICE:
         vm_srb->data_in = READ_TYPE;
         vm_srb->srb_flags |= SRB_FLAGS_DATA_IN;
         break;
     case DMA_NONE:
         vm_srb->data_in = UNKNOWN_TYPE;
         vm_srb->srb_flags |= SRB_FLAGS_NO_DATA_TRANSFER;
         break;
     default:
         /*
          * This is DMA_BIDIRECTIONAL or something else we are never
          * supposed to see here.
          */
         WARN(1, "Unexpected data direction: %d\n",
              scmnd->sc_data_direction);
         return -EINVAL;
     }
 
 
     vm_srb->port_number = host_dev->port;
     vm_srb->path_id = scmnd->device->channel;
     vm_srb->target_id = scmnd->device->id;
     vm_srb->lun = scmnd->device->lun;
 
     vm_srb->cdb_length = scmnd->cmd_len;
 
     memcpy(vm_srb->cdb, scmnd->cmnd, vm_srb->cdb_length);
 
     sgl = (struct scatterlist *)scsi_sglist(scmnd);
 
     length = scsi_bufflen(scmnd);
     payload = (struct vmbus_packet_mpb_array *)&cmd_request->mpb;
     payload_sz = sizeof(cmd_request->mpb);
 
     if (scsi_sg_count(scmnd)) {
         unsigned long offset_in_hvpg = offset_in_hvpage(sgl->offset);
         unsigned int hvpg_count = HVPFN_UP(offset_in_hvpg + length);
         struct scatterlist *sg;
         unsigned long hvpfn, hvpfns_to_add;
         int j, i = 0, sg_count;
 
         if (hvpg_count > MAX_PAGE_BUFFER_COUNT) {
 
             payload_sz = (hvpg_count * sizeof(u64) +
                       sizeof(struct vmbus_packet_mpb_array));
             payload = kzalloc(payload_sz, GFP_ATOMIC);
             if (!payload)
                 return SCSI_MLQUEUE_DEVICE_BUSY;
         }
 
         payload->range.len = length;
         payload->range.offset = offset_in_hvpg;
 
         sg_count = scsi_dma_map(scmnd);
         if (sg_count < 0) {
             ret = SCSI_MLQUEUE_DEVICE_BUSY;
             goto err_free_payload;
         }
 
         for_each_sg(sgl, sg, sg_count, j) {
             /*
              * Init values for the current sgl entry. hvpfns_to_add
              * is in units of Hyper-V size pages. Handling the
              * PAGE_SIZE != HV_HYP_PAGE_SIZE case also handles
              * values of sgl->offset that are larger than PAGE_SIZE.
              * Such offsets are handled even on other than the first
              * sgl entry, provided they are a multiple of PAGE_SIZE.
              */
             hvpfn = HVPFN_DOWN(sg_dma_address(sg));
             hvpfns_to_add = HVPFN_UP(sg_dma_address(sg) +
                          sg_dma_len(sg)) - hvpfn;
 
             /*
              * Fill the next portion of the PFN array with
              * sequential Hyper-V PFNs for the continguous physical
              * memory described by the sgl entry. The end of the
              * last sgl should be reached at the same time that
              * the PFN array is filled.
              */
             while (hvpfns_to_add--)
                 payload->range.pfn_array[i++] = hvpfn++;
         }
     }
 
     cmd_request->payload = payload;
     cmd_request->payload_sz = payload_sz;
 
     /* Invokes the vsc to start an IO */
     ret = storvsc_do_io(dev, cmd_request, get_cpu());
     put_cpu();
 
     if (ret == -EAGAIN) {
         /* no more space */
         ret = SCSI_MLQUEUE_DEVICE_BUSY;
         goto err_free_payload;
     }
 
     return 0;
 
 err_free_payload:
     if (payload_sz > sizeof(cmd_request->mpb))
         kfree(payload);
 
     return ret;
 }
 
 static struct scsi_host_template scsi_driver = {
     .module =       THIS_MODULE,
     .name =         "storvsc_host_t",
     .cmd_size =             sizeof(struct storvsc_cmd_request),
     .bios_param =       storvsc_get_chs,
     .queuecommand =     storvsc_queuecommand,
     .eh_host_reset_handler =    storvsc_host_reset_handler,
     .proc_name =        "storvsc_host",
     .eh_timed_out =     storvsc_eh_timed_out,
     .slave_alloc =      storvsc_device_alloc,
     .slave_configure =  storvsc_device_configure,
     .cmd_per_lun =      2048,
     .this_id =      -1,
     /* Ensure there are no gaps in presented sgls */
     .virt_boundary_mask =   HV_HYP_PAGE_SIZE - 1,
     .no_write_same =    1,
     .track_queue_depth =    1,
     .change_queue_depth =   storvsc_change_queue_depth,
 };
 
 enum {
     SCSI_GUID,
     IDE_GUID,
     SFC_GUID,
 };
 
 static const struct hv_vmbus_device_id id_table[] = {
     /* SCSI guid */
     { HV_SCSI_GUID,
       .driver_data = SCSI_GUID
     },
     /* IDE guid */
     { HV_IDE_GUID,
       .driver_data = IDE_GUID
     },
     /* Fibre Channel GUID */
     {
       HV_SYNTHFC_GUID,
       .driver_data = SFC_GUID
     },
     { },
 };
 
 MODULE_DEVICE_TABLE(vmbus, id_table);
 
 static const struct { guid_t guid; } fc_guid = { HV_SYNTHFC_GUID };
 
 static bool hv_dev_is_fc(struct hv_device *hv_dev)
 {
     return guid_equal(&fc_guid.guid, &hv_dev->dev_type);
 }
 
 static int storvsc_probe(struct hv_device *device,
             const struct hv_vmbus_device_id *dev_id)
 {
     int ret;
     int num_cpus = num_online_cpus();
     int num_present_cpus = num_present_cpus();
     struct Scsi_Host *host;
     struct hv_host_device *host_dev;
     bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
     bool is_fc = ((dev_id->driver_data == SFC_GUID) ? true : false);
     int target = 0;
     struct storvsc_device *stor_device;
     int max_sub_channels = 0;
     u32 max_xfer_bytes;
 
     /*
      * We support sub-channels for storage on SCSI and FC controllers.
      * The number of sub-channels offerred is based on the number of
      * VCPUs in the guest.
      */
     if (!dev_is_ide)
         max_sub_channels =
             (num_cpus - 1) / storvsc_vcpus_per_sub_channel;
 
     scsi_driver.can_queue = max_outstanding_req_per_channel *
                 (max_sub_channels + 1) *
                 (100 - ring_avail_percent_lowater) / 100;
 
     host = scsi_host_alloc(&scsi_driver,
                    sizeof(struct hv_host_device));
     if (!host)
         return -ENOMEM;
 
     host_dev = shost_priv(host);
     memset(host_dev, 0, sizeof(struct hv_host_device));
 
     host_dev->port = host->host_no;
     host_dev->dev = device;
     host_dev->host = host;
 
 
     stor_device = kzalloc(sizeof(struct storvsc_device), GFP_KERNEL);
     if (!stor_device) {
         ret = -ENOMEM;
         goto err_out0;
     }
 
     stor_device->destroy = false;
     init_waitqueue_head(&stor_device->waiting_to_drain);
     stor_device->device = device;
     stor_device->host = host;
     spin_lock_init(&stor_device->lock);
     hv_set_drvdata(device, stor_device);
     dma_set_min_align_mask(&device->device, HV_HYP_PAGE_SIZE - 1);
 
     stor_device->port_number = host->host_no;
     ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size, is_fc);
     if (ret)
         goto err_out1;
 
     host_dev->path = stor_device->path_id;
     host_dev->target = stor_device->target_id;
 
     switch (dev_id->driver_data) {
     case SFC_GUID:
         host->max_lun = STORVSC_FC_MAX_LUNS_PER_TARGET;
         host->max_id = STORVSC_FC_MAX_TARGETS;
         host->max_channel = STORVSC_FC_MAX_CHANNELS - 1;
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
         host->transportt = fc_transport_template;
 #endif
         break;
 
     case SCSI_GUID:
         host->max_lun = STORVSC_MAX_LUNS_PER_TARGET;
         host->max_id = STORVSC_MAX_TARGETS;
         host->max_channel = STORVSC_MAX_CHANNELS - 1;
         break;
 
     default:
         host->max_lun = STORVSC_IDE_MAX_LUNS_PER_TARGET;
         host->max_id = STORVSC_IDE_MAX_TARGETS;
         host->max_channel = STORVSC_IDE_MAX_CHANNELS - 1;
         break;
     }
     /* max cmd length */
     host->max_cmd_len = STORVSC_MAX_CMD_LEN;
     /*
      * Any reasonable Hyper-V configuration should provide
      * max_transfer_bytes value aligning to HV_HYP_PAGE_SIZE,
      * protecting it from any weird value.
      */
     max_xfer_bytes = round_down(stor_device->max_transfer_bytes, HV_HYP_PAGE_SIZE);
     /* max_hw_sectors_kb */
     host->max_sectors = max_xfer_bytes >> 9;
     /*
      * There are 2 requirements for Hyper-V storvsc sgl segments,
      * based on which the below calculation for max segments is
      * done:
      *
      * 1. Except for the first and last sgl segment, all sgl segments
      *    should be align to HV_HYP_PAGE_SIZE, that also means the
      *    maximum number of segments in a sgl can be calculated by
      *    dividing the total max transfer length by HV_HYP_PAGE_SIZE.
      *
      * 2. Except for the first and last, each entry in the SGL must
      *    have an offset that is a multiple of HV_HYP_PAGE_SIZE.
      */
     host->sg_tablesize = (max_xfer_bytes >> HV_HYP_PAGE_SHIFT) + 1;
     /*
      * For non-IDE disks, the host supports multiple channels.
      * Set the number of HW queues we are supporting.
      */
     if (!dev_is_ide) {
         if (storvsc_max_hw_queues > num_present_cpus) {
             storvsc_max_hw_queues = 0;
             storvsc_log(device, STORVSC_LOGGING_WARN,
                 "Resetting invalid storvsc_max_hw_queues value to default.\n");
         }
         if (storvsc_max_hw_queues)
             host->nr_hw_queues = storvsc_max_hw_queues;
         else
             host->nr_hw_queues = num_present_cpus;
     }
 
     /*
      * Set the error handler work queue.
      */
     host_dev->handle_error_wq =
             alloc_ordered_workqueue("storvsc_error_wq_%d",
                         0,
                         host->host_no);
     if (!host_dev->handle_error_wq) {
         ret = -ENOMEM;
         goto err_out2;
     }
     INIT_WORK(&host_dev->host_scan_work, storvsc_host_scan);
     /* Register the HBA and start the scsi bus scan */
     ret = scsi_add_host(host, &device->device);
     if (ret != 0)
         goto err_out3;
 
     if (!dev_is_ide) {
         scsi_scan_host(host);
     } else {
         target = (device->dev_instance.b[5] << 8 |
              device->dev_instance.b[4]);
         ret = scsi_add_device(host, 0, target, 0);
         if (ret)
             goto err_out4;
     }
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     if (host->transportt == fc_transport_template) {
         struct fc_rport_identifiers ids = {
             .roles = FC_PORT_ROLE_FCP_DUMMY_INITIATOR,
         };
 
         fc_host_node_name(host) = stor_device->node_name;
         fc_host_port_name(host) = stor_device->port_name;
         stor_device->rport = fc_remote_port_add(host, 0, &ids);
         if (!stor_device->rport) {
             ret = -ENOMEM;
             goto err_out4;
         }
     }
 #endif
     return 0;
 
 err_out4:
     scsi_remove_host(host);
 
 err_out3:
     destroy_workqueue(host_dev->handle_error_wq);
 
 err_out2:
     /*
      * Once we have connected with the host, we would need to
      * to invoke storvsc_dev_remove() to rollback this state and
      * this call also frees up the stor_device; hence the jump around
      * err_out1 label.
      */
     storvsc_dev_remove(device);
     goto err_out0;
 
 err_out1:
     kfree(stor_device->stor_chns);
     kfree(stor_device);
 
 err_out0:
     scsi_host_put(host);
     return ret;
 }
 
 /* Change a scsi target's queue depth */
 static int storvsc_change_queue_depth(struct scsi_device *sdev, int queue_depth)
 {
     if (queue_depth > scsi_driver.can_queue)
         queue_depth = scsi_driver.can_queue;
 
     return scsi_change_queue_depth(sdev, queue_depth);
 }
 
 static int storvsc_remove(struct hv_device *dev)
 {
     struct storvsc_device *stor_device = hv_get_drvdata(dev);
     struct Scsi_Host *host = stor_device->host;
     struct hv_host_device *host_dev = shost_priv(host);
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     if (host->transportt == fc_transport_template) {
         fc_remote_port_delete(stor_device->rport);
         fc_remove_host(host);
     }
 #endif
     destroy_workqueue(host_dev->handle_error_wq);
     scsi_remove_host(host);
     storvsc_dev_remove(dev);
     scsi_host_put(host);
 
     return 0;
 }
 
 static int storvsc_suspend(struct hv_device *hv_dev)
 {
     struct storvsc_device *stor_device = hv_get_drvdata(hv_dev);
     struct Scsi_Host *host = stor_device->host;
     struct hv_host_device *host_dev = shost_priv(host);
 
     storvsc_wait_to_drain(stor_device);
 
     drain_workqueue(host_dev->handle_error_wq);
 
     vmbus_close(hv_dev->channel);
 
     kfree(stor_device->stor_chns);
     stor_device->stor_chns = NULL;
 
     cpumask_clear(&stor_device->alloced_cpus);
 
     return 0;
 }
 
 static int storvsc_resume(struct hv_device *hv_dev)
 {
     int ret;
 
     ret = storvsc_connect_to_vsp(hv_dev, storvsc_ringbuffer_size,
                      hv_dev_is_fc(hv_dev));
     return ret;
 }
 
 static struct hv_driver storvsc_drv = {
     .name = KBUILD_MODNAME,
     .id_table = id_table,
     .probe = storvsc_probe,
     .remove = storvsc_remove,
     .suspend = storvsc_suspend,
     .resume = storvsc_resume,
     .driver = {
         .probe_type = PROBE_PREFER_ASYNCHRONOUS,
     },
 };
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
 static struct fc_function_template fc_transport_functions = {
     .show_host_node_name = 1,
     .show_host_port_name = 1,
 };
 #endif
 
 static int __init storvsc_drv_init(void)
 {
     int ret;
 
     /*
      * Divide the ring buffer data size (which is 1 page less
      * than the ring buffer size since that page is reserved for
      * the ring buffer indices) by the max request size (which is
      * vmbus_channel_packet_multipage_buffer + struct vstor_packet + u64)
      */
     max_outstanding_req_per_channel =
         ((storvsc_ringbuffer_size - PAGE_SIZE) /
         ALIGN(MAX_MULTIPAGE_BUFFER_PACKET +
         sizeof(struct vstor_packet) + sizeof(u64),
         sizeof(u64)));
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     fc_transport_template = fc_attach_transport(&fc_transport_functions);
     if (!fc_transport_template)
         return -ENODEV;
 #endif
 
     ret = vmbus_driver_register(&storvsc_drv);
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     if (ret)
         fc_release_transport(fc_transport_template);
 #endif
 
     return ret;
 }
 
 static void __exit storvsc_drv_exit(void)
 {
     vmbus_driver_unregister(&storvsc_drv);
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
     fc_release_transport(fc_transport_template);
 #endif
 }
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Microsoft Hyper-V virtual storage driver");
 module_init(storvsc_drv_init);
 module_exit(storvsc_drv_exit);

This page was automatically generated by the 2.1.0 LXR engine. The LXR team