linux/drivers/hv/channel_mgmt.c
K. Y. Srinivasan e68d2971d2 Drivers: hv: vmbus: Implement multi-channel support
Starting with Win8, the host supports multiple sub-channels for a given
device. As in the past, the initial channel offer specifies the device and
is associated with both the type and the instance GUIDs. For performance
critical devices, the host may support multiple sub-channels. The sub-channels
share the same type and instance GUID as the primary channel. The number of
sub-channels offerrred to the guest depends on the number of virtual CPUs
assigned to the guest. The guest can request the creation of these sub-channels
and once created and opened, the guest can distribute the traffic across all
the channels (the primary and the sub-channels). A request sent on a sub-channel
will have the response delivered on the same sub-channel.

At channel (sub-channel) creation we bind the channel interrupt to a CPU and
with this sub-channel support we will be able to spread the interrupt load
of a given device across all available CPUs.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-06-03 14:09:14 -07:00

800 lines
22 KiB
C

/*
* Copyright (c) 2009, Microsoft Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
* Place - Suite 330, Boston, MA 02111-1307 USA.
*
* Authors:
* Haiyang Zhang <haiyangz@microsoft.com>
* Hank Janssen <hjanssen@microsoft.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/completion.h>
#include <linux/hyperv.h>
#include "hyperv_vmbus.h"
struct vmbus_channel_message_table_entry {
enum vmbus_channel_message_type message_type;
void (*message_handler)(struct vmbus_channel_message_header *msg);
};
/**
* vmbus_prep_negotiate_resp() - Create default response for Hyper-V Negotiate message
* @icmsghdrp: Pointer to msg header structure
* @icmsg_negotiate: Pointer to negotiate message structure
* @buf: Raw buffer channel data
*
* @icmsghdrp is of type &struct icmsg_hdr.
* @negop is of type &struct icmsg_negotiate.
* Set up and fill in default negotiate response message.
*
* The max_fw_version specifies the maximum framework version that
* we can support and max _srv_version specifies the maximum service
* version we can support. A special value MAX_SRV_VER can be
* specified to indicate that we can handle the maximum version
* exposed by the host.
*
* Mainly used by Hyper-V drivers.
*/
void vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
struct icmsg_negotiate *negop, u8 *buf,
int max_fw_version, int max_srv_version)
{
int icframe_vercnt;
int icmsg_vercnt;
int i;
icmsghdrp->icmsgsize = 0x10;
negop = (struct icmsg_negotiate *)&buf[
sizeof(struct vmbuspipe_hdr) +
sizeof(struct icmsg_hdr)];
icframe_vercnt = negop->icframe_vercnt;
icmsg_vercnt = negop->icmsg_vercnt;
/*
* Select the framework version number we will
* support.
*/
for (i = 0; i < negop->icframe_vercnt; i++) {
if (negop->icversion_data[i].major <= max_fw_version)
icframe_vercnt = negop->icversion_data[i].major;
}
for (i = negop->icframe_vercnt;
(i < negop->icframe_vercnt + negop->icmsg_vercnt); i++) {
if (negop->icversion_data[i].major <= max_srv_version)
icmsg_vercnt = negop->icversion_data[i].major;
}
/*
* Respond with the maximum framework and service
* version numbers we can support.
*/
negop->icframe_vercnt = 1;
negop->icmsg_vercnt = 1;
negop->icversion_data[0].major = icframe_vercnt;
negop->icversion_data[0].minor = 0;
negop->icversion_data[1].major = icmsg_vercnt;
negop->icversion_data[1].minor = 0;
}
EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
/*
* alloc_channel - Allocate and initialize a vmbus channel object
*/
static struct vmbus_channel *alloc_channel(void)
{
struct vmbus_channel *channel;
channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
if (!channel)
return NULL;
spin_lock_init(&channel->inbound_lock);
spin_lock_init(&channel->sc_lock);
INIT_LIST_HEAD(&channel->sc_list);
channel->controlwq = create_workqueue("hv_vmbus_ctl");
if (!channel->controlwq) {
kfree(channel);
return NULL;
}
return channel;
}
/*
* release_hannel - Release the vmbus channel object itself
*/
static void release_channel(struct work_struct *work)
{
struct vmbus_channel *channel = container_of(work,
struct vmbus_channel,
work);
destroy_workqueue(channel->controlwq);
kfree(channel);
}
/*
* free_channel - Release the resources used by the vmbus channel object
*/
static void free_channel(struct vmbus_channel *channel)
{
/*
* We have to release the channel's workqueue/thread in the vmbus's
* workqueue/thread context
* ie we can't destroy ourselves.
*/
INIT_WORK(&channel->work, release_channel);
queue_work(vmbus_connection.work_queue, &channel->work);
}
/*
* vmbus_process_rescind_offer -
* Rescind the offer by initiating a device removal
*/
static void vmbus_process_rescind_offer(struct work_struct *work)
{
struct vmbus_channel *channel = container_of(work,
struct vmbus_channel,
work);
unsigned long flags;
struct vmbus_channel *primary_channel;
struct vmbus_channel_relid_released msg;
vmbus_device_unregister(channel->device_obj);
memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
msg.child_relid = channel->offermsg.child_relid;
msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));
if (channel->primary_channel == NULL) {
spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
list_del(&channel->listentry);
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
} else {
primary_channel = channel->primary_channel;
spin_lock_irqsave(&primary_channel->sc_lock, flags);
list_del(&channel->listentry);
spin_unlock_irqrestore(&primary_channel->sc_lock, flags);
}
free_channel(channel);
}
void vmbus_free_channels(void)
{
struct vmbus_channel *channel;
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
vmbus_device_unregister(channel->device_obj);
kfree(channel->device_obj);
free_channel(channel);
}
}
/*
* vmbus_process_offer - Process the offer by creating a channel/device
* associated with this offer
*/
static void vmbus_process_offer(struct work_struct *work)
{
struct vmbus_channel *newchannel = container_of(work,
struct vmbus_channel,
work);
struct vmbus_channel *channel;
bool fnew = true;
int ret;
unsigned long flags;
/* The next possible work is rescind handling */
INIT_WORK(&newchannel->work, vmbus_process_rescind_offer);
/* Make sure this is a new offer */
spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
if (!uuid_le_cmp(channel->offermsg.offer.if_type,
newchannel->offermsg.offer.if_type) &&
!uuid_le_cmp(channel->offermsg.offer.if_instance,
newchannel->offermsg.offer.if_instance)) {
fnew = false;
break;
}
}
if (fnew)
list_add_tail(&newchannel->listentry,
&vmbus_connection.chn_list);
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
if (!fnew) {
/*
* Check to see if this is a sub-channel.
*/
if (newchannel->offermsg.offer.sub_channel_index != 0) {
/*
* Process the sub-channel.
*/
newchannel->primary_channel = channel;
spin_lock_irqsave(&channel->sc_lock, flags);
list_add_tail(&newchannel->sc_list, &channel->sc_list);
spin_unlock_irqrestore(&channel->sc_lock, flags);
newchannel->state = CHANNEL_OPEN_STATE;
if (channel->sc_creation_callback != NULL)
channel->sc_creation_callback(newchannel);
return;
}
free_channel(newchannel);
return;
}
/*
* Start the process of binding this offer to the driver
* We need to set the DeviceObject field before calling
* vmbus_child_dev_add()
*/
newchannel->device_obj = vmbus_device_create(
&newchannel->offermsg.offer.if_type,
&newchannel->offermsg.offer.if_instance,
newchannel);
/*
* Add the new device to the bus. This will kick off device-driver
* binding which eventually invokes the device driver's AddDevice()
* method.
*/
ret = vmbus_device_register(newchannel->device_obj);
if (ret != 0) {
pr_err("unable to add child device object (relid %d)\n",
newchannel->offermsg.child_relid);
spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
list_del(&newchannel->listentry);
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
kfree(newchannel->device_obj);
free_channel(newchannel);
} else {
/*
* This state is used to indicate a successful open
* so that when we do close the channel normally, we
* can cleanup properly
*/
newchannel->state = CHANNEL_OPEN_STATE;
}
}
enum {
IDE = 0,
SCSI,
NIC,
MAX_PERF_CHN,
};
/*
* This is an array of device_ids (device types) that are performance critical.
* We attempt to distribute the interrupt load for these devices across
* all available CPUs.
*/
static const struct hv_vmbus_device_id hp_devs[] = {
/* IDE */
{ HV_IDE_GUID, },
/* Storage - SCSI */
{ HV_SCSI_GUID, },
/* Network */
{ HV_NIC_GUID, },
};
/*
* We use this state to statically distribute the channel interrupt load.
*/
static u32 next_vp;
/*
* Starting with Win8, we can statically distribute the incoming
* channel interrupt load by binding a channel to VCPU. We
* implement here a simple round robin scheme for distributing
* the interrupt load.
* We will bind channels that are not performance critical to cpu 0 and
* performance critical channels (IDE, SCSI and Network) will be uniformly
* distributed across all available CPUs.
*/
static u32 get_vp_index(uuid_le *type_guid)
{
u32 cur_cpu;
int i;
bool perf_chn = false;
u32 max_cpus = num_online_cpus();
for (i = IDE; i < MAX_PERF_CHN; i++) {
if (!memcmp(type_guid->b, hp_devs[i].guid,
sizeof(uuid_le))) {
perf_chn = true;
break;
}
}
if ((vmbus_proto_version == VERSION_WS2008) ||
(vmbus_proto_version == VERSION_WIN7) || (!perf_chn)) {
/*
* Prior to win8, all channel interrupts are
* delivered on cpu 0.
* Also if the channel is not a performance critical
* channel, bind it to cpu 0.
*/
return 0;
}
cur_cpu = (++next_vp % max_cpus);
return hv_context.vp_index[cur_cpu];
}
/*
* vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
*
*/
static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_offer_channel *offer;
struct vmbus_channel *newchannel;
offer = (struct vmbus_channel_offer_channel *)hdr;
/* Allocate the channel object and save this offer. */
newchannel = alloc_channel();
if (!newchannel) {
pr_err("Unable to allocate channel object\n");
return;
}
/*
* By default we setup state to enable batched
* reading. A specific service can choose to
* disable this prior to opening the channel.
*/
newchannel->batched_reading = true;
/*
* Setup state for signalling the host.
*/
newchannel->sig_event = (struct hv_input_signal_event *)
(ALIGN((unsigned long)
&newchannel->sig_buf,
HV_HYPERCALL_PARAM_ALIGN));
newchannel->sig_event->connectionid.asu32 = 0;
newchannel->sig_event->connectionid.u.id = VMBUS_EVENT_CONNECTION_ID;
newchannel->sig_event->flag_number = 0;
newchannel->sig_event->rsvdz = 0;
if (vmbus_proto_version != VERSION_WS2008) {
newchannel->is_dedicated_interrupt =
(offer->is_dedicated_interrupt != 0);
newchannel->sig_event->connectionid.u.id =
offer->connection_id;
}
newchannel->target_vp = get_vp_index(&offer->offer.if_type);
memcpy(&newchannel->offermsg, offer,
sizeof(struct vmbus_channel_offer_channel));
newchannel->monitor_grp = (u8)offer->monitorid / 32;
newchannel->monitor_bit = (u8)offer->monitorid % 32;
INIT_WORK(&newchannel->work, vmbus_process_offer);
queue_work(newchannel->controlwq, &newchannel->work);
}
/*
* vmbus_onoffer_rescind - Rescind offer handler.
*
* We queue a work item to process this offer synchronously
*/
static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_rescind_offer *rescind;
struct vmbus_channel *channel;
rescind = (struct vmbus_channel_rescind_offer *)hdr;
channel = relid2channel(rescind->child_relid);
if (channel == NULL)
/* Just return here, no channel found */
return;
/* work is initialized for vmbus_process_rescind_offer() from
* vmbus_process_offer() where the channel got created */
queue_work(channel->controlwq, &channel->work);
}
/*
* vmbus_onoffers_delivered -
* This is invoked when all offers have been delivered.
*
* Nothing to do here.
*/
static void vmbus_onoffers_delivered(
struct vmbus_channel_message_header *hdr)
{
}
/*
* vmbus_onopen_result - Open result handler.
*
* This is invoked when we received a response to our channel open request.
* Find the matching request, copy the response and signal the requesting
* thread.
*/
static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_open_result *result;
struct vmbus_channel_msginfo *msginfo;
struct vmbus_channel_message_header *requestheader;
struct vmbus_channel_open_channel *openmsg;
unsigned long flags;
result = (struct vmbus_channel_open_result *)hdr;
/*
* Find the open msg, copy the result and signal/unblock the wait event
*/
spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
msglistentry) {
requestheader =
(struct vmbus_channel_message_header *)msginfo->msg;
if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
openmsg =
(struct vmbus_channel_open_channel *)msginfo->msg;
if (openmsg->child_relid == result->child_relid &&
openmsg->openid == result->openid) {
memcpy(&msginfo->response.open_result,
result,
sizeof(
struct vmbus_channel_open_result));
complete(&msginfo->waitevent);
break;
}
}
}
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
}
/*
* vmbus_ongpadl_created - GPADL created handler.
*
* This is invoked when we received a response to our gpadl create request.
* Find the matching request, copy the response and signal the requesting
* thread.
*/
static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_gpadl_created *gpadlcreated;
struct vmbus_channel_msginfo *msginfo;
struct vmbus_channel_message_header *requestheader;
struct vmbus_channel_gpadl_header *gpadlheader;
unsigned long flags;
gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
/*
* Find the establish msg, copy the result and signal/unblock the wait
* event
*/
spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
msglistentry) {
requestheader =
(struct vmbus_channel_message_header *)msginfo->msg;
if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
gpadlheader =
(struct vmbus_channel_gpadl_header *)requestheader;
if ((gpadlcreated->child_relid ==
gpadlheader->child_relid) &&
(gpadlcreated->gpadl == gpadlheader->gpadl)) {
memcpy(&msginfo->response.gpadl_created,
gpadlcreated,
sizeof(
struct vmbus_channel_gpadl_created));
complete(&msginfo->waitevent);
break;
}
}
}
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
}
/*
* vmbus_ongpadl_torndown - GPADL torndown handler.
*
* This is invoked when we received a response to our gpadl teardown request.
* Find the matching request, copy the response and signal the requesting
* thread.
*/
static void vmbus_ongpadl_torndown(
struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_gpadl_torndown *gpadl_torndown;
struct vmbus_channel_msginfo *msginfo;
struct vmbus_channel_message_header *requestheader;
struct vmbus_channel_gpadl_teardown *gpadl_teardown;
unsigned long flags;
gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
/*
* Find the open msg, copy the result and signal/unblock the wait event
*/
spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
msglistentry) {
requestheader =
(struct vmbus_channel_message_header *)msginfo->msg;
if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
gpadl_teardown =
(struct vmbus_channel_gpadl_teardown *)requestheader;
if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
memcpy(&msginfo->response.gpadl_torndown,
gpadl_torndown,
sizeof(
struct vmbus_channel_gpadl_torndown));
complete(&msginfo->waitevent);
break;
}
}
}
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
}
/*
* vmbus_onversion_response - Version response handler
*
* This is invoked when we received a response to our initiate contact request.
* Find the matching request, copy the response and signal the requesting
* thread.
*/
static void vmbus_onversion_response(
struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_msginfo *msginfo;
struct vmbus_channel_message_header *requestheader;
struct vmbus_channel_version_response *version_response;
unsigned long flags;
version_response = (struct vmbus_channel_version_response *)hdr;
spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
msglistentry) {
requestheader =
(struct vmbus_channel_message_header *)msginfo->msg;
if (requestheader->msgtype ==
CHANNELMSG_INITIATE_CONTACT) {
memcpy(&msginfo->response.version_response,
version_response,
sizeof(struct vmbus_channel_version_response));
complete(&msginfo->waitevent);
}
}
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
}
/* Channel message dispatch table */
static struct vmbus_channel_message_table_entry
channel_message_table[CHANNELMSG_COUNT] = {
{CHANNELMSG_INVALID, NULL},
{CHANNELMSG_OFFERCHANNEL, vmbus_onoffer},
{CHANNELMSG_RESCIND_CHANNELOFFER, vmbus_onoffer_rescind},
{CHANNELMSG_REQUESTOFFERS, NULL},
{CHANNELMSG_ALLOFFERS_DELIVERED, vmbus_onoffers_delivered},
{CHANNELMSG_OPENCHANNEL, NULL},
{CHANNELMSG_OPENCHANNEL_RESULT, vmbus_onopen_result},
{CHANNELMSG_CLOSECHANNEL, NULL},
{CHANNELMSG_GPADL_HEADER, NULL},
{CHANNELMSG_GPADL_BODY, NULL},
{CHANNELMSG_GPADL_CREATED, vmbus_ongpadl_created},
{CHANNELMSG_GPADL_TEARDOWN, NULL},
{CHANNELMSG_GPADL_TORNDOWN, vmbus_ongpadl_torndown},
{CHANNELMSG_RELID_RELEASED, NULL},
{CHANNELMSG_INITIATE_CONTACT, NULL},
{CHANNELMSG_VERSION_RESPONSE, vmbus_onversion_response},
{CHANNELMSG_UNLOAD, NULL},
};
/*
* vmbus_onmessage - Handler for channel protocol messages.
*
* This is invoked in the vmbus worker thread context.
*/
void vmbus_onmessage(void *context)
{
struct hv_message *msg = context;
struct vmbus_channel_message_header *hdr;
int size;
hdr = (struct vmbus_channel_message_header *)msg->u.payload;
size = msg->header.payload_size;
if (hdr->msgtype >= CHANNELMSG_COUNT) {
pr_err("Received invalid channel message type %d size %d\n",
hdr->msgtype, size);
print_hex_dump_bytes("", DUMP_PREFIX_NONE,
(unsigned char *)msg->u.payload, size);
return;
}
if (channel_message_table[hdr->msgtype].message_handler)
channel_message_table[hdr->msgtype].message_handler(hdr);
else
pr_err("Unhandled channel message type %d\n", hdr->msgtype);
}
/*
* vmbus_request_offers - Send a request to get all our pending offers.
*/
int vmbus_request_offers(void)
{
struct vmbus_channel_message_header *msg;
struct vmbus_channel_msginfo *msginfo;
int ret, t;
msginfo = kmalloc(sizeof(*msginfo) +
sizeof(struct vmbus_channel_message_header),
GFP_KERNEL);
if (!msginfo)
return -ENOMEM;
init_completion(&msginfo->waitevent);
msg = (struct vmbus_channel_message_header *)msginfo->msg;
msg->msgtype = CHANNELMSG_REQUESTOFFERS;
ret = vmbus_post_msg(msg,
sizeof(struct vmbus_channel_message_header));
if (ret != 0) {
pr_err("Unable to request offers - %d\n", ret);
goto cleanup;
}
t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
if (t == 0) {
ret = -ETIMEDOUT;
goto cleanup;
}
cleanup:
kfree(msginfo);
return ret;
}
/*
* Retrieve the (sub) channel on which to send an outgoing request.
* When a primary channel has multiple sub-channels, we choose a
* channel whose VCPU binding is closest to the VCPU on which
* this call is being made.
*/
struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary)
{
struct list_head *cur, *tmp;
int cur_cpu = hv_context.vp_index[smp_processor_id()];
struct vmbus_channel *cur_channel;
struct vmbus_channel *outgoing_channel = primary;
int cpu_distance, new_cpu_distance;
if (list_empty(&primary->sc_list))
return outgoing_channel;
list_for_each_safe(cur, tmp, &primary->sc_list) {
cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
if (cur_channel->state != CHANNEL_OPENED_STATE)
continue;
if (cur_channel->target_vp == cur_cpu)
return cur_channel;
cpu_distance = ((outgoing_channel->target_vp > cur_cpu) ?
(outgoing_channel->target_vp - cur_cpu) :
(cur_cpu - outgoing_channel->target_vp));
new_cpu_distance = ((cur_channel->target_vp > cur_cpu) ?
(cur_channel->target_vp - cur_cpu) :
(cur_cpu - cur_channel->target_vp));
if (cpu_distance < new_cpu_distance)
continue;
outgoing_channel = cur_channel;
}
return outgoing_channel;
}
EXPORT_SYMBOL_GPL(vmbus_get_outgoing_channel);
static void invoke_sc_cb(struct vmbus_channel *primary_channel)
{
struct list_head *cur, *tmp;
struct vmbus_channel *cur_channel;
if (primary_channel->sc_creation_callback == NULL)
return;
list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
primary_channel->sc_creation_callback(cur_channel);
}
}
void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
void (*sc_cr_cb)(struct vmbus_channel *new_sc))
{
primary_channel->sc_creation_callback = sc_cr_cb;
}
EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
{
bool ret;
ret = !list_empty(&primary->sc_list);
if (ret) {
/*
* Invoke the callback on sub-channel creation.
* This will present a uniform interface to the
* clients.
*/
invoke_sc_cb(primary);
}
return ret;
}
EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);