Commit d43e2fe7 authored by Dexuan Cui's avatar Dexuan Cui Committed by Greg Kroah-Hartman
Browse files

hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind() 



Since the 2 fucntions can safely run in vmbus_connection.work_queue without
hang, we don't need to schedule new work items into the per-channel workqueue.

Actally we can even remove the per-channel workqueue now -- we'll do it
in the next patch.

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 652594c7

drivers/hv/channel_mgmt.c

+28 −129
Original line number Diff line number Diff line
@@ -23,7 +23,6 @@ 
#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/wait.h>

#include <linux/delay.h>

#include <linux/mm.h>

#include <linux/slab.h>

#include <linux/list.h>
@@ -33,11 +32,6 @@ 


#include "hyperv_vmbus.h"



struct vmbus_rescind_work {

	struct work_struct work;

	struct vmbus_channel *channel;

};



/**

 * vmbus_prep_negotiate_resp() - Create default response for Hyper-V Negotiate message

 * @icmsghdrp: Pointer to msg header structure
@@ -134,20 +128,6 @@ bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, 


EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);



static void vmbus_sc_creation_cb(struct work_struct *work)

{

	struct vmbus_channel *newchannel = container_of(work,

							struct vmbus_channel,

							work);

	struct vmbus_channel *primary_channel = newchannel->primary_channel;



	/*

	 * On entry sc_creation_callback has been already verified to

	 * be non-NULL.

	 */

	primary_channel->sc_creation_callback(newchannel);

}



/*

 * alloc_channel - Allocate and initialize a vmbus channel object

 */
@@ -206,40 +186,6 @@ static void free_channel(struct vmbus_channel *channel) 
	queue_work(vmbus_connection.work_queue, &channel->work);

}



static void process_rescind_fn(struct work_struct *work)

{

	struct vmbus_rescind_work *rc_work;

	struct vmbus_channel *channel;

	struct device *dev;



	rc_work = container_of(work, struct vmbus_rescind_work, work);

	channel = rc_work->channel;



	/*

	 * We have already acquired a reference on the channel

	 * and so it cannot vanish underneath us.

	 * It is possible (while very unlikely) that we may

	 * get here while the processing of the initial offer

	 * is still not complete. Deal with this situation by

	 * just waiting until the channel is in the correct state.

	 */



	while (channel->work.func != release_channel)

		msleep(1000);



	if (channel->device_obj) {

		dev = get_device(&channel->device_obj->device);

		if (dev) {

			vmbus_device_unregister(channel->device_obj);

			put_device(dev);

		}

	} else {

		hv_process_channel_removal(channel,

					   channel->offermsg.child_relid);

	}

	kfree(work);

}



static void percpu_channel_enq(void *arg)

{

	struct vmbus_channel *channel = arg;
@@ -302,46 +248,6 @@ void vmbus_free_channels(void) 
	}

}



static void vmbus_do_device_register(struct work_struct *work)

{

	struct hv_device *device_obj;

	int ret;

	unsigned long flags;

	struct vmbus_channel *newchannel = container_of(work,

						     struct vmbus_channel,

						     work);



	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);

		device_obj = newchannel->device_obj;

		newchannel->device_obj = NULL;

		spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);



		if (newchannel->target_cpu != get_cpu()) {

			put_cpu();

			smp_call_function_single(newchannel->target_cpu,

					 percpu_channel_deq, newchannel, true);

		} else {

			percpu_channel_deq(newchannel);

			put_cpu();

		}



		kfree(device_obj);

		if (!newchannel->rescind) {

			free_channel(newchannel);

			return;

		}

	}

	/*

	 * The next state for this channel is to be freed.

	 */

	INIT_WORK(&newchannel->work, release_channel);

}



/*

 * vmbus_process_offer - Process the offer by creating a channel/device

 * associated with this offer
@@ -410,19 +316,8 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel) 


			newchannel->state = CHANNEL_OPEN_STATE;

			channel->num_sc++;

			if (channel->sc_creation_callback != NULL) {

				/*

				 * We need to invoke the sub-channel creation

				 * callback; invoke this in a seperate work

				 * context since we are currently running on

				 * the global work context in which we handle

				 * messages from the host.

				 */

				INIT_WORK(&newchannel->work,

					  vmbus_sc_creation_cb);

				queue_work(newchannel->controlwq,

					   &newchannel->work);

			}

			if (channel->sc_creation_callback != NULL)

				channel->sc_creation_callback(newchannel);



			return;

		}
@@ -453,13 +348,13 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel) 
	 * Add the new device to the bus. This will kick off device-driver

	 * binding which eventually invokes the device driver's AddDevice()

	 * method.

	 * Invoke this call on the per-channel work context.

	 * Until we return from this function, rescind offer message

	 * cannot be processed as we are running on the global message

	 * handling work.

	 */

	INIT_WORK(&newchannel->work, vmbus_do_device_register);

	queue_work(newchannel->controlwq, &newchannel->work);

	if (vmbus_device_register(newchannel->device_obj) != 0) {

		pr_err("unable to add child device object (relid %d)\n",

			newchannel->offermsg.child_relid);

		kfree(newchannel->device_obj);

		goto err_deq_chan;

	}

	return;



err_deq_chan:
@@ -613,31 +508,35 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
{

	struct vmbus_channel_rescind_offer *rescind;

	struct vmbus_channel *channel;

	struct vmbus_rescind_work *rc_work;

	unsigned long flags;

	struct device *dev;



	rescind = (struct vmbus_channel_rescind_offer *)hdr;

	channel = relid2channel(rescind->child_relid, true);

	channel = relid2channel(rescind->child_relid);



	if (channel == NULL) {

		hv_process_channel_removal(NULL, rescind->child_relid);

		return;

	}



	spin_lock_irqsave(&channel->lock, flags);

	channel->rescind = true;

	spin_unlock_irqrestore(&channel->lock, flags);



	if (channel->device_obj) {

		/*

	 * We have acquired a reference on the channel and have posted

	 * the rescind state. Perform further cleanup in a work context

	 * that is different from the global work context in which

	 * we process messages from the host (we are currently executing

	 * on that global context.

		 * We will have to unregister this device from the

		 * driver core.

		 */

	rc_work = kzalloc(sizeof(struct vmbus_rescind_work), GFP_KERNEL);

	if (!rc_work) {

		pr_err("Unable to allocate memory for rescind processing ");

		return;

		dev = get_device(&channel->device_obj->device);

		if (dev) {

			vmbus_device_unregister(channel->device_obj);

			put_device(dev);

		}

	} else {

		hv_process_channel_removal(channel,

			channel->offermsg.child_relid);

	}

	rc_work->channel = channel;

	INIT_WORK(&rc_work->work, process_rescind_fn);

	schedule_work(&rc_work->work);

}



/*

drivers/hv/connection.c

+1 −5
Original line number Diff line number Diff line
@@ -270,7 +270,7 @@ static struct vmbus_channel *pcpu_relid2channel(u32 relid) 
 * relid2channel - Get the channel object given its

 * child relative id (ie channel id)

 */

struct vmbus_channel *relid2channel(u32 relid, bool rescind)

struct vmbus_channel *relid2channel(u32 relid)

{

	struct vmbus_channel *channel;

	struct vmbus_channel *found_channel  = NULL;
@@ -282,8 +282,6 @@ struct vmbus_channel *relid2channel(u32 relid, bool rescind) 
	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {

		if (channel->offermsg.child_relid == relid) {

			found_channel = channel;

			if (rescind)

				found_channel->rescind = true;

			break;

		} else if (!list_empty(&channel->sc_list)) {

			/*
@@ -294,8 +292,6 @@ struct vmbus_channel *relid2channel(u32 relid, bool rescind) 
							sc_list);

				if (cur_sc->offermsg.child_relid == relid) {

					found_channel = cur_sc;

					if (rescind)

						found_channel->rescind = true;

					break;

				}

			}

drivers/hv/hyperv_vmbus.h

+1 −1
Original line number Diff line number Diff line
@@ -715,7 +715,7 @@ void vmbus_device_unregister(struct hv_device *device_obj); 
/* VmbusChildDeviceDestroy( */

/* struct hv_device *); */



struct vmbus_channel *relid2channel(u32 relid, bool rescind);

struct vmbus_channel *relid2channel(u32 relid);



void vmbus_free_channels(void);