Commit b307b389 authored by Dexuan Cui's avatar Dexuan Cui Committed by Sasha Levin
Browse files

Drivers: hv: vmbus: Suspend after cleaning up hv_sock and sub channels 



Before suspend, Linux must make sure all the hv_sock channels have been
properly cleaned up, because a hv_sock connection can not persist across
hibernation, and the user-space app must be properly notified of the
state change of the connection.

Before suspend, Linux also must make sure all the sub-channels have been
destroyed, i.e. the related channel structs of the sub-channels must be
properly removed, otherwise they would cause a conflict when the
sub-channels are recreated upon resume.

Add a counter to track such channels, and vmbus_bus_suspend() should wait
for the counter to drop to zero.

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 1f48dcf1

drivers/hv/channel_mgmt.c

+26 −0
Original line number Diff line number Diff line
@@ -545,6 +545,10 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel) 


	mutex_lock(&vmbus_connection.channel_mutex);



	/* Remember the channels that should be cleaned up upon suspend. */

	if (is_hvsock_channel(newchannel) || is_sub_channel(newchannel))

		atomic_inc(&vmbus_connection.nr_chan_close_on_suspend);



	/*

	 * Now that we have acquired the channel_mutex,

	 * we can release the potentially racing rescind thread.
@@ -944,6 +948,16 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr) 
	vmbus_process_offer(newchannel);

}



static void check_ready_for_suspend_event(void)

{

	/*

	 * If all the sub-channels or hv_sock channels have been cleaned up,

	 * then it's safe to suspend.

	 */

	if (atomic_dec_and_test(&vmbus_connection.nr_chan_close_on_suspend))

		complete(&vmbus_connection.ready_for_suspend_event);

}



/*

 * vmbus_onoffer_rescind - Rescind offer handler.

 *
@@ -954,6 +968,7 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
	struct vmbus_channel_rescind_offer *rescind;

	struct vmbus_channel *channel;

	struct device *dev;

	bool clean_up_chan_for_suspend;



	rescind = (struct vmbus_channel_rescind_offer *)hdr;
@@ -993,6 +1008,8 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
		return;

	}



	clean_up_chan_for_suspend = is_hvsock_channel(channel) ||

				    is_sub_channel(channel);

	/*

	 * Before setting channel->rescind in vmbus_rescind_cleanup(), we

	 * should make sure the channel callback is not running any more.
@@ -1018,6 +1035,10 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
	if (channel->device_obj) {

		if (channel->chn_rescind_callback) {

			channel->chn_rescind_callback(channel);



			if (clean_up_chan_for_suspend)

				check_ready_for_suspend_event();



			return;

		}

		/*
@@ -1050,6 +1071,11 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
		}

		mutex_unlock(&vmbus_connection.channel_mutex);

	}



	/* The "channel" may have been freed. Do not access it any longer. */



	if (clean_up_chan_for_suspend)

		check_ready_for_suspend_event();

}



void vmbus_hvsock_device_unregister(struct vmbus_channel *channel)

drivers/hv/connection.c

+3 −0
Original line number Diff line number Diff line
@@ -26,6 +26,9 @@ 
struct vmbus_connection vmbus_connection = {

	.conn_state		= DISCONNECTED,

	.next_gpadl_handle	= ATOMIC_INIT(0xE1E10),



	.ready_for_suspend_event= COMPLETION_INITIALIZER(

				  vmbus_connection.ready_for_suspend_event),

};

EXPORT_SYMBOL_GPL(vmbus_connection);

drivers/hv/hyperv_vmbus.h

+12 −0
Original line number Diff line number Diff line
@@ -260,6 +260,18 @@ struct vmbus_connection { 
	struct workqueue_struct *work_queue;

	struct workqueue_struct *handle_primary_chan_wq;

	struct workqueue_struct *handle_sub_chan_wq;



	/*

	 * The number of sub-channels and hv_sock channels that should be

	 * cleaned up upon suspend: sub-channels will be re-created upon

	 * resume, and hv_sock channels should not survive suspend.

	 */

	atomic_t nr_chan_close_on_suspend;

	/*

	 * vmbus_bus_suspend() waits for "nr_chan_close_on_suspend" to

	 * drop to zero.

	 */

	struct completion ready_for_suspend_event;

};

drivers/hv/vmbus_drv.c

+43 −1
Original line number Diff line number Diff line
@@ -2127,7 +2127,8 @@ static int vmbus_acpi_add(struct acpi_device *device) 


static int vmbus_bus_suspend(struct device *dev)

{

	struct vmbus_channel *channel;

	struct vmbus_channel *channel, *sc;

	unsigned long flags;



	while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {

		/*
@@ -2146,6 +2147,44 @@ static int vmbus_bus_suspend(struct device *dev) 
	}

	mutex_unlock(&vmbus_connection.channel_mutex);



	/*

	 * Wait until all the sub-channels and hv_sock channels have been

	 * cleaned up. Sub-channels should be destroyed upon suspend, otherwise

	 * they would conflict with the new sub-channels that will be created

	 * in the resume path. hv_sock channels should also be destroyed, but

	 * a hv_sock channel of an established hv_sock connection can not be

	 * really destroyed since it may still be referenced by the userspace

	 * application, so we just force the hv_sock channel to be rescinded

	 * by vmbus_force_channel_rescinded(), and the userspace application

	 * will thoroughly destroy the channel after hibernation.

	 *

	 * Note: the counter nr_chan_close_on_suspend may never go above 0 if

	 * the VM has no sub-channel and hv_sock channel, e.g. a 1-vCPU VM.

	 */

	if (atomic_read(&vmbus_connection.nr_chan_close_on_suspend) > 0)

		wait_for_completion(&vmbus_connection.ready_for_suspend_event);



	mutex_lock(&vmbus_connection.channel_mutex);



	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {

		if (is_hvsock_channel(channel)) {

			if (!channel->rescind) {

				pr_err("hv_sock channel not rescinded!\n");

				WARN_ON_ONCE(1);

			}

			continue;

		}



		spin_lock_irqsave(&channel->lock, flags);

		list_for_each_entry(sc, &channel->sc_list, sc_list) {

			pr_err("Sub-channel not deleted!\n");

			WARN_ON_ONCE(1);

		}

		spin_unlock_irqrestore(&channel->lock, flags);

	}



	mutex_unlock(&vmbus_connection.channel_mutex);



	vmbus_initiate_unload(false);



	vmbus_connection.conn_state = DISCONNECTED;
@@ -2186,6 +2225,9 @@ static int vmbus_bus_resume(struct device *dev) 


	vmbus_request_offers();



	/* Reset the event for the next suspend. */

	reinit_completion(&vmbus_connection.ready_for_suspend_event);



	return 0;

}