Commit 652594c7 authored by Dexuan Cui's avatar Dexuan Cui Committed by Greg Kroah-Hartman
Browse files

hv: run non-blocking message handlers in the dispatch tasklet 



A work item in vmbus_connection.work_queue can sleep, waiting for a new
host message (usually it is some kind of "completion" message). Currently
the new message will be handled in the same workqueue, but since work items
in the workqueue is serialized, we actually have no chance to handle
the new message if the current work item is sleeping -- as as result, the
current work item will hang forever.

K. Y. has posted the below fix to resolve the issue:
Drivers: hv: vmbus: Perform device register in the per-channel work element

Actually we can simplify the fix by directly running non-blocking message
handlers in the dispatch tasklet (inspired by K. Y.).

This patch is the fundamental change. The following 2 patches will simplify
the message offering and rescind-offering handling a lot.

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 01081f5a

drivers/hv/channel_mgmt.c

+18 −23
Original line number Diff line number Diff line
@@ -33,11 +33,6 @@ 


#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);

};



struct vmbus_rescind_work {

	struct work_struct work;

	struct vmbus_channel *channel;
@@ -827,25 +822,25 @@ static void vmbus_onversion_response( 
}



/* Channel message dispatch table */

static struct vmbus_channel_message_table_entry

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},

	{CHANNELMSG_INVALID,			0, NULL},

	{CHANNELMSG_OFFERCHANNEL,		0, vmbus_onoffer},

	{CHANNELMSG_RESCIND_CHANNELOFFER,	0, vmbus_onoffer_rescind},

	{CHANNELMSG_REQUESTOFFERS,		0, NULL},

	{CHANNELMSG_ALLOFFERS_DELIVERED,	1, vmbus_onoffers_delivered},

	{CHANNELMSG_OPENCHANNEL,		0, NULL},

	{CHANNELMSG_OPENCHANNEL_RESULT,		1, vmbus_onopen_result},

	{CHANNELMSG_CLOSECHANNEL,		0, NULL},

	{CHANNELMSG_GPADL_HEADER,		0, NULL},

	{CHANNELMSG_GPADL_BODY,			0, NULL},

	{CHANNELMSG_GPADL_CREATED,		1, vmbus_ongpadl_created},

	{CHANNELMSG_GPADL_TEARDOWN,		0, NULL},

	{CHANNELMSG_GPADL_TORNDOWN,		1, vmbus_ongpadl_torndown},

	{CHANNELMSG_RELID_RELEASED,		0, NULL},

	{CHANNELMSG_INITIATE_CONTACT,		0, NULL},

	{CHANNELMSG_VERSION_RESPONSE,		1, vmbus_onversion_response},

	{CHANNELMSG_UNLOAD,			0, NULL},

};



/*

drivers/hv/hyperv_vmbus.h

+17 −0
Original line number Diff line number Diff line
@@ -685,6 +685,23 @@ struct vmbus_msginfo { 


extern struct vmbus_connection vmbus_connection;



enum vmbus_message_handler_type {

	/* The related handler can sleep. */

	VMHT_BLOCKING = 0,



	/* The related handler must NOT sleep. */

	VMHT_NON_BLOCKING = 1,

};



struct vmbus_channel_message_table_entry {

	enum vmbus_channel_message_type message_type;

	enum vmbus_message_handler_type handler_type;

	void (*message_handler)(struct vmbus_channel_message_header *msg);

};



extern struct vmbus_channel_message_table_entry

	channel_message_table[CHANNELMSG_COUNT];



/* General vmbus interface */



struct hv_device *vmbus_device_create(const uuid_le *type,

drivers/hv/vmbus_drv.c

+18 −3
Original line number Diff line number Diff line
@@ -657,21 +657,36 @@ static void vmbus_on_msg_dpc(unsigned long data) 
	void *page_addr = hv_context.synic_message_page[cpu];

	struct hv_message *msg = (struct hv_message *)page_addr +

				  VMBUS_MESSAGE_SINT;

	struct vmbus_channel_message_header *hdr;

	struct vmbus_channel_message_table_entry *entry;

	struct onmessage_work_context *ctx;



	while (1) {

		if (msg->header.message_type == HVMSG_NONE) {

		if (msg->header.message_type == HVMSG_NONE)

			/* no msg */

			break;

		} else {



		hdr = (struct vmbus_channel_message_header *)msg->u.payload;



		if (hdr->msgtype >= CHANNELMSG_COUNT) {

			WARN_ONCE(1, "unknown msgtype=%d\n", hdr->msgtype);

			goto msg_handled;

		}



		entry = &channel_message_table[hdr->msgtype];

		if (entry->handler_type	== VMHT_BLOCKING) {

			ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);

			if (ctx == NULL)

				continue;



			INIT_WORK(&ctx->work, vmbus_onmessage_work);

			memcpy(&ctx->msg, msg, sizeof(*msg));



			queue_work(vmbus_connection.work_queue, &ctx->work);

		}

		} else

			entry->message_handler(hdr);



msg_handled:

		msg->header.message_type = HVMSG_NONE;



		/*

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