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Commit 4c93cccc authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
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Drivers: hv: fcopy: switch to using the hvutil_device_state state machine 



Switch to using the hvutil_device_state state machine from using 3 different state variables:
fcopy_transaction.active, opened, and in_hand_shake.

State transitions are:
-> HVUTIL_DEVICE_INIT when driver loads or on device release
-> HVUTIL_READY if the handshake was successful
-> HVUTIL_HOSTMSG_RECEIVED when there is a non-negotiation message from the host
-> HVUTIL_USERSPACE_REQ after userspace daemon read the message
   -> HVUTIL_USERSPACE_RECV after/if userspace has replied
-> HVUTIL_READY after we respond to the host
-> HVUTIL_DEVICE_DYING on driver unload

In hv_fcopy_onchannelcallback() process ICMSGTYPE_NEGOTIATE messages even when
the userspace daemon is disconnected, otherwise we can make the host think
we don't support FCOPY and disable the service completely.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: default avatarAlex Ng <alexng@microsoft.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 086a6f68

drivers/hv/hv_fcopy.c

+30 −40
Original line number Diff line number Diff line
@@ -47,15 +47,10 @@ 
 * ensure this by serializing packet processing in this driver - we do not

 * read additional packets from the VMBUs until the current packet is fully

 * handled.

 *

 * The transaction "active" state is set when we receive a request from the

 * host and we cleanup this state when the transaction is completed - when we

 * respond to the host with our response. When the transaction active state is

 * set, we defer handling incoming packets.

 */



static struct {

	bool active; /* transaction status - active or not */

	int state;   /* hvutil_device_state */

	int recv_len; /* number of bytes received. */

	struct hv_fcopy_hdr  *fcopy_msg; /* current message */

	struct hv_start_fcopy  message; /*  sent to daemon */
@@ -65,14 +60,6 @@ static struct { 
	struct semaphore read_sema;

} fcopy_transaction;



static bool opened; /* currently device opened */



/*

 * Before we can accept copy messages from the host, we need

 * to handshake with the user level daemon. This state tracks

 * if we are in the handshake phase.

 */

static bool in_hand_shake = true;

static void fcopy_send_data(void);

static void fcopy_respond_to_host(int error);

static void fcopy_timeout_func(struct work_struct *dummy);
@@ -87,6 +74,10 @@ static void fcopy_timeout_func(struct work_struct *dummy) 
	 */

	fcopy_respond_to_host(HV_E_FAIL);



	/* Transaction is finished, reset the state. */

	if (fcopy_transaction.state > HVUTIL_READY)

		fcopy_transaction.state = HVUTIL_READY;



	/* In the case the user-space daemon crashes, hangs or is killed, we

	 * need to down the semaphore, otherwise, after the daemon starts next

	 * time, the obsolete data in fcopy_transaction.message or
@@ -118,10 +109,9 @@ static int fcopy_handle_handshake(u32 version) 
	}

	pr_info("FCP: user-mode registering done. Daemon version: %d\n",

		version);

	fcopy_transaction.active = false;

	fcopy_transaction.state = HVUTIL_READY;

	hv_poll_channel(fcopy_transaction.fcopy_context,

			hv_fcopy_onchannelcallback);

	in_hand_shake = false;

	return 0;

}
@@ -191,8 +181,6 @@ fcopy_respond_to_host(int error) 
	channel = fcopy_transaction.recv_channel;

	req_id = fcopy_transaction.recv_req_id;



	fcopy_transaction.active = false;



	icmsghdr = (struct icmsg_hdr *)

			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
@@ -220,7 +208,7 @@ void hv_fcopy_onchannelcallback(void *context) 
	int util_fw_version;

	int fcopy_srv_version;



	if (fcopy_transaction.active) {

	if (fcopy_transaction.state > HVUTIL_READY) {

		/*

		 * We will defer processing this callback once

		 * the current transaction is complete.
@@ -252,12 +240,18 @@ void hv_fcopy_onchannelcallback(void *context) 
		 * transaction; note transactions are serialized.

		 */



		fcopy_transaction.active = true;

		fcopy_transaction.recv_len = recvlen;

		fcopy_transaction.recv_channel = channel;

		fcopy_transaction.recv_req_id = requestid;

		fcopy_transaction.fcopy_msg = fcopy_msg;



		if (fcopy_transaction.state < HVUTIL_READY) {

			/* Userspace is not registered yet */

			fcopy_respond_to_host(HV_E_FAIL);

			return;

		}

		fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;



		/*

		 * Send the information to the user-level daemon.

		 */
@@ -290,10 +284,10 @@ static ssize_t fcopy_read(struct file *file, char __user *buf, 


	/*

	 * The channel may be rescinded and in this case, we will wakeup the

	 * the thread blocked on the semaphore and we will use the opened

	 * state to correctly handle this case.

	 * the thread blocked on the semaphore and we will use the state to

	 * correctly handle this case.

	 */

	if (!opened)

	if (fcopy_transaction.state != HVUTIL_HOSTMSG_RECEIVED)

		return -ENODEV;



	operation = fcopy_transaction.fcopy_msg->operation;
@@ -312,6 +306,8 @@ static ssize_t fcopy_read(struct file *file, char __user *buf, 
	if (copy_to_user(buf, src, copy_size))

		return -EFAULT;



	fcopy_transaction.state = HVUTIL_USERSPACE_REQ;



	return copy_size;

}
@@ -326,18 +322,23 @@ static ssize_t fcopy_write(struct file *file, const char __user *buf, 
	if (copy_from_user(&response, buf, sizeof(int)))

		return -EFAULT;



	if (in_hand_shake) {

	if (fcopy_transaction.state == HVUTIL_DEVICE_INIT) {

		if (fcopy_handle_handshake(response))

			return -EINVAL;

		return sizeof(int);

	}



	if (fcopy_transaction.state != HVUTIL_USERSPACE_REQ)

		return -EINVAL;



	/*

	 * Complete the transaction by forwarding the result

	 * to the host. But first, cancel the timeout.

	 */

	if (cancel_delayed_work_sync(&fcopy_timeout_work))

	if (cancel_delayed_work_sync(&fcopy_timeout_work)) {

		fcopy_transaction.state = HVUTIL_USERSPACE_RECV;

		fcopy_respond_to_host(response);

		fcopy_transaction.state = HVUTIL_READY;

		hv_poll_channel(fcopy_transaction.fcopy_context,

				hv_fcopy_onchannelcallback);

	}
@@ -352,13 +353,9 @@ static int fcopy_open(struct inode *inode, struct file *f) 
	 * really an extension of this driver. We can have only

	 * active open at a time.

	 */

	if (opened)

	if (fcopy_transaction.state != HVUTIL_DEVICE_INIT)

		return -EBUSY;



	/*

	 * The daemon is alive; setup the state.

	 */

	opened = true;

	return 0;

}
@@ -375,8 +372,7 @@ static int fcopy_release(struct inode *inode, struct file *f) 
	/*

	 * The daemon has exited; reset the state.

	 */

	in_hand_shake = true;

	opened = false;

	fcopy_transaction.state = HVUTIL_DEVICE_INIT;



	if (cancel_delayed_work_sync(&fcopy_timeout_work)) {

		/* We haven't up()-ed the semaphore(very rare)? */
@@ -409,13 +405,6 @@ static int fcopy_dev_init(void) 
static void fcopy_dev_deinit(void)

{



	/*

	 * The device is going away - perhaps because the

	 * host has rescinded the channel. Setup state so that

	 * user level daemon can gracefully exit if it is blocked

	 * on the read semaphore.

	 */

	opened = false;

	/*

	 * Signal the semaphore as the device is

	 * going away.
@@ -434,7 +423,7 @@ int hv_fcopy_init(struct hv_util_service *srv) 
	 * Defer processing channel callbacks until the daemon

	 * has registered.

	 */

	fcopy_transaction.active = true;

	fcopy_transaction.state = HVUTIL_DEVICE_INIT;

	sema_init(&fcopy_transaction.read_sema, 0);



	return fcopy_dev_init();
@@ -442,6 +431,7 @@ int hv_fcopy_init(struct hv_util_service *srv) 


void hv_fcopy_deinit(void)

{

	fcopy_transaction.state = HVUTIL_DEVICE_DYING;

	cancel_delayed_work_sync(&fcopy_timeout_work);

	fcopy_dev_deinit();

}