Date:	Fri, 19 Dec 2008 13:42:35 +0100
From:	Oliver Neukum <oliver@...kum.org>
To:	Chris Snook <csnook@...hat.com>
Cc:	Denis Joseph Barrow <D.Barow@...ion.com>, schwidefsky@...ibm.com,
	strasse@...ibm.com, Paul Hardwick <P.Hardwick@...ion.com>,
	ajb@...eresystems.co.uk, "Greg Kroah-Hartman" <greg@...ah.com>,
	linux-usb@...r.kernel.org, netdev@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: another race in hso

Am Freitag, 19. Dezember 2008 13:26:34 schrieb Chris Snook:
> Denis Joseph Barrow wrote:
> > Get Martin Schwidefsky to look over it.
> > I hope he needs to write a 3g modem driver for linux on the z series anyway
> > so he may as well get used to the code.
> 
> I hope they come out with one soon, so I can get that ultraportable mainframe 
> I've been thinking about.

Chris,

can you test on hso hardware? I have something rough that fixes the
network race (breaking serial right now) and needs testing.

	Regards
		Oliver

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index cc75c8b..8e34c81 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -167,7 +167,6 @@ struct hso_net {
 	struct sk_buff *skb_tx_buf;
 
 	enum pkt_parse_state rx_parse_state;
-	spinlock_t net_lock;
 
 	unsigned short rx_buf_size;
 	unsigned short rx_buf_missing;
@@ -216,7 +215,6 @@ struct hso_serial {
 	/* from usb_serial_port */
 	struct tty_struct *tty;
 	int open_count;
-	spinlock_t serial_lock;
 
 	int (*write_data) (struct hso_serial *serial);
 	/* Hacks required to get flow control
@@ -238,10 +236,13 @@ struct hso_device {
 
 	u32 port_spec;
 
-	u8 is_active;
-	u8 usb_gone;
+	char is_active:1;
+	char is_suspended:1;
+	char is_elevated:1;
+	char usb_gone:1;
 	struct work_struct async_get_intf;
 	struct work_struct async_put_intf;
+	spinlock_t lock;
 
 	struct usb_device *usb;
 	struct usb_interface *interface;
@@ -642,7 +643,6 @@ static void log_usb_status(int status, const char *function)
 static int hso_net_open(struct net_device *net)
 {
 	struct hso_net *odev = netdev_priv(net);
-	unsigned long flags = 0;
 
 	if (!odev) {
 		dev_err(&net->dev, "No net device !\n");
@@ -652,11 +652,11 @@ static int hso_net_open(struct net_device *net)
 	odev->skb_tx_buf = NULL;
 
 	/* setup environment */
-	spin_lock_irqsave(&odev->net_lock, flags);
+	spin_lock_irq(&odev->parent->lock);
 	odev->rx_parse_state = WAIT_IP;
 	odev->rx_buf_size = 0;
 	odev->rx_buf_missing = sizeof(struct iphdr);
-	spin_unlock_irqrestore(&odev->net_lock, flags);
+	spin_unlock_irq(&odev->parent->lock);
 
 	/* We are up and running. */
 	set_bit(HSO_NET_RUNNING, &odev->flags);
@@ -708,7 +708,9 @@ static void write_bulk_callback(struct urb *urb)
 	if (status)
 		log_usb_status(status, __func__);
 
+	spin_lock(&odev->parent->lock);
 	hso_put_activity(odev->parent);
+	spin_unlock(&odev->parent->lock);
 
 	/* Tell the network interface we are ready for another frame */
 	netif_wake_queue(odev->net);
@@ -718,14 +720,26 @@ static void write_bulk_callback(struct urb *urb)
 static int hso_net_start_xmit(struct sk_buff *skb, struct net_device *net)
 {
 	struct hso_net *odev = netdev_priv(net);
-	int result;
+	struct hso_device *pdev = odev->parent;
+	int result = 0;
 
 	/* Tell the kernel, "No more frames 'til we are done with this one." */
 	netif_stop_queue(net);
-	if (hso_get_activity(odev->parent) == -EAGAIN) {
-		odev->skb_tx_buf = skb;
-		return 0;
+
+	usb_mark_last_busy(pdev->usb);
+	spin_lock(&pdev->lock);
+	if (!pdev->is_active) {
+		if (!pdev->is_suspended) {
+			pdev->is_active = 1;
+		} else {
+			odev->skb_tx_buf = skb;
+			hso_get_activity(pdev);
+			result = 1;
+		}
 	}
+	spin_unlock(&pdev->lock);
+	if (result)
+		return 0;
 
 	/* log if asked */
 	DUMP1(skb->data, skb->len);
@@ -735,8 +749,8 @@ static int hso_net_start_xmit(struct sk_buff *skb, struct net_device *net)
 
 	/* Fill in the URB for shipping it out. */
 	usb_fill_bulk_urb(odev->mux_bulk_tx_urb,
-			  odev->parent->usb,
-			  usb_sndbulkpipe(odev->parent->usb,
+			  pdev->usb,
+			  usb_sndbulkpipe(pdev->usb,
 					  odev->out_endp->
 					  bEndpointAddress & 0x7F),
 			  odev->mux_bulk_tx_buf, skb->len, write_bulk_callback,
@@ -748,7 +762,7 @@ static int hso_net_start_xmit(struct sk_buff *skb, struct net_device *net)
 	/* Send the URB on its merry way. */
 	result = usb_submit_urb(odev->mux_bulk_tx_urb, GFP_ATOMIC);
 	if (result) {
-		dev_warn(&odev->parent->interface->dev,
+		dev_warn(&pdev->interface->dev,
 			"failed mux_bulk_tx_urb %d", result);
 		net->stats.tx_errors++;
 		netif_start_queue(net);
@@ -976,11 +990,11 @@ static void read_bulk_callback(struct urb *urb)
 	if (urb->actual_length) {
 		/* Handle the IP stream, add header and push it onto network
 		 * stack if the packet is complete. */
-		spin_lock(&odev->net_lock);
+		spin_lock(&odev->parent->lock);
 		packetizeRx(odev, urb->transfer_buffer, urb->actual_length,
 			    (urb->transfer_buffer_length >
 			     urb->actual_length) ? 1 : 0);
-		spin_unlock(&odev->net_lock);
+		spin_unlock(&odev->parent->lock);
 	}
 
 	/* We are done with this URB, resubmit it. Prep the USB to wait for
@@ -1167,17 +1181,17 @@ static void hso_std_serial_read_bulk_callback(struct urb *urb)
 			}
 		}
 		/* Valid data, handle RX data */
-		spin_lock(&serial->serial_lock);
+		spin_lock(&serial->parent->lock);
 		serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 1;
 		put_rxbuf_data_and_resubmit_bulk_urb(serial);
-		spin_unlock(&serial->serial_lock);
+		spin_unlock(&serial->parent->lock);
 	} else if (status == -ENOENT || status == -ECONNRESET) {
 		/* Unlinked - check for throttled port. */
 		D2("Port %d, successfully unlinked urb", serial->minor);
-		spin_lock(&serial->serial_lock);
+		spin_lock(&serial->parent->lock);
 		serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 0;
 		hso_resubmit_rx_bulk_urb(serial, urb);
-		spin_unlock(&serial->serial_lock);
+		spin_unlock(&serial->parent->lock);
 	} else {
 		D2("Port %d, status = %d for read urb", serial->minor, status);
 		return;
@@ -1192,12 +1206,12 @@ void hso_unthrottle_tasklet(struct hso_serial *serial)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	if ((serial->parent->port_spec & HSO_INTF_MUX))
 		put_rxbuf_data_and_resubmit_ctrl_urb(serial);
 	else
 		put_rxbuf_data_and_resubmit_bulk_urb(serial);
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 }
 
 static	void hso_unthrottle(struct tty_struct *tty)
@@ -1322,7 +1336,7 @@ static int hso_serial_write(struct tty_struct *tty, const unsigned char *buf,
 		return -ENODEV;
 	}
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 
 	space = serial->tx_data_length - serial->tx_buffer_count;
 	tx_bytes = (count < space) ? count : space;
@@ -1334,7 +1348,7 @@ static int hso_serial_write(struct tty_struct *tty, const unsigned char *buf,
 	serial->tx_buffer_count += tx_bytes;
 
 out:
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 
 	hso_kick_transmit(serial);
 	/* done */
@@ -1348,9 +1362,9 @@ static int hso_serial_write_room(struct tty_struct *tty)
 	int room;
 	unsigned long flags;
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	room = serial->tx_data_length - serial->tx_buffer_count;
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 
 	/* return free room */
 	return room;
@@ -1367,12 +1381,12 @@ static void hso_serial_set_termios(struct tty_struct *tty, struct ktermios *old)
 		   tty->termios->c_cflag, old->c_cflag);
 
 	/* the actual setup */
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	if (serial->open_count)
 		_hso_serial_set_termios(tty, old);
 	else
 		tty->termios = old;
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 
 	/* done */
 	return;
@@ -1389,9 +1403,9 @@ static int hso_serial_chars_in_buffer(struct tty_struct *tty)
 	if (serial == NULL)
 		return 0;
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	chars = serial->tx_buffer_count;
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 
 	return chars;
 }
@@ -1408,10 +1422,10 @@ static int hso_serial_tiocmget(struct tty_struct *tty, struct file *file)
 		return -EINVAL;
 	}
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	value = ((serial->rts_state) ? TIOCM_RTS : 0) |
 	    ((serial->dtr_state) ? TIOCM_DTR : 0);
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 
 	return value;
 }
@@ -1431,7 +1445,7 @@ static int hso_serial_tiocmset(struct tty_struct *tty, struct file *file,
 	}
 	if_num = serial->parent->interface->altsetting->desc.bInterfaceNumber;
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	if (set & TIOCM_RTS)
 		serial->rts_state = 1;
 	if (set & TIOCM_DTR)
@@ -1447,7 +1461,7 @@ static int hso_serial_tiocmset(struct tty_struct *tty, struct file *file,
 	if (serial->rts_state)
 		val |= 0x02;
 
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 
 	return usb_control_msg(serial->parent->usb,
 			       usb_rcvctrlpipe(serial->parent->usb, 0), 0x22,
@@ -1462,7 +1476,7 @@ static void hso_kick_transmit(struct hso_serial *serial)
 	unsigned long flags;
 	int res;
 
-	spin_lock_irqsave(&serial->serial_lock, flags);
+	spin_lock_irqsave(&serial->parent->lock, flags);
 	if (!serial->tx_buffer_count)
 		goto out;
 
@@ -1487,7 +1501,7 @@ static void hso_kick_transmit(struct hso_serial *serial)
 			serial->tx_urb_used = 1;
 	}
 out:
-	spin_unlock_irqrestore(&serial->serial_lock, flags);
+	spin_unlock_irqrestore(&serial->parent->lock, flags);
 }
 
 /* make a request (for reading and writing data to muxed serial port) */
@@ -1607,7 +1621,7 @@ static void intr_callback(struct urb *urb)
 								   (1 << i));
 			if (serial != NULL) {
 				D1("Pending read interrupt on port %d\n", i);
-				spin_lock(&serial->serial_lock);
+				spin_lock(&serial->parent->lock);
 				if (serial->rx_state == RX_IDLE) {
 					/* Setup and send a ctrl req read on
 					 * port i */
@@ -1621,7 +1635,7 @@ static void intr_callback(struct urb *urb)
 					D1("Already pending a read on "
 					   "port %d\n", i);
 				}
-				spin_unlock(&serial->serial_lock);
+				spin_unlock(&serial->parent->lock);
 			}
 		}
 	}
@@ -1655,9 +1669,9 @@ static void hso_std_serial_write_bulk_callback(struct urb *urb)
 		return;
 	}
 
-	spin_lock(&serial->serial_lock);
+	spin_lock(&serial->parent->lock);
 	serial->tx_urb_used = 0;
-	spin_unlock(&serial->serial_lock);
+	spin_unlock(&serial->parent->lock);
 	if (status) {
 		log_usb_status(status, __func__);
 		return;
@@ -1706,9 +1720,9 @@ static void ctrl_callback(struct urb *urb)
 	if (!serial)
 		return;
 
-	spin_lock(&serial->serial_lock);
+	spin_lock(&serial->parent->lock);
 	serial->tx_urb_used = 0;
-	spin_unlock(&serial->serial_lock);
+	spin_unlock(&serial->parent->lock);
 	if (status) {
 		log_usb_status(status, __func__);
 		return;
@@ -1724,9 +1738,9 @@ static void ctrl_callback(struct urb *urb)
 	    (USB_DIR_IN | USB_TYPE_OPTION_VENDOR | USB_RECIP_INTERFACE)) {
 		/* response to a read command */
 		serial->rx_urb_filled[0] = 1;
-		spin_lock(&serial->serial_lock);
+		spin_lock(&serial->parent->lock);
 		put_rxbuf_data_and_resubmit_ctrl_urb(serial);
-		spin_unlock(&serial->serial_lock);
+		spin_unlock(&serial->parent->lock);
 	} else {
 		hso_put_activity(serial->parent);
 		if (serial->tty)
@@ -1999,7 +2013,7 @@ static int hso_serial_common_create(struct hso_serial *serial, int num_urbs,
 	/* fill in specific data for later use */
 	serial->minor = minor;
 	serial->magic = HSO_SERIAL_MAGIC;
-	spin_lock_init(&serial->serial_lock);
+	spin_lock_init(&serial->parent->lock);
 	serial->num_rx_urbs = num_urbs;
 
 	/* RX, allocate urb and initialize */
@@ -2140,9 +2154,6 @@ static void hso_net_init(struct net_device *net)
 	net->mtu = DEFAULT_MTU - 14;
 	net->tx_queue_len = 10;
 	SET_ETHTOOL_OPS(net, &ops);
-
-	/* and initialize the semaphore */
-	spin_lock_init(&hso_net->net_lock);
 }
 
 /* Adds a network device in the network device table */
@@ -2630,6 +2641,7 @@ static int hso_probe(struct usb_interface *interface,
 		goto exit;
 	}
 
+	spin_lock_init(&hso_dev->lock);
 	usb_driver_claim_interface(&hso_driver, interface, hso_dev);
 
 	/* save our data pointer in this device */
@@ -2669,38 +2681,36 @@ static void async_put_intf(struct work_struct *data)
 
 static int hso_get_activity(struct hso_device *hso_dev)
 {
-	if (hso_dev->usb->state == USB_STATE_SUSPENDED) {
-		if (!hso_dev->is_active) {
-			hso_dev->is_active = 1;
-			schedule_work(&hso_dev->async_get_intf);
-		}
+	if (!hso_dev->is_elevated) {
+		hso_dev->is_elevated = 1;
+		schedule_work(&hso_dev->async_get_intf);
 	}
-
-	if (hso_dev->usb->state != USB_STATE_CONFIGURED)
-		return -EAGAIN;
-
-	usb_mark_last_busy(hso_dev->usb);
-
 	return 0;
 }
 
 static int hso_put_activity(struct hso_device *hso_dev)
 {
-	if (hso_dev->usb->state != USB_STATE_SUSPENDED) {
-		if (hso_dev->is_active) {
-			hso_dev->is_active = 0;
-			schedule_work(&hso_dev->async_put_intf);
-			return -EAGAIN;
-		}
+	if (hso_dev->is_elevated) {
+		hso_dev->is_elevated = 0;
+		schedule_work(&hso_dev->async_put_intf);
 	}
-	hso_dev->is_active = 0;
 	return 0;
 }
 
 /* called by kernel when we need to suspend device */
 static int hso_suspend(struct usb_interface *iface, pm_message_t message)
 {
-	int i, result;
+	struct hso_device *pdev = usb_get_intfdata(iface);
+	int i, result = 0;
+
+	spin_lock_irq(&pdev->lock);
+	if (pdev->usb->auto_pm && pdev->is_active)
+		result = -EBUSY;
+	else
+		pdev->is_suspended = 1;
+	spin_unlock_irq(&pdev->lock);
+	if (result)
+		return result;
 
 	/* Stop all serial ports */
 	for (i = 0; i < HSO_SERIAL_TTY_MINORS; i++) {
@@ -2730,6 +2740,7 @@ static int hso_resume(struct usb_interface *iface)
 {
 	int i, result = 0;
 	struct hso_net *hso_net;
+	struct hso_device *pdev = usb_get_intfdata(iface);
 
 	/* Start all serial ports */
 	for (i = 0; i < HSO_SERIAL_TTY_MINORS; i++) {
@@ -2765,6 +2776,10 @@ static int hso_resume(struct usb_interface *iface)
 	}
 
 out:
+	spin_lock_irq(&pdev->lock);
+	pdev->is_suspended = 0;
+	spin_unlock_irq(&pdev->lock);
+
 	return result;
 }
 
--
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