1 files changed, 35 insertions, 199 deletions

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 5a5d2a95070e..41ee2984a0df 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -79,14 +79,6 @@ MODULE_DEVICE_TABLE(usb, id_table);
 #define DCR_INIT_VAL       0x0c	/* SLCTIN, nINIT */
 #define ECR_INIT_VAL       0x00	/* SPP mode */
 
-struct urbtracker {
-	struct mos7715_parport  *mos_parport;
-	struct list_head        urblist_entry;
-	struct kref             ref_count;
-	struct urb              *urb;
-	struct usb_ctrlrequest	*setup;
-};
-
 enum mos7715_pp_modes {
 	SPP = 0<<5,
 	PS2 = 1<<5,      /* moschip calls this 'NIBBLE' mode */
@@ -96,12 +88,9 @@ enum mos7715_pp_modes {
 struct mos7715_parport {
 	struct parport          *pp;	       /* back to containing struct */
 	struct kref             ref_count;     /* to instance of this struct */
-	struct list_head        deferred_urbs; /* list deferred async urbs */
-	struct list_head        active_urbs;   /* list async urbs in flight */
-	spinlock_t              listlock;      /* protects list access */
 	bool                    msg_pending;   /* usb sync call pending */
 	struct completion       syncmsg_compl; /* usb sync call completed */
-	struct tasklet_struct   urb_tasklet;   /* for sending deferred urbs */
+	struct work_struct      work;          /* restore deferred writes */
 	struct usb_serial       *serial;       /* back to containing struct */
 	__u8	                shadowECR;     /* parallel port regs... */
 	__u8	                shadowDCR;
@@ -265,174 +254,8 @@ static void destroy_mos_parport(struct kref *kref)
 	kfree(mos_parport);
 }
 
-static void destroy_urbtracker(struct kref *kref)
-{
-	struct urbtracker *urbtrack =
-		container_of(kref, struct urbtracker, ref_count);
-	struct mos7715_parport *mos_parport = urbtrack->mos_parport;
-
-	usb_free_urb(urbtrack->urb);
-	kfree(urbtrack->setup);
-	kfree(urbtrack);
-	kref_put(&mos_parport->ref_count, destroy_mos_parport);
-}
-
 /*
- * This runs as a tasklet when sending an urb in a non-blocking parallel
- * port callback had to be deferred because the disconnect mutex could not be
- * obtained at the time.
- */
-static void send_deferred_urbs(struct tasklet_struct *t)
-{
-	int ret_val;
-	unsigned long flags;
-	struct mos7715_parport *mos_parport = from_tasklet(mos_parport, t,
-							   urb_tasklet);
-	struct urbtracker *urbtrack, *tmp;
-	struct list_head *cursor, *next;
-	struct device *dev;
-
-	/* if release function ran, game over */
-	if (unlikely(mos_parport->serial == NULL))
-		return;
-
-	dev = &mos_parport->serial->dev->dev;
-
-	/* try again to get the mutex */
-	if (!mutex_trylock(&mos_parport->serial->disc_mutex)) {
-		dev_dbg(dev, "%s: rescheduling tasklet\n", __func__);
-		tasklet_schedule(&mos_parport->urb_tasklet);
-		return;
-	}
-
-	/* if device disconnected, game over */
-	if (unlikely(mos_parport->serial->disconnected)) {
-		mutex_unlock(&mos_parport->serial->disc_mutex);
-		return;
-	}
-
-	spin_lock_irqsave(&mos_parport->listlock, flags);
-	if (list_empty(&mos_parport->deferred_urbs)) {
-		spin_unlock_irqrestore(&mos_parport->listlock, flags);
-		mutex_unlock(&mos_parport->serial->disc_mutex);
-		dev_dbg(dev, "%s: deferred_urbs list empty\n", __func__);
-		return;
-	}
-
-	/* move contents of deferred_urbs list to active_urbs list and submit */
-	list_for_each_safe(cursor, next, &mos_parport->deferred_urbs)
-		list_move_tail(cursor, &mos_parport->active_urbs);
-	list_for_each_entry_safe(urbtrack, tmp, &mos_parport->active_urbs,
-			    urblist_entry) {
-		ret_val = usb_submit_urb(urbtrack->urb, GFP_ATOMIC);
-		dev_dbg(dev, "%s: urb submitted\n", __func__);
-		if (ret_val) {
-			dev_err(dev, "usb_submit_urb() failed: %d\n", ret_val);
-			list_del(&urbtrack->urblist_entry);
-			kref_put(&urbtrack->ref_count, destroy_urbtracker);
-		}
-	}
-	spin_unlock_irqrestore(&mos_parport->listlock, flags);
-	mutex_unlock(&mos_parport->serial->disc_mutex);
-}
-
-/* callback for parallel port control urbs submitted asynchronously */
-static void async_complete(struct urb *urb)
-{
-	struct urbtracker *urbtrack = urb->context;
-	int status = urb->status;
-	unsigned long flags;
-
-	if (unlikely(status))
-		dev_dbg(&urb->dev->dev, "%s - nonzero urb status received: %d\n", __func__, status);
-
-	/* remove the urbtracker from the active_urbs list */
-	spin_lock_irqsave(&urbtrack->mos_parport->listlock, flags);
-	list_del(&urbtrack->urblist_entry);
-	spin_unlock_irqrestore(&urbtrack->mos_parport->listlock, flags);
-	kref_put(&urbtrack->ref_count, destroy_urbtracker);
-}
-
-static int write_parport_reg_nonblock(struct mos7715_parport *mos_parport,
-				      enum mos_regs reg, __u8 data)
-{
-	struct urbtracker *urbtrack;
-	int ret_val;
-	unsigned long flags;
-	struct usb_serial *serial = mos_parport->serial;
-	struct usb_device *usbdev = serial->dev;
-
-	/* create and initialize the control urb and containing urbtracker */
-	urbtrack = kmalloc(sizeof(struct urbtracker), GFP_ATOMIC);
-	if (!urbtrack)
-		return -ENOMEM;
-
-	urbtrack->urb = usb_alloc_urb(0, GFP_ATOMIC);
-	if (!urbtrack->urb) {
-		kfree(urbtrack);
-		return -ENOMEM;
-	}
-	urbtrack->setup = kmalloc(sizeof(*urbtrack->setup), GFP_ATOMIC);
-	if (!urbtrack->setup) {
-		usb_free_urb(urbtrack->urb);
-		kfree(urbtrack);
-		return -ENOMEM;
-	}
-	urbtrack->setup->bRequestType = (__u8)0x40;
-	urbtrack->setup->bRequest = (__u8)0x0e;
-	urbtrack->setup->wValue = cpu_to_le16(get_reg_value(reg, dummy));
-	urbtrack->setup->wIndex = cpu_to_le16(get_reg_index(reg));
-	urbtrack->setup->wLength = 0;
-	usb_fill_control_urb(urbtrack->urb, usbdev,
-			     usb_sndctrlpipe(usbdev, 0),
-			     (unsigned char *)urbtrack->setup,
-			     NULL, 0, async_complete, urbtrack);
-	kref_get(&mos_parport->ref_count);
-	urbtrack->mos_parport = mos_parport;
-	kref_init(&urbtrack->ref_count);
-	INIT_LIST_HEAD(&urbtrack->urblist_entry);
-
-	/*
-	 * get the disconnect mutex, or add tracker to the deferred_urbs list
-	 * and schedule a tasklet to try again later
-	 */
-	if (!mutex_trylock(&serial->disc_mutex)) {
-		spin_lock_irqsave(&mos_parport->listlock, flags);
-		list_add_tail(&urbtrack->urblist_entry,
-			      &mos_parport->deferred_urbs);
-		spin_unlock_irqrestore(&mos_parport->listlock, flags);
-		tasklet_schedule(&mos_parport->urb_tasklet);
-		dev_dbg(&usbdev->dev, "tasklet scheduled\n");
-		return 0;
-	}
-
-	/* bail if device disconnected */
-	if (serial->disconnected) {
-		kref_put(&urbtrack->ref_count, destroy_urbtracker);
-		mutex_unlock(&serial->disc_mutex);
-		return -ENODEV;
-	}
-
-	/* add the tracker to the active_urbs list and submit */
-	spin_lock_irqsave(&mos_parport->listlock, flags);
-	list_add_tail(&urbtrack->urblist_entry, &mos_parport->active_urbs);
-	spin_unlock_irqrestore(&mos_parport->listlock, flags);
-	ret_val = usb_submit_urb(urbtrack->urb, GFP_ATOMIC);
-	mutex_unlock(&serial->disc_mutex);
-	if (ret_val) {
-		dev_err(&usbdev->dev,
-			"%s: submit_urb() failed: %d\n", __func__, ret_val);
-		spin_lock_irqsave(&mos_parport->listlock, flags);
-		list_del(&urbtrack->urblist_entry);
-		spin_unlock_irqrestore(&mos_parport->listlock, flags);
-		kref_put(&urbtrack->ref_count, destroy_urbtracker);
-		return ret_val;
-	}
-	return 0;
-}
-
-/*
- * This is the the common top part of all parallel port callback operations that
+ * This is the common top part of all parallel port callback operations that
  * send synchronous messages to the device.  This implements convoluted locking
  * that avoids two scenarios: (1) a port operation is called after usbserial
  * has called our release function, at which point struct mos7715_parport has
@@ -458,6 +281,10 @@ static int parport_prologue(struct parport *pp)
 	reinit_completion(&mos_parport->syncmsg_compl);
 	spin_unlock(&release_lock);
 
+	/* ensure writes from restore are submitted before new requests */
+	if (work_pending(&mos_parport->work))
+		flush_work(&mos_parport->work);
+
 	mutex_lock(&mos_parport->serial->disc_mutex);
 	if (mos_parport->serial->disconnected) {
 		/* device disconnected */
@@ -482,6 +309,26 @@ static inline void parport_epilogue(struct parport *pp)
 	complete(&mos_parport->syncmsg_compl);
 }
 
+static void deferred_restore_writes(struct work_struct *work)
+{
+	struct mos7715_parport *mos_parport;
+
+	mos_parport = container_of(work, struct mos7715_parport, work);
+
+	mutex_lock(&mos_parport->serial->disc_mutex);
+
+	/* if device disconnected, game over */
+	if (mos_parport->serial->disconnected)
+		goto done;
+
+	write_mos_reg(mos_parport->serial, dummy, MOS7720_DCR,
+		      mos_parport->shadowDCR);
+	write_mos_reg(mos_parport->serial, dummy, MOS7720_ECR,
+		      mos_parport->shadowECR);
+done:
+	mutex_unlock(&mos_parport->serial->disc_mutex);
+}
+
 static void parport_mos7715_write_data(struct parport *pp, unsigned char d)
 {
 	struct mos7715_parport *mos_parport = pp->private_data;
@@ -641,10 +488,8 @@ static void parport_mos7715_restore_state(struct parport *pp,
 	}
 	mos_parport->shadowDCR = s->u.pc.ctr;
 	mos_parport->shadowECR = s->u.pc.ecr;
-	write_parport_reg_nonblock(mos_parport, MOS7720_DCR,
-				   mos_parport->shadowDCR);
-	write_parport_reg_nonblock(mos_parport, MOS7720_ECR,
-				   mos_parport->shadowECR);
+
+	schedule_work(&mos_parport->work);
 	spin_unlock(&release_lock);
 }
 
@@ -714,12 +559,9 @@ static int mos7715_parport_init(struct usb_serial *serial)
 
 	mos_parport->msg_pending = false;
 	kref_init(&mos_parport->ref_count);
-	spin_lock_init(&mos_parport->listlock);
-	INIT_LIST_HEAD(&mos_parport->active_urbs);
-	INIT_LIST_HEAD(&mos_parport->deferred_urbs);
 	usb_set_serial_data(serial, mos_parport); /* hijack private pointer */
 	mos_parport->serial = serial;
-	tasklet_setup(&mos_parport->urb_tasklet, send_deferred_urbs);
+	INIT_WORK(&mos_parport->work, deferred_restore_writes);
 	init_completion(&mos_parport->syncmsg_compl);
 
 	/* cycle parallel port reset bit */
@@ -1869,8 +1711,6 @@ static void mos7720_release(struct usb_serial *serial)
 
 	if (le16_to_cpu(serial->dev->descriptor.idProduct)
 	    == MOSCHIP_DEVICE_ID_7715) {
-		struct urbtracker *urbtrack;
-		unsigned long flags;
 		struct mos7715_parport *mos_parport =
 			usb_get_serial_data(serial);
 
@@ -1883,21 +1723,17 @@ static void mos7720_release(struct usb_serial *serial)
 		if (mos_parport->msg_pending)
 			wait_for_completion_timeout(&mos_parport->syncmsg_compl,
 					    msecs_to_jiffies(MOS_WDR_TIMEOUT));
+		/*
+		 * If delayed work is currently scheduled, wait for it to
+		 * complete. This also implies barriers that ensure the
+		 * below serial clearing is not hoisted above the ->work.
+		 */
+		cancel_work_sync(&mos_parport->work);
 
 		parport_remove_port(mos_parport->pp);
 		usb_set_serial_data(serial, NULL);
 		mos_parport->serial = NULL;
 
-		/* if tasklet currently scheduled, wait for it to complete */
-		tasklet_kill(&mos_parport->urb_tasklet);
-
-		/* unlink any urbs sent by the tasklet  */
-		spin_lock_irqsave(&mos_parport->listlock, flags);
-		list_for_each_entry(urbtrack,
-				    &mos_parport->active_urbs,
-				    urblist_entry)
-			usb_unlink_urb(urbtrack->urb);
-		spin_unlock_irqrestore(&mos_parport->listlock, flags);
 		parport_del_port(mos_parport->pp);
 
 		kref_put(&mos_parport->ref_count, destroy_mos_parport);