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Commit e8537bd2 authored by Bjørn Mork's avatar Bjørn Mork Committed by Greg Kroah-Hartman
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USB: cdc-wdm: use two mutexes to allow simultaneous read and write 



using a separate read and write mutex for locking is sufficient to make the
driver accept simultaneous read and write. This improves useability a lot.

Signed-off-by: default avatarBjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent c428b70c

drivers/usb/class/cdc-wdm.c

+31 −18
Original line number Diff line number Diff line
@@ -88,7 +88,8 @@ struct wdm_device { 
	int			count;

	dma_addr_t		shandle;

	dma_addr_t		ihandle;

	struct mutex		lock;

	struct mutex		wlock;

	struct mutex		rlock;

	wait_queue_head_t	wait;

	struct work_struct	rxwork;

	int			werr;
@@ -323,7 +324,7 @@ static ssize_t wdm_write 
	}



	/* concurrent writes and disconnect */

	r = mutex_lock_interruptible(&desc->lock);

	r = mutex_lock_interruptible(&desc->wlock);

	rv = -ERESTARTSYS;

	if (r) {

		kfree(buf);
@@ -386,7 +387,7 @@ static ssize_t wdm_write 
out:

	usb_autopm_put_interface(desc->intf);

outnp:

	mutex_unlock(&desc->lock);

	mutex_unlock(&desc->wlock);

outnl:

	return rv < 0 ? rv : count;

}
@@ -399,7 +400,7 @@ static ssize_t wdm_read 
	struct wdm_device *desc = file->private_data;





	rv = mutex_lock_interruptible(&desc->lock); /*concurrent reads */

	rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */

	if (rv < 0)

		return -ERESTARTSYS;
@@ -476,7 +477,7 @@ static ssize_t wdm_read 
	rv = cntr;



err:

	mutex_unlock(&desc->lock);

	mutex_unlock(&desc->rlock);

	return rv;

}
@@ -542,7 +543,8 @@ static int wdm_open(struct inode *inode, struct file *file) 
	}

	intf->needs_remote_wakeup = 1;



	mutex_lock(&desc->lock);

	/* using write lock to protect desc->count */

	mutex_lock(&desc->wlock);

	if (!desc->count++) {

		desc->werr = 0;

		desc->rerr = 0;
@@ -555,7 +557,7 @@ static int wdm_open(struct inode *inode, struct file *file) 
	} else {

		rv = 0;

	}

	mutex_unlock(&desc->lock);

	mutex_unlock(&desc->wlock);

	usb_autopm_put_interface(desc->intf);

out:

	mutex_unlock(&wdm_mutex);
@@ -567,9 +569,11 @@ static int wdm_release(struct inode *inode, struct file *file) 
	struct wdm_device *desc = file->private_data;



	mutex_lock(&wdm_mutex);

	mutex_lock(&desc->lock);



	/* using write lock to protect desc->count */

	mutex_lock(&desc->wlock);

	desc->count--;

	mutex_unlock(&desc->lock);

	mutex_unlock(&desc->wlock);



	if (!desc->count) {

		dev_dbg(&desc->intf->dev, "wdm_release: cleanup");
@@ -667,7 +671,8 @@ static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id) 
	desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);

	if (!desc)

		goto out;

	mutex_init(&desc->lock);

	mutex_init(&desc->rlock);

	mutex_init(&desc->wlock);

	spin_lock_init(&desc->iuspin);

	init_waitqueue_head(&desc->wait);

	desc->wMaxCommand = maxcom;
@@ -781,10 +786,12 @@ static void wdm_disconnect(struct usb_interface *intf) 
	/* to terminate pending flushes */

	clear_bit(WDM_IN_USE, &desc->flags);

	spin_unlock_irqrestore(&desc->iuspin, flags);

	mutex_lock(&desc->lock);

	mutex_lock(&desc->rlock);

	mutex_lock(&desc->wlock);

	kill_urbs(desc);

	cancel_work_sync(&desc->rxwork);

	mutex_unlock(&desc->lock);

	mutex_unlock(&desc->wlock);

	mutex_unlock(&desc->rlock);

	wake_up_all(&desc->wait);

	if (!desc->count)

		cleanup(desc);
@@ -800,8 +807,10 @@ static int wdm_suspend(struct usb_interface *intf, pm_message_t message) 
	dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);



	/* if this is an autosuspend the caller does the locking */

	if (!PMSG_IS_AUTO(message))

		mutex_lock(&desc->lock);

	if (!PMSG_IS_AUTO(message)) {

		mutex_lock(&desc->rlock);

		mutex_lock(&desc->wlock);

	}

	spin_lock_irq(&desc->iuspin);



	if (PMSG_IS_AUTO(message) &&
@@ -817,8 +826,10 @@ static int wdm_suspend(struct usb_interface *intf, pm_message_t message) 
		kill_urbs(desc);

		cancel_work_sync(&desc->rxwork);

	}

	if (!PMSG_IS_AUTO(message))

		mutex_unlock(&desc->lock);

	if (!PMSG_IS_AUTO(message)) {

		mutex_unlock(&desc->wlock);

		mutex_unlock(&desc->rlock);

	}



	return rv;

}
@@ -856,7 +867,8 @@ static int wdm_pre_reset(struct usb_interface *intf) 
{

	struct wdm_device *desc = usb_get_intfdata(intf);



	mutex_lock(&desc->lock);

	mutex_lock(&desc->rlock);

	mutex_lock(&desc->wlock);

	kill_urbs(desc);



	/*
@@ -878,7 +890,8 @@ static int wdm_post_reset(struct usb_interface *intf) 
	int rv;



	rv = recover_from_urb_loss(desc);

	mutex_unlock(&desc->lock);

	mutex_unlock(&desc->wlock);

	mutex_unlock(&desc->rlock);

	return 0;

}