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Commit e5c140a3 authored by stephen hemminger's avatar stephen hemminger Committed by David S. Miller
Browse files

decnet: convert dndev_lock to spinlock 



There is no reason for this lock to be reader/writer since
the reader only has lock held for a very brief period.
The overhead of read_lock is more expensive than spinlock.

Compile tested only, I am not a decnet user.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 41bdecf1

net/decnet/dn_dev.c

+12 −7
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ extern struct neigh_table dn_neigh_table; 
 */

__le16 decnet_address = 0;



static DEFINE_RWLOCK(dndev_lock);

static DEFINE_SPINLOCK(dndev_lock);

static struct net_device *decnet_default_device;

static BLOCKING_NOTIFIER_HEAD(dnaddr_chain);
@@ -557,7 +557,8 @@ int dn_dev_ioctl(unsigned int cmd, void __user *arg) 
struct net_device *dn_dev_get_default(void)

{

	struct net_device *dev;

	read_lock(&dndev_lock);



	spin_lock(&dndev_lock);

	dev = decnet_default_device;

	if (dev) {

		if (dev->dn_ptr)
@@ -565,7 +566,8 @@ struct net_device *dn_dev_get_default(void) 
		else

			dev = NULL;

	}

	read_unlock(&dndev_lock);

	spin_unlock(&dndev_lock);



	return dev;

}
@@ -575,13 +577,15 @@ int dn_dev_set_default(struct net_device *dev, int force) 
	int rv = -EBUSY;

	if (!dev->dn_ptr)

		return -ENODEV;

	write_lock(&dndev_lock);



	spin_lock(&dndev_lock);

	if (force || decnet_default_device == NULL) {

		old = decnet_default_device;

		decnet_default_device = dev;

		rv = 0;

	}

	write_unlock(&dndev_lock);

	spin_unlock(&dndev_lock);



	if (old)

		dev_put(old);

	return rv;
@@ -589,13 +593,14 @@ int dn_dev_set_default(struct net_device *dev, int force) 


static void dn_dev_check_default(struct net_device *dev)

{

	write_lock(&dndev_lock);

	spin_lock(&dndev_lock);

	if (dev == decnet_default_device) {

		decnet_default_device = NULL;

	} else {

		dev = NULL;

	}

	write_unlock(&dndev_lock);

	spin_unlock(&dndev_lock);



	if (dev)

		dev_put(dev);

}