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decnet: convert dndev_lock to spinlock

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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: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2009-11-11 07:40:36 +00:00 committed by David S. Miller
parent 41bdecf17e
commit e5c140a340
1 changed files with 12 additions and 7 deletions
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19
net/decnet/dn_dev.c
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@ -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 @@ rarok:
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);
}