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[NET]: Allow netdev REGISTER/CHANGENAME events to fail

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This patch adds code to allow errors to be passed up from event
handlers of NETDEV_REGISTER and NETDEV_CHANGENAME.  It also adds
the notifier_from_errno/notifier_to_errnor helpers to pass the
errno value up to the notifier caller.

If an error is detected when a device is registered, it causes
that operation to fail.  A NETDEV_UNREGISTER will be sent to
all event handlers.

Similarly if NETDEV_CHANGENAME fails the original name is restored
and a new NETDEV_CHANGENAME event is sent.

As such all event handlers must be idempotent with respect to
these events.

When an event handler is registered NETDEV_REGISTER events are
sent for all devices currently registered.  Should any of them
fail, we will send NETDEV_GOING_DOWN/NETDEV_DOWN/NETDEV_UNREGISTER
events to that handler for the devices which have already been
registered with it.  The handler registration itself will fail.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2007-07-30 17:03:38 -07:00 committed by David S. Miller
parent aeed9e82cd
commit fcc5a03ac4
2 changed files with 65 additions and 10 deletions
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13
include/linux/notifier.h
View file

@ -157,6 +157,19 @@ extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
*/
#define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK)
/* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */
static inline int notifier_from_errno(int err)
{
return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
}
/* Restore (negative) errno value from notify return value. */
static inline int notifier_to_errno(int ret)
{
ret &= ~NOTIFY_STOP_MASK;
return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0;
}
/*
* Declared notifiers so far. I can imagine quite a few more chains
* over time (eg laptop power reset chains, reboot chain (to clean

62
net/core/dev.c
View file

@ -817,7 +817,9 @@ int dev_alloc_name(struct net_device *dev, const char *name)
*/
int dev_change_name(struct net_device *dev, char *newname)
{
char oldname[IFNAMSIZ];
int err = 0;
int ret;
ASSERT_RTNL();
@ -827,6 +829,8 @@ int dev_change_name(struct net_device *dev, char *newname)
if (!dev_valid_name(newname))
return -EINVAL;
memcpy(oldname, dev->name, IFNAMSIZ);
if (strchr(newname, '%')) {
err = dev_alloc_name(dev, newname);
if (err < 0)
@ -838,6 +842,7 @@ int dev_change_name(struct net_device *dev, char *newname)
else
strlcpy(dev->name, newname, IFNAMSIZ);
rollback:
device_rename(&dev->dev, dev->name);
write_lock_bh(&dev_base_lock);
@ -845,7 +850,20 @@ int dev_change_name(struct net_device *dev, char *newname)
hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name));
write_unlock_bh(&dev_base_lock);
raw_notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev);
ret = raw_notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev);
ret = notifier_to_errno(ret);
if (ret) {
if (err) {
printk(KERN_ERR
"%s: name change rollback failed: %d.\n",
dev->name, ret);
} else {
err = ret;
memcpy(dev->name, oldname, IFNAMSIZ);
goto rollback;
}
}
return err;
}
@ -1058,20 +1076,43 @@ int dev_close(struct net_device *dev)
int register_netdevice_notifier(struct notifier_block *nb)
{
struct net_device *dev;
struct net_device *last;
int err;
rtnl_lock();
err = raw_notifier_chain_register(&netdev_chain, nb);
if (!err) {
for_each_netdev(dev) {
nb->notifier_call(nb, NETDEV_REGISTER, dev);
if (err)
goto unlock;
if (dev->flags & IFF_UP)
nb->notifier_call(nb, NETDEV_UP, dev);
}
for_each_netdev(dev) {
err = nb->notifier_call(nb, NETDEV_REGISTER, dev);
err = notifier_to_errno(err);
if (err)
goto rollback;
if (!(dev->flags & IFF_UP))
continue;
nb->notifier_call(nb, NETDEV_UP, dev);
}
unlock:
rtnl_unlock();
return err;
rollback:
last = dev;
for_each_netdev(dev) {
if (dev == last)
break;
if (dev->flags & IFF_UP) {
nb->notifier_call(nb, NETDEV_GOING_DOWN, dev);
nb->notifier_call(nb, NETDEV_DOWN, dev);
}
nb->notifier_call(nb, NETDEV_UNREGISTER, dev);
}
goto unlock;
}
/**
@ -3434,9 +3475,10 @@ int register_netdevice(struct net_device *dev)
write_unlock_bh(&dev_base_lock);
/* Notify protocols, that a new device appeared. */
raw_notifier_call_chain(&netdev_chain, NETDEV_REGISTER, dev);
ret = 0;
ret = raw_notifier_call_chain(&netdev_chain, NETDEV_REGISTER, dev);
ret = notifier_to_errno(ret);
if (ret)
unregister_netdevice(dev);
out:
return ret;