This was a somewhat difficult merge since there was a fair amount of
superficially divergent development on the two branches, especially in the
datapath.
This has been build-tested against XenServer 5.5.0 and XenServer 5.7.0
build 15122. It has been booted and connected to XenCenter on 5.5.0.
The merge revealed a couple of outstanding bugs, which will be fixed on
citrix and then merged back into master.
We create symlinks from /sys/class/net/<bridgename>/brif/<devname> to
/sys/class/net/<devname>/brport, but until now we have never updated the
links when network devices are renamed. This commit fixes this problem.
(Only the <devname> in /sys/class/net/<bridgename>/brif/<devname> needs to
be updated. Symlinks within sysfs have stable targets; that is, no matter
how the object that a sysfs symlink points to moves around, the link is
still maintained correctly.)
Until now, when dp_sysfs_add_if() failed, the caller ignored the failure.
This is a minor problem, because everything else should continue working,
without sysfs entries for the interface, in theory anyhow. In actual
practice, the error exit path of dp_sysfs_add_if() does a kobject_put(),
and that kobject_put() calls release_nbp(), so that the new port gets
freed. The next reference to the new port (usually in an ovs-vswitchd call
to the ODP_PORT_LIST ioctl) will then use the freed data and probably OOPS.
The fix is to make the datapath code, as opposed to the sysfs code,
responsible for creating and destroying the net_bridge_port kobject. The
dp_sysfs_{add,del}_if() functions then just attach and detach the kobject
to sysfs and their cleanup routines no longer need to destroy the kobject
and indeed we don't care whether dp_sysfs_add_if() really succeeds.
This commit also makes the same transformation to the datapath's ifobj,
for consistency.
It is easy to trigger the OOPS fixed by this commit by adding a network
device A to a datapath, then renaming network device A to B, then renaming
network device C to A, then adding A to the datapath. The last attempt to
add A will fail because a file named /sys/class/net/<datapath>/brif/A
already exists from the time that C was added to the datapath under the
name A.
This commit also adds some compatibility infrastructure, because it moves
code out of #ifdef SUPPORT_SYSFS and it otherwise wouldn't build.
The following commit will move the initialization of the datapath and
net_bridge_port kobjects earlier and the destruction later, without
changing when those kobjects are attached to sysfs. To do so, the
initialization of kobjects and attaching to sysfs has to be done as
separate steps. That's already the case for net_bridge_port kobjects, and
this commit makes it so for datapath kobjects too.
This commit also simplifies some code, since the split API exists both
before and after 2.6.25, but the combined functions changed names.
Also, in dp_sysfs_add_if() call kobject_init() after initializing the
kset member, since kobject_init() expects that. This makes no actual
difference in this case since the kobj is obtained from kzalloc(), but
it still seems better.
