This function combines what dpif_create() and dpif_open() do. It allows
us to factor a tiny amount of code out of the vswitch, but more importantly
this function is also useful in the following commit.
Originally, the function dp_enumerate() initialized the 'all_dps'
argument. This is inconsistent with most other functions that take an
svec argument, which would only clear the contents. Further, if someone
were not careful when reusing the svec, it could lead to memory leaks.
With this change, the caller is expected to first call svec_init() on
the argument.
This new abstraction layer allows multiple implementations of network
devices in a single running process. This will be useful, for example, to
support network devices that are simulated entirely in the running process
or that communicate with other processes over Unix domain sockets, etc.
The reimplemented tap device support in this commit has not been tested.
At startup, the vswitch needs to delete datapaths that are not configured
by the administrator. Until now this was done by knowing the possible
names of Linux datapaths. This commit cleans up by allowing each
datapath class to enumerate its existing datapaths and their names.
The dpif and netdev code has had various ways to check for changes to
dpifs and netdevs over the course of Open vSwitch development. All of
these have been thus far fairly specific to the Linux implementation. This
commit is the start of a more general API for watching for such changes.
The dpif-related parts seem fairly mature and so they are documented,
the netdev parts will probably need to change somewhat and so they are
not documented yet.
This commit initially introduces only a single datapath implementation,
which is the same as the original one, but it paves the way for
additional implementations, such as the upcoming userspace datapath.
Until now, ODP_PORT_LIST has reported the number of ports actually copied
out. It's better for the caller, however, if it reports the number of
ports that were available to be copied out.
Soon we will allow for multiple datapath implementations. By allowing
the datapath to choose the port numbers, we possibly simplify some datapath
implementations, and the datapath's clients don't have to guess (or to
check) what port numbers are free, so this seems like a better way to go.
This function is easier for callers to use if they do not have to guess
how many ports are in the group. Since it's not performance critical at
all, introduce these easier semantics.
One potential user of dpif_port_query_by_name() actually open-coded the
function because it didn't want logging on failure. There was only one
actual caller of the function, which didn't want logging on failure either.
So, clean up by reducing the failure log level to DBG and making the
open-coded version an actual caller.
dpif_id() is often used in error messages, e.g. "dp%u: screwed up". But
soon we will be generalizing the concept of a datapath, so it is better
to have a function that returns a full name, e.g. "%s: screwed up".
Accordingly, this commit replaces dpif_id() by a new function dpif_name()
that does so.
The 'minor' member of struct dpif is used for two different purposes:
for printing in log messages and for encapsulating in NetFlow messages.
The needs in each case are different, so we should break up these uses.
This commit does half of that, by introducing a new function to retrieve
NetFlow ids and using it where appropriate.
With multiple kinds of datapaths, code should not just use
"dp%u" along with dpif_minor() to print a datapath name, because not all
datapaths can sensibly be named that way. We want to use a function
with a name like dpif_get_name() to retrieve a datapath name for printing
to the user, in which case the existing dpif_get_name() function would be
confusing. So rename the existing one to something more explicit.
