Adding a macro to define the vlog module in use adds a level of
indirection, which makes it easier to change how the vlog module must be
defined. A followup commit needs to do that, so getting these widespread
changes out of the way first should make that commit easier to review.
Fairly often it happens that nested Netlink attributes must themselves
contain Netlink attributes. In such a case, nlmsg_put_nested() is not so
convenient, because it requires the contents to be pre-assembled and then
copied into place. This commit introduces a new interface that instead
allows the nested attributes to be assembled in-place. As a demonstration,
it updates nl_msg_put_nested() to use this new interface.
Until now, if nl_sock_transact() received a reply that merely acknowledged
success, without providing any other payload, it would return success but
not provide the reply to its caller. This is inconsistent and could easily
cause a segfault in a caller that expects to see the reply on success, if
kernel behavior changed, for whatever reason, so that a request that
previously returned data now just returns an acknowledgment. In practice
this kind of change should never happen, but it is still better to handle
it properly.
I had assumed that nested Netlink attributes contained an entire Netlink
message, including header. This is wrong: they contain only a series of
attributes.
Nothing in the tree actually used nested attributes until now, so this
doesn't fix any existing bugs.
These two functions use their "sock" parameter only to figure out the
nlmsg_pid to put in the nlmsghdr. But that field can be filled in just
as well right before sending the message. Since our functions for sending
Netlink messages always modify the nlmsghdr anyhow (to fill in the length),
there is little benefit to filling in the nlmsg_pid in advance. The cost,
on the other hand, is having to pass another argument to functions that
already have too many. So this commit removes the argument.
Most of the timekeeping needs of OVS are simply to measure intervals,
which means that it is sensitive to changes in the clock. This commit
replaces the existing clocks with monotonic timers. An additional set
of wall clock timers are added and used in locations that need absolute
time.
Bug #1858
