On 17-04-20 11:50 AM, David Miller wrote:
From: Jamal Hadi Salim <j...@mojatatu.com>
Date: Thu, 20 Apr 2017 09:27:00 -0400
The issue Jiri is bringing up is unrelated. He is talking about
a bitmap and conflating it with a data structure. They are not
the same issue.
Bitmaps can have the same exact problem as padding if we didn't code
it correctly.
The issue is _purely_, "did we check unused 'fields' and enforce them
to be a certain value"
If not, we lose, and can't use those "fields" in the future.
This rule applies whether you are speaking about padding or a bitmask.
There are no examples of such issues with bitmasks encapsulated in TLVs
that exist.
I grep iproute2 code and there are tons of example of bitmask flags
being sent in TLVs. They all start with:
u64/32/16 mybitflags = 0;
if i want foo then
mybitflags |= BRIDGE_FLAGS_SELF;
if i want bar then
mybitflags |= xxxx
addattr16/32/64(&req.n, sizeof(req), ATTR_XXX, mybitflags);
It does not make much sense to have a TLV for each of these
bits when i can fit a bunch of them in u16/32/64.
cheers,
jamal
