Hi Johannes,
On 8/30/19 4:03 AM, Johannes Berg wrote:
On Fri, 2019-08-16 at 14:27 -0500, Denis Kenzior wrote:
If a (legacy) client requested a wiphy dump but did not provide the
NL80211_ATTR_SPLIT_WIPHY_DUMP attribute, the dump was supposed to be
composed of purely non-split NEW_WIPHY messages, with 1 wiphy per
message. At least this was the intent after commit:
3713b4e364ef ("nl80211: allow splitting wiphy information in dumps")
However, in reality the non-split dumps were broken very shortly after.
Perhaps around commit:
fe1abafd942f ("nl80211: re-add channel width and extended capa advertising")
Fun. I guess we updated all userspace quickly enough to not actually
have any issues there. As far as I remember, nobody ever complained, so
I guess people just updated their userspace.
Given that it's been 6+ years, maybe we're better off just removing the
whole non-split thing then, instead of fixing it. Seems even less likely
now that somebody would run a 6+yo supplicant (from before its commit
c30a4ab045ce ("nl80211: Fix mode settings with split wiphy dump")).
That would be my vote, given that we're probably one of a handful of
people in this world that understand that code path.
But... How would we handle non-dump versions of GET_WIPHY? To this day
I have dhcpcd issuing fun stuff like:
< Request: Get Wiphy (0x01) len 8 [ack]
0.374832
Interface Index: 59 (0x0000003b)
OTOH, this is a simple fix, would removing the non-split mode result in
any appreciable cleanups? Perhaps not, and we'd have to insert something
instead to reject non-split and log a warning, or whatnot.
Getting rid of the legacy non-split case would simplify things. We
could also be a-lot smarter about how we split up the messages in order
to utilize buffer space more efficiently. I think you cover this in
your other replies, but I haven't processed those yet.
Regards,
-Denis
