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283535 |
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25-May-2015 |
adrian |
Begin plumbing ieee80211_rx_stats through the receive path.
Smart NICs with firmware (eg wpi, iwn, the new atheros parts, the intel 7260 series, etc) support doing a lot of things in firmware. This includes but isn't limited to things like scanning, sending probe requests and receiving probe responses. However, net80211 doesn't know about any of this - it still drives the whole scan/probe infrastructure itself.
In order to move towards suppoting smart NICs, the receive path needs to know about the channel/details for each received packet. In at least the iwn and 7260 firmware (and I believe wpi, but I haven't tried it yet) it will do the scanning, power-save and off-channel buffering for you - all you need to do is handle receiving beacons and probe responses on channels that aren't what you're currently on. However the whole receive path is peppered with ic->ic_curchan and manual scan/powersave handling. The beacon parsing code also checks ic->ic_curchan to determine if the received beacon is on the correct channel or not.[1]
So:
* add freq/ieee values to ieee80211_rx_stats; * change ieee80211_parse_beacon() to accept the 'current' channel as an argument; * modify the iv_input() and iv_recv_mgmt() methods to include the rx_stats; * add a new method - ieee80211_lookup_channel_rxstats() - that looks up a channel based on the contents of ieee80211_rx_stats; * if it exists, use it in the mgmt path to switch the current channel (which still defaults to ic->ic_curchan) over to something determined by rx_stats.
This is enough to kick-start scan offload support in the Intel 7260 driver that Rui/I are working on. It also is a good start for scan offload support for a handful of existing NICs (wpi, iwn, some USB parts) and it'll very likely dramatically improve stability/performance there. It's not the whole thing - notably, we don't need to do powersave, we should not scan all channels, and we should leave probe request sending to the firmware and not do it ourselves. But, this allows for continued development on the above features whilst actually having a somewhat working NIC.
TODO:
* Finish tidying up how the net80211 input path works. Right now ieee80211_input / ieee80211_input_all act as the top-level that everything feeds into; it should change so the MIMO input routines are those and the legacy routines are phased out.
* The band selection should be done by the driver, not by the net80211 layer.
* ieee80211_lookup_channel_rxstats() only determines 11b or 11g channels for now - this is enough for scanning, but not 100% true in all cases. If we ever need to handle off-channel scan support for things like static-40MHz or static-80MHz, or turbo-G, or half/quarter rates, then we should extend this.
[1] This is a side effect of frequency-hopping and CCK modes - you can receive beacons when you think you're on a different channel. In particular, CCK (which is used by the low 11b rates, eg beacons!) is decodable from adjacent channels - just at a low SNR. FH is a side effect of having the hardware/firmware do the frequency hopping - it may pick up beacons transmitted from other FH networks that are in a different phase of hopping frequencies.
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257176 |
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26-Oct-2013 |
glebius |
The r48589 promised to remove implicit inclusion of if_var.h soon. Prepare to this event, adding if_var.h to files that do need it. Also, include all includes that now are included due to implicit pollution via if_var.h
Sponsored by: Netflix Sponsored by: Nginx, Inc.
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192468 |
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20-May-2009 |
sam |
Overhaul monitor mode handling: o replace DLT_IEEE802_11 support in net80211 with DLT_IEEE802_11_RADIO and remove explicit bpf support from wireless drivers; drivers now use ieee80211_radiotap_attach to setup shared data structures that hold the radiotap header for each packet tx/rx o remove rx timestamp from the rx path; it was used only by the tdma support for debugging and was mostly useless due to it being 32-bits and mostly unavailable o track DLT_IEEE80211_RADIO bpf attachments and maintain per-vap and per-com state when there are active taps o track the number of monitor mode vaps o use bpf tap and monitor mode vap state to decide when to collect radiotap state and dispatch frames; drivers no longer explicitly directly check bpf state or use bpf calls to tap frames o handle radiotap state updates on channel change in net80211; drivers should not do this (unless they bypass net80211 which is almost always a mistake) o update various drivers to be more consistent/correct in handling radiotap o update ral to include TSF in radiotap'd frames o add promisc mode callback to wi
Reviewed by: cbzimmer, rpaulo, thompsa
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