On Tue, Sep 14, 2010 at 9:42 AM, Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> wrote: > On Tue, Sep 14, 2010 at 9:39 AM, Luis R. Rodriguez > <lrodriguez@xxxxxxxxxxx> wrote: >> On Tue, Sep 14, 2010 at 8:00 AM, Luis R. Rodriguez >> <lrodriguez@xxxxxxxxxxx> wrote: >>> When we return to the home channel we were never reseting our beacon >>> timers, this was casued by the fact that the scanning flag was still >>> on even after we returned to our home channel. There are also other >>> reasons why we would get a reset and if we are not off channel >>> we always need to resynch our beacon timers, because a reset will >>> clear them. >>> >>> For more details refer to: >>> >>> http://code.google.com/p/chromium-os/issues/detail?id=5715 >>> >>> This bug is a regression introduced on 2.6.36. The order of the >>> changes are as follows: >>> >>> 5ee08656 - Sat Jul 31 - ath9k: prevent calibration during off-channel activity >>> a0daa0e7 - Tue Jul 27 - Revert "mac80211: fix sw scan bracketing" >>> 543708be - Fri Jun 18 - mac80211: fix sw scan bracketing >>> >>> mcgrof@tux ~/linux-2.6-allstable (git::master)$ git describe \ >>> --contains 5ee0865615f65f84e6ee9174771a6716c29e08e1 >>> v2.6.36-rc1~43^2~34^2~22 >>> >>> mcgrof@tux ~/linux-2.6-allstable (git::master)$ git describe \ >>> --contains a0daa0e7592ada797d6835f11529097aabc27ad2 >>> v2.6.36-rc1~571^2~64^2~13 >>> >>> mcgrof@tux ~/linux-2.6-allstable (git::master)$ git describe \ >>> --contains 543708be320d7df692d24b349ca01a947b340764 >>> v2.6.36-rc1~571^2~107^2~187 >>> >>> So 5ee08656 would have worked if a0daa0e7 was not committed but >>> it was so this means 5ee08656 was broken since it assumed that >>> when we were in the channel change routine the scan flag would >>> be lifted. As it turns out the scan flag will be set when we >>> are already on the home channel. >>> >>> These issues will need to be considered for our solution on >>> reshifting the scan complete callback location on mac80211 on >>> current development kernel work. >>> >>> This patch has stable fixes which apply down to [2.6.36+] >>> >>> Cc: stable@xxxxxxxxxx >>> Cc: Paul Stewart <pstew@xxxxxxxxxx> >>> Cc: Amod Bodas <amod.bodas@xxxxxxxxxxx> >>> Signed-off-by: Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> >>> --- >>> >>> This v2 clarifies the second to last sentence, on the v1 this >>> was just jiberish on my first read.. this should clarify what >>> I meant. >>> >>> drivers/net/wireless/ath/ath9k/main.c | 6 ++++-- >>> 1 files changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c >>> index ba029b2..e349619 100644 >>> --- a/drivers/net/wireless/ath/ath9k/main.c >>> +++ b/drivers/net/wireless/ath/ath9k/main.c >>> @@ -258,9 +258,11 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw, >>> if (!(sc->sc_flags & (SC_OP_OFFCHANNEL | SC_OP_SCANNING))) { >>> ath_start_ani(common); >>> ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work, 0); >>> - ath_beacon_config(sc, NULL); >>> } >>> >>> + if (!(sc->sc_flags & (SC_OP_OFFCHANNEL))) >>> + ath_beacon_config(sc, NULL); >>> + >> >> Upon further thought this change should just remove the SC_OP_SCANNING >> flag from above and let the code there run when we are not off >> channel. Reason is that as I noted above on the commit log entry the >> scan flag will be set even when we return to the home channel due to >> the races in mac80211 that were actually fixed by Johannes but later >> reverted due to issues. Doing the fix this way would also let us >> re-arm ANI and the tx completion monitor, this was also broken! I'll >> respin this patch shortly after some basic testing. > > I should also note that this patch fixes the issue of reseting the > beacon timers upon a reset, likely when the tx monitor hits -- I > suspect that when that currently would hit we'd actually be out of > synch with the AP and disconnect. This patch fixes that, but I just > reviewed older kernels and the offchannel flag was not available prior > to 2.6.36 so we can only fix this properly on >= 2.6.36 unless we > figure out a way to annotate we're on the home channel. If we do we > can potentially propagate a fix down to older kernels than 2.6.36 > eventually. Fun, just noticed these would be busted too :) ath9k_hw_startpcureceive(ah, (sc->sc_flags & SC_OP_SCANNING)); Ah, joy. /me fixes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
