Date: Mon, 02 Mar 2009 10:24:20 +0900 From: Nathan Butcher <n-butcher@fusiongol.com> To: Bengt Ahlgren <bengta@sics.se> Cc: freebsd-stable@freebsd.org, Sam Leffler <sam@freebsd.org>, Weongyo Jeong <weongyo@freebsd.org> Subject: Re: ural driver stalls under FreeBSD7.1 Message-ID: <49AB3544.6000008@fusiongol.com> In-Reply-To: <uh7d4d4rmel.fsf@P142.sics.se> References: <49A61894.5040804@fusiongol.com> <20090226045340.GC70144@weongyo.cdnetworks.kr> <uh7hc2h13a7.fsf@P142.sics.se> <49A74A21.1050109@freebsd.org> <20090227035532.GC72273@weongyo.cdnetworks.kr> <uh7d4d4rmel.fsf@P142.sics.se>
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Bengt Ahlgren wrote: > Weongyo Jeong <weongyo.jeong@gmail.com> writes: > >> On Thu, Feb 26, 2009 at 06:04:17PM -0800, Sam Leffler wrote: >>> Bengt Ahlgren wrote: >>>> Weongyo Jeong <weongyo.jeong@gmail.com> writes: >>>> >>>>> On Thu, Feb 26, 2009 at 01:20:36PM +0900, Nathan Butcher wrote: >>>>> >>>>>> I have a Buffalo WLI-U2-KG54-AI wireless USB adaptor. >>>>>> It has been malfunctioning for quite a while under FreeBSD7.0 and 7.1 >>>>>> >>>>>> Typically, It works for a while until eventually it stalls data >>>>>> transfers completely. It always seems to do this after an unspecified >>>>>> amount of time. >>>>>> >>>>>> I know the hardware isn't at fault because the device works fine under >>>>>> Linux. >>>>>> >>>>> Could you please check that `ifconfig <ifname> -bgscan' disabling the >>>>> background scan helps your symptom? >>>> The above sounds like the same problem as this: >>>> >>>> http://lists.freebsd.org/pipermail/freebsd-mobile/2009-February/011376.html >>>> http://lists.freebsd.org/pipermail/freebsd-mobile/2009-February/011343.html >>>> >>>> The problem is in the background scanning logic in sys/net80211. >>> I don't see how you come to this conclusion. ural is a totally >>> different driver than ath and so far as I can recall you never found the >>> cause for your problem w/ ath. Most of the usb wireless drivers do a >>> haphazard job of synchronizing async tasks like bg scan with the >>> foreground tx/rx processing. This can lead to firmware and/or usb >>> issues. ath does not have these issues but I am aware of at least one >>> problem w/ bg scanning in ath under RELENG_7 (that is not present in HEAD). >> I agree with sam because I saw some cases like stalls during background >> scanning that most of them I think it's caused by H/W miss-operation or >> miss-configuration by mistakes of driver. > > Looking into if_ural (1.69.6.1 - 7.1R version), it partly has the same > calls to net80211 which causes problems for ath. > > At line 1477, it has the same test as ath has to check for bg > scanning: > > if (ic->ic_flags & IEEE80211_F_SCAN) > ieee80211_cancel_scan(ic); > > That means that ieee80211_cancel_scan won't be called in the window > between when scan_next is run (which resets IEEE80211_F_SCAN), and > ieee80211_bg_scan is called the next time (setting IEEE80211_F_SCAN > again). This is the same problem as ath has. > > But I can't find that ural calls ieee80211_pwrsave to queue packets if > a bgscan was running. It seems that it just merrily tries to send > packets despite scanning is going on. > > Please note that even though ieee80211_cancel_scan IS called, that > won't take effect until the next clock tick. So if the output routine > just carries on with sending a packet, it will do so in the middle of > the scan. This is something that should be fixed in net80211. > > So, I find that ural also suffers from the problem with the scanning > logic in net80211. ...and turning bgscan off, as per Jeong's advice has solved the problem for me. So yes, background scanning is responsible for the hangs in ural.home | help
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