Date: Fri, 17 Feb 2012 02:50:11 GMT From: Adrian Chadd <adrian@FreeBSD.org> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/165220: [ath] "ath_rx_tasklet: sc_inreset_cnt > 0; skipping" messages Message-ID: <201202170250.q1H2oB7u022658@red.freebsd.org> Resent-Message-ID: <201202170300.q1H30LqS011869@freefall.freebsd.org>
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>Number: 165220 >Category: kern >Synopsis: [ath] "ath_rx_tasklet: sc_inreset_cnt > 0; skipping" messages >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Feb 17 03:00:21 UTC 2012 >Closed-Date: >Last-Modified: >Originator: Adrian Chadd >Release: 9.0-RELEASE i386, with -HEAD net80211/ath >Organization: >Environment: >Description: There are far too many of the following messages showing up: [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping [100191] ath0: ath_start: sc_inreset_cnt > 0; bailing [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping [100191] ath0: ath_rx_tasklet: sc_inreset_cnt > 0; skipping . What's happening is that a bunch of TX or RX completion is occuring at the same time as a channel change/reset. The previous code just had these run concurrently, causing all kinds of random and weird behaviour. I introduced some debugging in FreeBSD-HEAD that tries to (a) stop these and (b) log when they occur, so I could actually try finding/figuring out what's going on. This is one of these cases. :-) >How-To-Repeat: Just run ath :-) >Fix: The problem is that although interrupts are disabled in reset, the ath taskqueue may currently be running and this means existing TX completion and RX will occur. I think the fix is to do this: * grab the PCU lock * disable interrupts * grab the reset counter * stop the ath taskqueue and wait for pending tasks to complete . but is this still racy? A patch I've done to do the above in ath_reset() and ath_chan_change() reduces the instances of this quite heavily but it still occasionally turns up. >Release-Note: >Audit-Trail: >Unformatted:
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