Date:	Fri, 19 Sep 2008 23:28:24 +0530
From:	Senthil Balasubramanian <senthilkumar@...eros.com>
To:	Steven Noonan <steven@...inklabs.net>
CC:	Senthilkumar Balasubramanian 
	<Senthilkumar.Balasubramanian@...eros.com>,
	Luis Rodriguez <Luis.Rodriguez@...eros.com>,
	Ingo Molnar <mingo@...e.hu>,
	"ath9k-devel@...ts.ath9k.org" <ath9k-devel@...ts.ath9k.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27
	(rc5, rc6, probably others)

On Fri, Sep 19, 2008 at 10:12:04PM +0530, Steven Noonan wrote:
> 
> 
> On Fri, 19 Sep 2008, Senthil Balasubramanian wrote:
> 
> > On Fri, Sep 19, 2008 at 12:59:29PM +0530, Steven Noonan wrote:
> > > On Thu, Sep 18, 2008 at 8:01 PM, Luis R. Rodriguez
> > > <lrodriguez@...eros.com> wrote:
> > > > Thanks for testing, and glad to see this is resolved.
> > > >
> > >
> > > Damn. It's back. I was using wireless normally this evening. Browsing
> > > the web, that kind of thing, and then the wireless inexplicably
> > > dropped (even with the group rekeying patch), so I unloaded/reloaded
> > > the module. This popped up in dmesg:
> > >
> > > [ 3834.375658] vendor=8086 device=27d2
> > > [ 3834.375666] ath9k 0000:03:00.0: PCI INT A disabled
> > > [ 3834.375716] ath9k: driver unloaded
> > > [ 3838.552419] ath9k: 0.1
> > > [ 3838.552502] vendor=8086 device=27d2
> > > [ 3838.552511] ath9k 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
> > > [ 3838.552532] ath9k 0000:03:00.0: setting latency timer to 64
> > > [ 3838.688924] phy1: Selected rate control algorithm 'ath9k_rate_control'
> > > [ 3838.693652] phy1: Atheros 5416: mem=0xffffc20000060000, irq=17
> > > [ 3839.427125] irq 17: nobody cared (try booting with the "irqpoll" option)
> > > [ 3839.427136] Pid: 0, comm: swapper Tainted: P
> > > 2.6.27-rc6-tip-00478-g74f1a36 #1
> > > [ 3839.427141] Call Trace:
> > > [ 3839.427145]  <IRQ>  [<ffffffff802219c5>] ? read_hpet+0x9/0x1c
> > > [ 3839.427165]  [<ffffffff8026af71>] __report_bad_irq+0x3d/0x8c
> > > [ 3839.427172]  [<ffffffff8026b0c6>] note_interrupt+0x106/0x160
> > > [ 3839.427180]  [<ffffffff8026b801>] handle_fasteoi_irq+0xad/0xda
> > > [ 3839.427188]  [<ffffffff8020f7b0>] do_IRQ+0x10c/0x190
> > > [ 3839.427194]  [<ffffffff8020c551>] ret_from_intr+0x0/0xa
> > > [ 3839.427198]  <EOI>  [<ffffffff8026c6f0>] rcu_pending+0x62/0x6e
> > > [ 3839.427211]  [<ffffffff8025bc11>] ? tick_nohz_stop_sched_tick+0x2e4/0x2f3
> > > [ 3839.427218]  [<ffffffff8020ad94>] cpu_idle+0x7b/0xdb
> > > [ 3839.427226]  [<ffffffff8060c921>] rest_init+0x75/0x77
> > > [ 3839.427231] handlers:
> > > [ 3839.427234] [<ffffffffa0240238>] (ath_isr+0x0/0x170 [ath9k])
> > > [ 3839.427263] Disabling IRQ #17
> > > [ 3842.263699] ADDRCONF(NETDEV_UP): wlan0: link is not ready
> > > [ 3848.035003] ADDRCONF(NETDEV_UP): wlan0: link is not ready
> > > [ 3848.432701] ADDRCONF(NETDEV_UP): wlan0: link is not ready
> > > [ 3850.216947] wlan0: authenticate with AP 00:1e:52:79:4d:01
> > > [ 3850.217027] wlan0: authenticate with AP 00:1e:52:79:4d:01
> > > [ 3850.228326] wlan0: authenticated
> > > [ 3850.228336] wlan0: associate with AP 00:1e:52:79:4d:01
> > > [ 3850.428140] wlan0: associate with AP 00:1e:52:79:4d:01
> > > [ 3850.628151] wlan0: associate with AP 00:1e:52:79:4d:01
> > > [ 3850.728305] wlan0: RX AssocResp from 00:1e:52:79:4d:01 (capab=0x431
> > > status=0 aid=1)
> > > [ 3850.728314] wlan0: associated
> > > [ 3850.728655] wlan0 (WE) : Wireless Event too big (320)
> > > [ 3850.743377] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
> > > [ 3860.855104] wlan0: no IPv6 routers present
> > >
> > > I rebuilt the module with DBG_ATH_INTERRUPT, but it somehow stumbled
> > > itself back into working order while I was compiling. I can't keep the
> > > interrupt debugging on all the time because it's just -too verbose-,
> > > and when I pop a debug version of the module in, then it's too late to
> > > track the issue....
> >
> > I am able to reproduce this IRQ nobody cared issue in my setup and the
> > following patch seems to be fixing the issue. Please try it out and let
> > me know if it solves your issue in your setup.
> 
> The patch you prvide doesn't want to apply. What code did you base this
> on?
> 
> The first change listed doesn't work because there is no tasklet_kill() in
> core.c, and the line immediately after ath_stop there has
> "!sc->sc_invalid" instead of the "!(sc->sc_flags & SC_OP_INVALID)".
> 
> The second fails because SC_OP_INVALID isn't defined.
> 
> However, if your patch did apply to my code, I bet it'd solve the issue,
> based on what it says it does.

I am on 2.6.27-rc6 and this patch is on top of my earlier patch
titled "[PATCH] ath9k: connectivity is lost after Group rekeying is
done". However this patch can be applied on top of latest wireless testing
too. I could apply this patch succesfully on top of wireless testing
git tree.

My git-describe says v2.6.27-rc6-1378-g34e512f.

There is no sc_invalid flag in "struct ath_softc" today. Where did
you get this variable from? It was removed in the following commit

-----------------------------------------------
commit f2c9705a05ecbc0d94216a3b042d5641e8bf70b1
Author: Sujith <Sujith.Manoharan@...eros.com>
Date:   Mon Aug 11 14:05:08 2008 +0530

    ath9k: Use bitfields for sc operations

    Signed-off-by: Sujith Manoharan <Sujith.Manoharan@...eros.com>
    Signed-off-by: John W. Linville <linville@...driver.com>
-----------------------------------------------

Which code base are you using?
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