linux-kernel - Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27 (rc5, rc6, probably others)

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Date:	Fri, 19 Sep 2008 09:42:04 -0700 (PDT)
From:	Steven Noonan <steven@...inklabs.net>
To:	Senthil Balasubramanian <senthilkumar@...eros.com>
cc:	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, 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.
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