[ath9k-devel] [PATCH] ath9k: Fix softlockup in AR9485

[John W. Linville <linville@tuxdriver.com>]

Do you have a version that applies to 3.5 and earlier?

On Tue, Jun 12, 2012 at 08:13:43PM +0530, Mohammed Shafi Shajakhan wrote:
> From: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
> 
> steps to recreate:
> load latest ath9k driver with AR9485
> stop the network-manager and wpa_supplicant
> bring the interface up
> 
> 	Call Trace:
> 	[<ffffffffa0517490>] ? ath_hw_check+0xe0/0xe0 [ath9k]
> 	[<ffffffff812cd1e8>] __const_udelay+0x28/0x30
> 	[<ffffffffa03bae7a>] ar9003_get_pll_sqsum_dvc+0x4a/0x80 [ath9k_hw]
> 	[<ffffffffa05174eb>] ath_hw_pll_work+0x5b/0xe0 [ath9k]
> 	[<ffffffff810744fe>] process_one_work+0x11e/0x470
> 	[<ffffffff8107530f>] worker_thread+0x15f/0x360
> 	[<ffffffff810751b0>] ? manage_workers+0x230/0x230
> 	[<ffffffff81079af3>] kthread+0x93/0xa0
> 	[<ffffffff815fd3a4>] kernel_thread_helper+0x4/0x10
> 	[<ffffffff81079a60>] ? kthread_freezable_should_stop+0x70/0x70
> 	[<ffffffff815fd3a0>] ? gs_change+0x13/0x13
> 
> ensure that the PLL-WAR for AR9485/AR9340 is executed only if the STA is
> associated (or) IBSS/AP mode had started beaconing. Ideally this WAR
> is needed to recover from some rare beacon stuck during stress testing.
> Before the STA is associated/IBSS had started beaconing, PLL4(0x1618c)
> always seem to have zero even though we had configured PLL3(0x16188) to
> query about PLL's locking status. When we keep on polling infinitely PLL4's
> 8th bit(ie check for PLL locking measurements is done), machine hangs
> due to softlockup.
> 
> fixes https://bugzilla.redhat.com/show_bug.cgi?id=811142
> 
> Reported-by: Rolf Offermanns <rolf.offermanns@gmx.net>
> Cc: stable at vger.kernel.org
> Tested-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
> Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
> ---
>  drivers/net/wireless/ath/ath9k/link.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath9k/link.c b/drivers/net/wireless/ath/ath9k/link.c
> index 0cc4c70..a105c94 100644
> --- a/drivers/net/wireless/ath/ath9k/link.c
> +++ b/drivers/net/wireless/ath/ath9k/link.c
> @@ -136,6 +136,14 @@ void ath_hw_pll_work(struct work_struct *work)
>  	u32 pll_sqsum;
>  	struct ath_softc *sc = container_of(work, struct ath_softc,
>  					    hw_pll_work.work);
> +	/*
> +	 * ensure that the PLL WAR is executed only
> +	 * after the STA is associated (or) if the
> +	 * beaconing had started in interfaces that
> +	 * uses beacons.
> +	 */
> +	if (!test_bit(SC_OP_BEACONS, &sc->sc_flags))
> +		return;
>  
>  	ath9k_ps_wakeup(sc);
>  	pll_sqsum = ar9003_get_pll_sqsum_dvc(sc->sc_ah);
> -- 
> 1.7.0.4
> 
> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.