[PATCH v2] ath10k: Fix soft lockup during firmware crash/hw-restart

[Mohammed Shafi Shajakhan]

On Thu, Dec 01, 2016 at 10:35:38AM +0000, Valo, Kalle wrote:
> Mohammed Shafi Shajakhan <mohammed at qti.qualcomm.com> writes:
> 
> > From: Mohammed Shafi Shajakhan <mohammed at qti.qualcomm.com>
> >
> > During firmware crash (or) user requested manual restart
> > the system gets into a soft lock up state because of the
> > below root cause.
> >
> > During user requested hardware restart / firmware crash
> > the system goes into a soft lockup state as 'napi_synchronize'
> > is called after 'napi_disable' (which sets 'NAPI_STATE_SCHED'
> > bit) and it sleeps into infinite loop as it waits for
> > 'NAPI_STATE_SCHED' to be cleared. This condition is hit because
> > 'ath10k_hif_stop' is called twice as below (resulting in calling
> > 'napi_synchronize' after 'napi_disable')
> >
> > 'ath10k_core_restart' -> 'ath10k_hif_stop' (ATH10K_STATE_ON) ->
> > -> 'ieee80211_restart_hw' -> 'ath10k_start' -> 'ath10k_halt' ->
> > 'ath10k_core_stop' -> 'ath10k_hif_stop' (ATH10K_STATE_RESTARTING)
> >
> > Fix this by calling 'ath10k_halt' in ath10k_core_restart itself
> > as it makes more sense before informing mac80211 to restart h/w
> > Also remove 'ath10k_halt' in ath10k_start for the state of 'restarting'
> >
> > Fixes: 3c97f5de1f28 ("ath10k: implement NAPI support")
> > Signed-off-by: Mohammed Shafi Shajakhan <mohammed at qti.qualcomm.com>
> > ---
> > [v2 Added Fixes ]
> 
> I'll also add:
> 
> Cc: <stable at vger.kernel.org> # v4.9
>
thank you Kalle.

regards,
shafi