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

[Valo, Kalle]

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

-- 
Kalle Valo