On Thu, Dec 01, 2016 at 10:35:38AM +0000, Valo, Kalle wrote:

Mohammed Shafi Shajakhan [off-list ref] writes:

quoted

From: Mohammed Shafi Shajakhan <redacted>

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 <redacted>
---
[v2 Added Fixes ]

I'll also add:

Cc: <redacted> # v4.9

thank you Kalle.

regards,
shafi