On Tue, Nov 29, 2016 at 04:43:48PM -0800, Ben Greear wrote:

I have not seen this hang since adding this patch, so
hopefully it has resolved the problem.

thanks Ben ! I had updated the commit log with Fixes tag
https://patchwork.kernel.org/patch/9453609/

On 11/29/2016 06:46 AM, Mohammed Shafi Shajakhan wrote:

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'

Signed-off-by: Mohammed Shafi Shajakhan <redacted>
---
[thanks to Kalle and Michal for their inputs]

drivers/net/wireless/ath/ath10k/core.c | 2 +-
drivers/net/wireless/ath/ath10k/mac.c  | 1 -
2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
index 7005e2a..5bc6847 100644
--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c

@@ -1536,7 +1536,7 @@ static void ath10k_core_restart(struct work_struct *work)

	switch (ar->state) {
	case ATH10K_STATE_ON:
		ar->state = ATH10K_STATE_RESTARTING;
-		ath10k_hif_stop(ar);
+		ath10k_halt(ar);
		ath10k_scan_finish(ar);
		ieee80211_restart_hw(ar->hw);
		break;

diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index 717b2fa..481842b 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c

@@ -4449,7 +4449,6 @@ static int ath10k_start(struct ieee80211_hw *hw)

		ar->state = ATH10K_STATE_ON;
		break;
	case ATH10K_STATE_RESTARTING:
-		ath10k_halt(ar);
		ar->state = ATH10K_STATE_RESTARTED;
		break;
	case ATH10K_STATE_ON:

-- 
Ben Greear [off-list ref]
Candela Technologies Inc  http://www.candelatech.com