Patch "ath10k: fix soft lockup during firmware crash/hw-restart" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

ath10k: fix soft lockup during firmware crash/hw-restart

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ath10k-fix-soft-lockup-during-firmware-crash-hw-restart.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mohammed Shafi Shajakhan <[email protected]>
Date: Wed, 30 Nov 2016 10:59:29 +0530
Subject: ath10k: fix soft lockup during firmware crash/hw-restart

From: Mohammed Shafi Shajakhan <[email protected]>

commit c2cac2f74ab4bcf0db0dcf3a612f1e5b52d145c8 upstream.

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'

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

@@ -1534,7 +1534,7 @@ static void ath10k_core_restart(struct w
 	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;

@@ -4449,7 +4449,6 @@ static int ath10k_start(struct ieee80211
 		ar->state = ATH10K_STATE_ON;
 		break;
 	case ATH10K_STATE_RESTARTING:
-		ath10k_halt(ar);
 		ar->state = ATH10K_STATE_RESTARTED;
 		break;
 	case ATH10K_STATE_ON:

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/ath10k-fix-soft-lockup-during-firmware-crash-hw-restart.patch