package/kernel/mac80211/patches/333-ath10k-Fix-soft-lockup-during-firmware-crash-hw-rest.patch

   1 From: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
   2 Date: Wed, 30 Nov 2016 10:59:29 +0530
   3 Subject: [PATCH] ath10k: Fix soft lockup during firmware crash/hw-restart
   4
   5 During firmware crash (or) user requested manual restart
   6 the system gets into a soft lock up state because of the
   7 below root cause.
   8
   9 During user requested hardware restart / firmware crash
  10 the system goes into a soft lockup state as 'napi_synchronize'
  11 is called after 'napi_disable' (which sets 'NAPI_STATE_SCHED'
  12 bit) and it sleeps into infinite loop as it waits for
  13 'NAPI_STATE_SCHED' to be cleared. This condition is hit because
  14 'ath10k_hif_stop' is called twice as below (resulting in calling
  15 'napi_synchronize' after 'napi_disable')
  16
  17 'ath10k_core_restart' -> 'ath10k_hif_stop' (ATH10K_STATE_ON) ->
  18 -> 'ieee80211_restart_hw' -> 'ath10k_start' -> 'ath10k_halt' ->
  19 'ath10k_core_stop' -> 'ath10k_hif_stop' (ATH10K_STATE_RESTARTING)
  20
  21 Fix this by calling 'ath10k_halt' in ath10k_core_restart itself
  22 as it makes more sense before informing mac80211 to restart h/w
  23 Also remove 'ath10k_halt' in ath10k_start for the state of 'restarting'
  24
  25 Fixes: 3c97f5de1f28 ("ath10k: implement NAPI support")
  26 Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
  27 ---
  28
  29 --- a/drivers/net/wireless/ath/ath10k/core.c
  30 +++ b/drivers/net/wireless/ath/ath10k/core.c
  31 @@ -1534,7 +1534,7 @@ static void ath10k_core_restart(struct w
  32         switch (ar->state) {
  33         case ATH10K_STATE_ON:
  34                 ar->state = ATH10K_STATE_RESTARTING;
  35 -               ath10k_hif_stop(ar);
  36 +               ath10k_halt(ar);
  37                 ath10k_scan_finish(ar);
  38                 ieee80211_restart_hw(ar->hw);
  39                 break;
  40 --- a/drivers/net/wireless/ath/ath10k/mac.c
  41 +++ b/drivers/net/wireless/ath/ath10k/mac.c
  42 @@ -4470,7 +4470,6 @@ static int ath10k_start(struct ieee80211
  43                 ar->state = ATH10K_STATE_ON;
  44                 break;
  45         case ATH10K_STATE_RESTARTING:
  46 -               ath10k_halt(ar);
  47                 ar->state = ATH10K_STATE_RESTARTED;
  48                 break;
  49         case ATH10K_STATE_ON: