Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:56078 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757054AbcLAGGm (ORCPT ); Thu, 1 Dec 2016 01:06:42 -0500 Date: Thu, 1 Dec 2016 11:36:31 +0530 From: Mohammed Shafi Shajakhan To: Ben Greear Cc: Mohammed Shafi Shajakhan , ath10k@lists.infradead.org, linux-wireless@vger.kernel.org Subject: Re: ath10k: Fix soft lockup during firmware crash/hw-restart Message-ID: <20161201060612.GA8611@atheros-ThinkPad-T61> (sfid-20161201_070645_597372_0C8B75E1) References: <1480430762-15995-1-git-send-email-mohammed@qca.qualcomm.com> <1a44a3e9-3d67-30a5-0325-a65003ebe1fc@candelatech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1a44a3e9-3d67-30a5-0325-a65003ebe1fc@candelatech.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, Nov 29, 2016 at 10:16:50AM -0800, Ben Greear wrote: > Is this something for stable? And if so, how far back should it be applied? @Kalle, [shafi] kindly suggest. If i am not wrong this is only needed for 4.9 > > I'll add this patch to my 4.9 tree and test it... > [shafi] thanks a lot Ben. > > On 11/29/2016 06:46 AM, Mohammed Shafi Shajakhan wrote: > >From: Mohammed Shafi Shajakhan > > > >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 > >--- > >[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 > Candela Technologies Inc http://www.candelatech.com >