Return-path: Received: from server.eikelenboom.it ([91.121.65.215]:56044 "EHLO server.eikelenboom.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935105AbdEWST0 (ORCPT ); Tue, 23 May 2017 14:19:26 -0400 Subject: Re: 4.12-RC2 BUG: scheduling while atomic: irq/47-iwlwifi To: Arend Van Spriel , Johannes Berg Cc: linux-wireless , netdev@vger.kernel.org References: <1495450628.2653.14.camel@sipsolutions.net> <764a929c-ce8a-c859-a49e-2f20cb05ae44@broadcom.com> <532c257e-52a0-18c1-1afe-04d37c28e072@broadcom.com> From: Sander Eikelenboom Message-ID: (sfid-20170523_201940_660258_90C87563) Date: Tue, 23 May 2017 19:51:12 +0200 MIME-Version: 1.0 In-Reply-To: <532c257e-52a0-18c1-1afe-04d37c28e072@broadcom.com> Content-Type: text/plain; charset=utf-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 22/05/17 23:02, Arend Van Spriel wrote: > > > On 22-5-2017 14:09, Arend van Spriel wrote: >> On 5/22/2017 12:57 PM, Johannes Berg wrote: >>> On Mon, 2017-05-22 at 12:36 +0200, Sander Eikelenboom wrote: >>>> Hi, >>>> >>>> I encountered this splat with 4.12-RC2. >>> >>> Ugh, yeah, I should've seen that in the review. >>> >>> Arend, please take a look at this. cfg80211_sched_scan_results() cannot >>> sleep, so you can't rtnl_lock() in there. Looks like you can just rely >>> on RCU though? >> >> I see. I think you are right on RCU. Don't have the code in front of me >> now, but I think the lookup has an ASSERT_RTNL. Will look into it after >> my monday meeting :-p > > I realized I have a laptop lying around with intel 3160 wifi chip and > tried to reproduce the issue. Did not run into the splat running > 4.12-rc1 from wireless-drivers-next repo. I did not get the email from > Sander so I don't know any details. > > Here is what I changed based on the info Johannes provided. Can you > please check if this get rid of the splat and let me know. Hi Arend, I ran your patch today, so far no issues. -- Sander > Regards, > Arend > --- > diff --git a/net/wireless/scan.c b/net/wireless/scan.c > index 14d5f0c..04833bb 100644 > --- a/net/wireless/scan.c > +++ b/net/wireless/scan.c > @@ -322,9 +322,7 @@ static void cfg80211_del_sched_scan_req(struct > cfg80211_regi > { > struct cfg80211_sched_scan_request *pos; > > - ASSERT_RTNL(); > - > - list_for_each_entry(pos, &rdev->sched_scan_req_list, list) { > + list_for_each_entry_rcu(pos, &rdev->sched_scan_req_list, list) { > if (pos->reqid == reqid) > return pos; > } > @@ -398,13 +396,13 @@ void cfg80211_sched_scan_results(struct wiphy > *wiphy, u64 > trace_cfg80211_sched_scan_results(wiphy, reqid); > /* ignore if we're not scanning */ > > - rtnl_lock(); > + rcu_read_lock(); > request = cfg80211_find_sched_scan_req(rdev, reqid); > if (request) { > request->report_results = true; > queue_work(cfg80211_wq, &rdev->sched_scan_res_wk); > } > - rtnl_unlock(); > + rcu_read_unlock(); > } > EXPORT_SYMBOL(cfg80211_sched_scan_results); > >