From patchwork Mon May 22 21:02:34 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arend Van Spriel X-Patchwork-Id: 765588 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3wWrhf72DTz9s65 for ; Tue, 23 May 2017 07:02:42 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=broadcom.com header.i=@broadcom.com header.b="RjSzUNLB"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933982AbdEVVCk (ORCPT ); Mon, 22 May 2017 17:02:40 -0400 Received: from mail-pf0-f171.google.com ([209.85.192.171]:34301 "EHLO mail-pf0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933847AbdEVVCi (ORCPT ); Mon, 22 May 2017 17:02:38 -0400 Received: by mail-pf0-f171.google.com with SMTP id 9so93221837pfj.1 for ; Mon, 22 May 2017 14:02:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding; bh=Z3De8SL+3kziCOt4nCoCZEuuGF7QA7RoQM24Gfjkd0g=; b=RjSzUNLBe9mIusEPc4gbIelYCNTkp7tJmOtTuJncR13YuWxWptaFhGfQhPMzEn6rw9 RFtCF6viv5nBRI8vx8CXyratNrmuU+ZDURruDihqzlxOa7h5oS/YQ1H+GpUwjZqGK/2k VuQ3tzKbJvACTzgOjicYHNDLHtSHPj2kHf/Fc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=Z3De8SL+3kziCOt4nCoCZEuuGF7QA7RoQM24Gfjkd0g=; b=RRbYKVF94qqF8cLchmsqbCFS7iHUlMuq8M3gn/y0QlXowS4C4E+eejj89G6Jq2mlSf 1qBj2+IAhfgceWUt83UMth0dlSIOIpI5d9Z5fSiBMwcJAOGzEY9ZIkZsVfrizSRiXfBf luKjF7TxUmGXbmrEhSOo2JNX67jIGM3yA4d4RtOPREIjWQFlqKsg2tZi3j7w6U1XFW0G m5chPGI+gi6MGW/zB9Z7wbhuLHEd/XRE1VL6pMpThgfiZibhNZt7UciFflg8VWQ/+bkd Jwmj9+1j1n7QKWoMip3c6i0RTEbrZ6tP+4fxgGAmAE5CSfTKsJszWfi9q19YkGvH6lci usmg== X-Gm-Message-State: AODbwcDenVNxcQoZdjoiwdI/NfDmvb+a/7/smROxpqxk+i9kV5kXz32l mA/Ezkvfuw9GUPcL X-Received: by 10.98.70.17 with SMTP id t17mr28157280pfa.229.1495486958007; Mon, 22 May 2017 14:02:38 -0700 (PDT) Received: from [10.177.251.3] ([192.19.248.250]) by smtp.gmail.com with ESMTPSA id q9sm29423678pfg.77.2017.05.22.14.02.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 May 2017 14:02:37 -0700 (PDT) Subject: Re: 4.12-RC2 BUG: scheduling while atomic: irq/47-iwlwifi To: Johannes Berg , Sander Eikelenboom References: <1495450628.2653.14.camel@sipsolutions.net> <764a929c-ce8a-c859-a49e-2f20cb05ae44@broadcom.com> Cc: linux-wireless , netdev@vger.kernel.org From: Arend Van Spriel Message-ID: <532c257e-52a0-18c1-1afe-04d37c28e072@broadcom.com> Date: Mon, 22 May 2017 23:02:34 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <764a929c-ce8a-c859-a49e-2f20cb05ae44@broadcom.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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. Regards, Arend --- } @@ -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); 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;