Received: by 2002:a25:e74b:0:0:0:0:0 with SMTP id e72csp1605229ybh; Thu, 23 Jul 2020 13:10:33 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw3aJLnZSOsbliuQkBNy749sCsdQzmmpeHdXzMLc86q9MJXZrsGWGCwcmhWIWjrPditKnz3 X-Received: by 2002:a17:906:cc13:: with SMTP id ml19mr5959409ejb.288.1595535033428; Thu, 23 Jul 2020 13:10:33 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1595535033; cv=none; d=google.com; s=arc-20160816; b=uajvaUTr+eyxdBlzfqzcWcRdf6omS48pfH8vKE2qMnNc0mdKjb01Wie6G/As++MRsw jmXg6e9U6FiDvn44amGIn+s4e+J8GhfbkWadHdGYOVc9IK9ELCDS2gXJd+PHGM+8DdNd Bgw7Q/L+uw95a+vYWY1ZaM+YY4siMs2SKo9+n7yQ3U4/irFp1xuHsqzvVT7zE8n5jfED suSsLCondkL2QYGGdkEkBtlB64CS+V3zYphJ0XHOYZB+mrX0wpcFMMf9X7BzPBDs81tv osmI/94zXTI4B10pcIKP6kADhGo9StZ9SSDoNLAnIQoWgC3uJkq61OryuX3Jm5nMJEDR IYZg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:date:cc:to:from:subject :message-id; bh=HeDO0TMqGVH6MDVHrWr6rk2QhQZfoARRD3p3oVjv6MQ=; b=Py1dtFIhN3hVadxSjcT1RNXrzFHj7VSxeMcVeX/UPtv6QNcWSzO0Az5TWh39g6pC6f Bhm9jb2SIBeOJUl4d5CbX3T728ne3aJdxX4p0GsGjNBVqPkS2F4W1cdD2RcsQGhdiDtv /O5RVKJxXDv+ofQsWEcKi7HLD+Vwe0wGnpwjQBoaQWsEz4ohACngOk2df3tN6u9QaJe2 dYS+DfQ+OO9TL3tXFCQa+dJKGHL3QNQdrsiKJZpJuNRG0VG4VInJ+/IPt4EyU5dFeQje oD94/juodPIgwr0nMXgc7iv8B1rImG7/AZrJKlQnfqv3hffIVwYoE59X8Mi64ns5cA0X Unkw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id a1si2509031edv.245.2020.07.23.13.10.10; Thu, 23 Jul 2020 13:10:33 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726870AbgGWUHS (ORCPT + 99 others); Thu, 23 Jul 2020 16:07:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725894AbgGWUHS (ORCPT ); Thu, 23 Jul 2020 16:07:18 -0400 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D096EC0619DC; Thu, 23 Jul 2020 13:07:17 -0700 (PDT) Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.93) (envelope-from ) id 1jyhUc-009mYg-5X; Thu, 23 Jul 2020 22:07:02 +0200 Message-ID: Subject: Re: [RFC 1/7] mac80211: Add check for napi handle before WARN_ON From: Johannes Berg To: Rakesh Pillai , ath10k@lists.infradead.org Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, kvalo@codeaurora.org, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, dianders@chromium.org, evgreen@chromium.org Date: Thu, 23 Jul 2020 22:06:46 +0200 In-Reply-To: <003201d6611e$c54a1c90$4fde55b0$@codeaurora.org> References: <1595351666-28193-1-git-send-email-pillair@codeaurora.org> <1595351666-28193-2-git-send-email-pillair@codeaurora.org> <0dbdef912f9d61521011f638200fd451a3530568.camel@sipsolutions.net> <003201d6611e$c54a1c90$4fde55b0$@codeaurora.org> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.3 (3.36.3-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2020-07-23 at 23:56 +0530, Rakesh Pillai wrote: > > > - WARN_ON_ONCE(softirq_count() == 0); > > > + WARN_ON_ONCE(napi && softirq_count() == 0); > > > > FWIW, I'm pretty sure this is incorrect - we make assumptions on > > softirqs being disabled in mac80211 for serialization and in place of > > some locking, I believe. > > > > I checked this, but let me double confirm. > But after this change, no packet is submitted from driver in a softirq context. > So ideally this should take care of serialization. I'd guess that we have some reliance on BHs already being disabled, for things like u64 sync updates, or whatnot. I mean, we did "rx_ni()" for a reason ... Maybe lockdep can help catch some of the issues. But couldn't you be in a thread and have BHs disabled too? johannes