From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07964C2BA1E for ; Mon, 6 Apr 2020 13:05:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD32E22273 for ; Mon, 6 Apr 2020 13:05:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="dtnxVPkw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728297AbgDFNFL (ORCPT ); Mon, 6 Apr 2020 09:05:11 -0400 Received: from mail26.static.mailgun.info ([104.130.122.26]:14098 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728061AbgDFNFL (ORCPT ); Mon, 6 Apr 2020 09:05:11 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1586178310; h=Content-Type: MIME-Version: Message-ID: In-Reply-To: Date: References: Subject: Cc: To: From: Sender; bh=TXoCw5GkV+IZIhQrsD2drq5aTCEc6Wa8f+KDKz8AGtc=; b=dtnxVPkwVJjKFkWX4shE4wtLFGEjxEgfPdVavuvK2t2jd90HBkqheB/3Gt3GQjh0um3LwHgk 90rNrTa9zjpORzMcYUTQ01aX7ftIDpBLwTznvpR/CbnrumNoKo7RKg/xv53Gje1GFeu7Qse2 APhIT4RCRDDldEnciMTE3eCrGuI= X-Mailgun-Sending-Ip: 104.130.122.26 X-Mailgun-Sid: WyI3YTAwOSIsICJsaW51eC13aXJlbGVzc0B2Z2VyLmtlcm5lbC5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e8b28ff.7f7f4c9a95e0-smtp-out-n01; Mon, 06 Apr 2020 13:05:03 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 64193C43637; Mon, 6 Apr 2020 13:05:03 +0000 (UTC) Received: from potku.adurom.net (88-114-240-156.elisa-laajakaista.fi [88.114.240.156]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: kvalo) by smtp.codeaurora.org (Postfix) with ESMTPSA id A0849C433D2; Mon, 6 Apr 2020 13:04:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org A0849C433D2 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=kvalo@codeaurora.org From: Kalle Valo To: Johannes Berg Cc: Sumit Garg , linux-wireless@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, matthias.schoepfer@ithinx.io, Philipp.Berg@liebherr.com, Michael.Weitner@liebherr.com, daniel.thompson@linaro.org, loic.poulain@linaro.org, stable@vger.kernel.org Subject: Re: [PATCH] mac80211: fix race in ieee80211_register_hw() References: <1586175677-3061-1-git-send-email-sumit.garg@linaro.org> <87ftdgokao.fsf@tynnyri.adurom.net> <1e352e2130e19aec5aa5fc42db397ad50bb4ad05.camel@sipsolutions.net> <87r1x0zsgk.fsf@kamboji.qca.qualcomm.com> Date: Mon, 06 Apr 2020 16:04:57 +0300 In-Reply-To: (Johannes Berg's message of "Mon, 06 Apr 2020 14:53:49 +0200") Message-ID: <87imiczrwm.fsf@kamboji.qca.qualcomm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Johannes Berg writes: > On Mon, 2020-04-06 at 15:52 +0300, Kalle Valo wrote: >> Johannes Berg writes: >> >> > On Mon, 2020-04-06 at 15:44 +0300, Kalle Valo wrote: >> > > > user-space ieee80211_register_hw() RX IRQ >> > > > +++++++++++++++++++++++++++++++++++++++++++++ >> > > > | | | >> > > > |<---wlan0---wiphy_register() | >> > > > |----start wlan0---->| | >> > > > | |<---IRQ---(RX packet) >> > > > | Kernel crash | >> > > > | due to unallocated | >> > > > | workqueue. | >> > >> > [snip] >> > >> > > I have understood that no frames should be received until mac80211 calls >> > > struct ieee80211_ops::start: >> > > >> > > * @start: Called before the first netdevice attached to the hardware >> > > * is enabled. This should turn on the hardware and must turn on >> > > * frame reception (for possibly enabled monitor interfaces.) >> > >> > True, but I think he's saying that you can actually add and configure an >> > interface as soon as the wiphy is registered? >> >> With '<---IRQ---(RX packet)' I assumed wcn36xx is delivering a frame to >> mac80211 using ieee80211_rx(), but of course I'm just guessing here. > > Yeah, but that could be legitimate? Ah, I misunderstood then. The way I have understood is that no rx frames should be delivered (= calling ieee80211_rx()_ before start() is called, but if that's not the case please ignore me :) -- https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches