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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 25330C4332F for ; Mon, 27 Sep 2021 14:20:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B80760EC0 for ; Mon, 27 Sep 2021 14:20:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234761AbhI0OWd (ORCPT ); Mon, 27 Sep 2021 10:22:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234690AbhI0OW2 (ORCPT ); Mon, 27 Sep 2021 10:22:28 -0400 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6262DC061575; Mon, 27 Sep 2021 07:20:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=eOvgrhpxN9OxQ688askyKJoBpK1KwuAfg2w4kS25LTE=; t=1632752450; x=1633962050; b=yAeCSf0QyuInxUdse30wxb5qVa3dWzONJpzq54xaxEoU/8m UxxPeD1e8WVAcmeR6hBG9eiGd8giJ+VAh2MJQSLlK4SpVspxx2i9lIhJNbYX8tjRmGVam+IpHb4GL 64C3d+VHIKNIOHPVpwzq8aTr0V54nKtjUL0AVmnhm/PTDpgKY+A46WOFbIoOTS6gkcYgyUdJ6Wh8Q M7jIHKMfZpt+rseyKHkx1+SwA0MszKMlHFdLSmwhUVPzNww1Jj1Barlji7wC7oWybrBHDSSu5EVuD hm4bDM3pDCWCuE+LosH8emZ7olsVg0oTlx9mL4/sqwaLPggodd3UX9Fnw2vvZL6A==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.95-RC2) (envelope-from ) id 1mUrUt-00CSGB-SC; Mon, 27 Sep 2021 16:20:47 +0200 Message-ID: <97300681a8e793b71ccedf8224010f1f64da6b5c.camel@sipsolutions.net> Subject: Re: [PATCH] leds: trigger: use RCU to protect the led_cdevs list From: Johannes Berg To: Pavel Machek Cc: linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Date: Mon, 27 Sep 2021 16:20:47 +0200 In-Reply-To: <20210927141619.GA18276@duo.ucw.cz> References: <20210915181601.99a68f5718be.I1a28b342d2d52cdeeeb81ecd6020c25cbf1dbfc0@changeid> <20210927141619.GA18276@duo.ucw.cz> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-malware-bazaar: not-scanned Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pavel, > > > > Cc: stable@vger.kernel.org > > I ... don't like idea of this going to stable. OK, I guess that's fair. We've been running into the lockdep report for a while - ever since we made the spinlock in iwlwifi no longer disable IRQs all the time, which was meant to be a good thing ... However, the scenario that could cause *real* deadlocks there is really unlikely and requires four CPUs all doing the exactly right thing, including a normally very rare *write lock* on the leddev_list_lock, so I don't think in practice it'll be much of an issue. johannes