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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EC39C43334 for ; Tue, 28 Jun 2022 16:30:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236297AbiF1Qac (ORCPT ); Tue, 28 Jun 2022 12:30:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348441AbiF1Q3s (ORCPT ); Tue, 28 Jun 2022 12:29:48 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4C2BD3AA7B for ; Tue, 28 Jun 2022 09:21:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1656433286; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1k3CBwOlDNKLLgVJWLqKeFaKpZTZnO4zAu76Qx9GG0o=; b=T6SUE3v/UmAusFMCs/XvzNt4AwfIQypqqoPAeajwWcziDRZIp5QnB4wnUIRexk7BNFsWGy HxC0IeJtn0UeVDLsZbrfeRqWIYHKz0asRIbEtoP0TCkCjkQa/J4sFufTA4Zuv6jMtjtMqZ Hup7rQqwDP85jBAzoI7gVaZuZYifl0U= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-404-hYBgwwC3MfCK5XBENf_F7w-1; Tue, 28 Jun 2022 12:21:25 -0400 X-MC-Unique: hYBgwwC3MfCK5XBENf_F7w-1 Received: by mail-wm1-f69.google.com with SMTP id e24-20020a05600c219800b003a0471b1904so4120735wme.1 for ; Tue, 28 Jun 2022 09:21:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=1k3CBwOlDNKLLgVJWLqKeFaKpZTZnO4zAu76Qx9GG0o=; b=TEwoUq6P54PErQr4ogIwZuRG1yJHisyq7Yq63jrBtlD8tl7XYGLQy8C9peELkAvYMU lkGFlAMSFTWPVjJ8Ii8anWe7UvrNajU20YVJl5YgguWTUd6YUfdrI3Yw/iV0Tx1Y/37d krC9v6H6K3rUM+IfrvsLkFm0qE0Ob97tbbUGHWDEMsCnxAzlp5UhqZaQz2L9cgVtqujM axiBWCTMlPssw6FE8bGcmFTgulm/CW5LTggOYlTjDbC87+m9sqKNOVx46jB+ULPqxegE YHcAZQU+9lBzExAO+GJEleXiW17FxdZOzphGQrRhf8aUglda60c5yNAK0WGXiJkBGs0m y9vQ== X-Gm-Message-State: AJIora+NrAVGaPrTlN3DMo32LWabg1vxlrKUuJw1PNtGqYhNdBUKYz4z OSfTN9GsamZh2rD0CVjl3NdWP6QIe2lppsSVdmLhhIgQLTnX/FiQwpKP+M+goOcZp4flzFY+ypr EG4iZoqS1SEspAB5iLipJt7xf X-Received: by 2002:a05:6000:168b:b0:21b:a2c1:c93d with SMTP id y11-20020a056000168b00b0021ba2c1c93dmr19798235wrd.358.1656433283821; Tue, 28 Jun 2022 09:21:23 -0700 (PDT) X-Google-Smtp-Source: AGRyM1uu+nFvJHR79Zm6a20l826vX97rS7XFvJDCMz5epAWBPHZ04E38/KxhS9TcdigmR+mZjbPDqg== X-Received: by 2002:a05:6000:168b:b0:21b:a2c1:c93d with SMTP id y11-20020a056000168b00b0021ba2c1c93dmr19798215wrd.358.1656433283636; Tue, 28 Jun 2022 09:21:23 -0700 (PDT) Received: from localhost (cpc111743-lutn13-2-0-cust979.9-3.cable.virginm.net. [82.17.115.212]) by smtp.gmail.com with ESMTPSA id a17-20020adffb91000000b0020c5253d907sm14249763wrr.83.2022.06.28.09.21.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jun 2022 09:21:22 -0700 (PDT) Date: Tue, 28 Jun 2022 17:21:22 +0100 From: Aaron Tomlin To: Steven Rostedt Cc: mcgrof@kernel.org, christophe.leroy@csgroup.eu, cl@linux.com, mbenes@suse.cz, akpm@linux-foundation.org, jeyu@kernel.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, void@manifault.com, atomlin@atomlin.com, allen.lkml@gmail.com, joe@perches.com, msuchanek@suse.de, oleksandr@natalenko.name, jason.wessel@windriver.com, pmladek@suse.com, neelx@redhat.com, daniel.thompson@linaro.org, hch@infradead.org, Thomas Gleixner , linux-rt-users Subject: Re: [PATCH v11 10/14] module: kallsyms: Fix suspicious rcu usage Message-ID: <20220628162122.v7s3z24icwavur6y@ava.usersys.com> X-PGP-Key: http://pgp.mit.edu/pks/lookup?search=atomlin%40redhat.com X-PGP-Fingerprint: 7906 84EB FA8A 9638 8D1E 6E9B E2DE 9658 19CC 77D6 References: <20220310102413.3438665-1-atomlin@redhat.com> <20220310102413.3438665-11-atomlin@redhat.com> <20220627235612.4796c837@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220627235612.4796c837@gandalf.local.home> Precedence: bulk List-ID: On Mon 2022-06-27 23:56 -0400, Steven Rostedt wrote: > > + preempt_enable(); > > ^^^^^^^^^^^^^^^^^ > > This just introduced an unbounded latency and will fail PREEMPT_RT. > Hi Steve, Sorry about that! If I understand correctly, there is absolutely no need to explicitly disable preemption in this context. I will use: rcu_read_lock() and rcu_read_unlock(), respectively, which will then be suitable for the preemptible RCU implementation. Kind regards, -- Aaron Tomlin