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 DE28EC433EF for ; Tue, 26 Oct 2021 14:12:37 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 85A426103C for ; Tue, 26 Oct 2021 14:12:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 85A426103C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:55238 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mfNBs-0005xI-Jb for qemu-devel@archiver.kernel.org; Tue, 26 Oct 2021 10:12:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47134) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mfN9u-0004af-01 for qemu-devel@nongnu.org; Tue, 26 Oct 2021 10:10:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:28912) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mfN9p-0007h4-Ok for qemu-devel@nongnu.org; Tue, 26 Oct 2021 10:10:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635257428; 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=5LXaiVrYgB1eG2aJ7cjmqV1mzz6fPRbnM2eMys9EPhM=; b=JPDqKZWmbJPTKiOcYfjNYBzJX5KcuYE7Z62/V/M5A6Hv33Zfj/K9BB5QQ/FvrEaxLqghGo 4+GBQGeQoLuFrU/jN3kEG3F5PSZ5S81pIwi0Lo7qOI4WHVSnnBofrLDakrSKcGuFN5GT9k IKqAIFBnzP219dtP2TzS2vt3Y5qKM6c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-16-1Ji2bZFOMDK2EgJ9mau0YQ-1; Tue, 26 Oct 2021 10:10:24 -0400 X-MC-Unique: 1Ji2bZFOMDK2EgJ9mau0YQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C24D580DDE1; Tue, 26 Oct 2021 14:10:23 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.70]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0E8CF5F4EB; Tue, 26 Oct 2021 14:10:17 +0000 (UTC) Date: Tue, 26 Oct 2021 16:10:16 +0200 From: Kevin Wolf To: Stefan Hajnoczi Subject: Re: [RFC 1/2] tls: add macros for coroutine-safe TLS variables Message-ID: References: <20211025140716.166971-1-stefanha@redhat.com> <20211025140716.166971-2-stefanha@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="MBaMJdUkSw0XWWci" Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fweimer@redhat.com, Fam Zheng , thuth@redhat.com, Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , qemu-block@nongnu.org, qemu-devel@nongnu.org, sguelton@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --MBaMJdUkSw0XWWci Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Am 26.10.2021 um 15:41 hat Stefan Hajnoczi geschrieben: > Actually, nevermind what I said about the callback scenario. I don't > think that is a problem because the compiler cannot assume the __thread > variable remains unchanged across the callback. Therefore it cannot > safely cache the value. And additionally, I think callbacks are never coroutine_fn (especially not if they come from an external library), so they must not yield anyway. > So I think only the header file scenario is a problem. The mere existence of a __thread variable in the header file isn't a problem either, but if QEMU accesses it, we would have to implement wrappers similar to what you're proposing for QEMU's thread local variables. Kevin --MBaMJdUkSw0XWWci Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE3D3rFZqa+V09dFb+fwmycsiPL9YFAmF4DEgACgkQfwmycsiP L9Z8hQ//XubbHmIJZr0Cxgr+XIYq4W1oAD+mFnhBYU2hL69gFLJu5tTbkdsmIpOU kL/JTfyaoJUoqnaF5RCuR7N/Mf/WBJcLc7cRFO3vG34QZdimqDrIF0LYgiv1Fx3+ VOY/6TY46m5SIHjt/P9fdBxMmH3cO222xGeELUW655ZYg2fQODnW0rL2DVunD5+b NuqjfGhly2Ut3FSNqqKjkMWncakX6cl1nYI+v1CaaU8klsmw8NpZ705E4XIwyIOe 4OwxzsTFz6A5qKfm9BwjuZmwNP/Sd9RVkzrl/iLFE55SRALgF8LEgMxHSBkiFvdN bbnYpIis40XhKVaOoh6dyRuTQg8UUGXgp8afLoaFqSAfIRSVEIjd8qmE1y9683AZ L/HbI0jdOGyNlfOUHrpJBt8GtAxLEwCsaZyg/ksavCNteB9GFWUqaD7ge8G0kHQB qI9g3a0zW8921nlltx/XLZeIAw6aM5O2/axkAsOdCWp8xXPSx3OgQvx2NkehYNps gpen23+7w8a1nC2uyXbMwUPEoR7C42p7mXUL071vNqfP3By+2/MJq68vDHj5wIT1 WOmGc2kPiEmycZ/FdUly21sJ9dV8PNFunhjyLtfMiOHJni5umLIOfB1b1GfXEIPc kuHw4PgXEzg9nWNt0Jn/tlEJCbto6iluoMuJRqQrH9+zEHC9KSM= =lnpP -----END PGP SIGNATURE----- --MBaMJdUkSw0XWWci--