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 D6CF7C433EF for ; Mon, 25 Oct 2021 14:09:54 +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 8FCA960F70 for ; Mon, 25 Oct 2021 14:09:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8FCA960F70 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]:34502 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mf0fh-000099-KX for qemu-devel@archiver.kernel.org; Mon, 25 Oct 2021 10:09:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53878) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mf0de-0004cJ-Ly for qemu-devel@nongnu.org; Mon, 25 Oct 2021 10:07:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:37675) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mf0dc-0005vA-RN for qemu-devel@nongnu.org; Mon, 25 Oct 2021 10:07:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635170864; 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: content-transfer-encoding:content-transfer-encoding; bh=8erAyC6VVUD5BfIdlIquvBBvcuoZlRJKReRhticBUKs=; b=FaAdV3lP6I1qKzXYt40SZ7qtYf2DZDQwzppYxIXzTQFiTCNwmztDU/VhTf6cq/oBslLMAH M2xDS2aSyf4YUnS/l5R4V6Uykz5qZGTsZ4uSe4hxC1qi9L756XNjcKp1KQGRy5m9y+oRhF yyeV24bWlU7m9EifzH894OowKdVGuq0= 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-398-LsauKrBTNNevuJKiw5155Q-1; Mon, 25 Oct 2021 10:07:41 -0400 X-MC-Unique: LsauKrBTNNevuJKiw5155Q-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F3FE38018AC; Mon, 25 Oct 2021 14:07:39 +0000 (UTC) Received: from localhost (unknown [10.39.192.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id C99BD19D9D; Mon, 25 Oct 2021 14:07:17 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [RFC 0/2] tls: add macros for coroutine-safe TLS variables Date: Mon, 25 Oct 2021 15:07:14 +0100 Message-Id: <20211025140716.166971-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@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=ham 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, Kevin Wolf , thuth@redhat.com, qemu-block@nongnu.org, Stefan Hajnoczi , Fam Zheng , sguelton@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is a preview of how we can solve the coroutines TLS problem. Coroutine= s=0D re-entered from another thread sometimes see stale TLS values. This happens= =0D because compilers may cache values across yield points, so a value from the= =0D previous thread will be used when the coroutine is re-entered in another=0D thread.=0D =0D Serge Guelton developed this technique, see the first patch for details. I'= m=0D submitting it for discussion before I go ahead with a full conversion of th= e=0D source tree.=0D =0D Todo:=0D - Convert all uses of __thread=0D - Extend checkpatch.pl to reject code that uses __thread=0D =0D Stefan Hajnoczi (2):=0D tls: add macros for coroutine-safe TLS variables=0D util/async: replace __thread with QEMU TLS macros=0D =0D MAINTAINERS | 1 +=0D include/qemu/tls.h | 142 +++++++++++++++++++++++++++++++++++++++++++++=0D util/async.c | 12 ++--=0D 3 files changed, 150 insertions(+), 5 deletions(-)=0D create mode 100644 include/qemu/tls.h=0D =0D --=20=0D 2.31.1=0D =0D