From nobody Sat Nov 1 10:17:26 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1582540509; cv=none; d=zohomail.com; s=zohoarc; b=A7l+Z8f2M0wQKIoP+rWi9vgGPk+uZurxXQoS+EqySuKp9Ixxu+u23MJQda+2WfMWwN/HVQY3n8yQDcDjc7QbNL2GKXpUQ7CU7BBE4ppvdgMw9ogXRDkQPIExM3uTE0tWdYx+K0e4hSU/6oCass+UyCdTbXivCg6MRQTLDmuYR1I= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1582540509; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=6DuJZhufpf0aFOVc/6GZove5MAyebHMgmt+bclbTTvM=; b=ffqUAKLRC+bI6s+QIdvM/1BE/IxybazO0vEub24jx1wRyJ/8DLpZzaa+XpzgQgAYfaCRfqNvXt9cKXYfmb+/IuWDSmdJoGlAKBOu51yurLAN8EOLYcBRivU1ywq0nNvKuWOKhoOcfvrlkE8IzKD819ETk7GKxp4O4Q6q1faISag= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1582540509533170.16283645664987; Mon, 24 Feb 2020 02:35:09 -0800 (PST) Received: from localhost ([::1]:34432 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6B4t-0001PO-Gh for importer@patchew.org; Mon, 24 Feb 2020 05:35:07 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:44057) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6B4A-0000O1-5t for qemu-devel@nongnu.org; Mon, 24 Feb 2020 05:34:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6B48-0007l0-V9 for qemu-devel@nongnu.org; Mon, 24 Feb 2020 05:34:22 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:52297 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j6B48-0007kl-Ri for qemu-devel@nongnu.org; Mon, 24 Feb 2020 05:34:20 -0500 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-148-KJx8PHpxNPWNMHVN8cecqg-1; Mon, 24 Feb 2020 05:34:16 -0500 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 A4934800D5A; Mon, 24 Feb 2020 10:34:15 +0000 (UTC) Received: from localhost (unknown [10.36.118.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9552A27081; Mon, 24 Feb 2020 10:34:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582540460; 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: in-reply-to:in-reply-to:references:references; bh=6DuJZhufpf0aFOVc/6GZove5MAyebHMgmt+bclbTTvM=; b=KwYpSGHgeMOi0DCyQdRfqt1232ZLa1XNc9C6TgUTlGlBZlQAS8JpMnXa+QgGPoDqhV8pdr utxm3XCmu+4Ka4s0Tkp+mC2mJhQx7r243RqSufixq11Ya40mJZHT+6LK812ODXiYc22wwP ayM1O0274Yx52nHkfwjmZImQAAmlFek= X-MC-Unique: KJx8PHpxNPWNMHVN8cecqg-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 1/2] qemu/queue.h: clear linked list pointers on remove Date: Mon, 24 Feb 2020 10:34:05 +0000 Message-Id: <20200224103406.1894923-2-stefanha@redhat.com> In-Reply-To: <20200224103406.1894923-1-stefanha@redhat.com> References: <20200224103406.1894923-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 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: Fam Zheng , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Do not leave stale linked list pointers around after removal. It's safer to set them to NULL so that use-after-removal results in an immediate segfault. The RCU queue removal macros are unchanged since nodes may still be traversed after removal. Suggested-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- include/qemu/queue.h | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/include/qemu/queue.h b/include/qemu/queue.h index 294db54eb1..456a5b01ee 100644 --- a/include/qemu/queue.h +++ b/include/qemu/queue.h @@ -142,6 +142,8 @@ struct { = \ (elm)->field.le_next->field.le_prev =3D \ (elm)->field.le_prev; \ *(elm)->field.le_prev =3D (elm)->field.le_next; \ + (elm)->field.le_next =3D NULL; \ + (elm)->field.le_prev =3D NULL; \ } while (/*CONSTCOND*/0) =20 /* @@ -225,12 +227,15 @@ struct { = \ } while (/*CONSTCOND*/0) =20 #define QSLIST_REMOVE_HEAD(head, field) do { \ - (head)->slh_first =3D (head)->slh_first->field.sle_next; \ + typeof((head)->slh_first) elm =3D (head)->slh_first; = \ + (head)->slh_first =3D elm->field.sle_next; = \ + elm->field.sle_next =3D NULL; = \ } while (/*CONSTCOND*/0) =20 #define QSLIST_REMOVE_AFTER(slistelm, field) do { \ - (slistelm)->field.sle_next =3D \ - QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field); \ + typeof(slistelm) next =3D (slistelm)->field.sle_next; \ + (slistelm)->field.sle_next =3D next->field.sle_next; \ + next->field.sle_next =3D NULL; \ } while (/*CONSTCOND*/0) =20 #define QSLIST_REMOVE(head, elm, type, field) do { \ @@ -241,6 +246,7 @@ struct { = \ while (curelm->field.sle_next !=3D (elm)) \ curelm =3D curelm->field.sle_next; \ curelm->field.sle_next =3D curelm->field.sle_next->field.sle_next;= \ + (elm)->field.sle_next =3D NULL; \ } \ } while (/*CONSTCOND*/0) =20 @@ -304,8 +310,10 @@ struct { = \ } while (/*CONSTCOND*/0) =20 #define QSIMPLEQ_REMOVE_HEAD(head, field) do { \ - if (((head)->sqh_first =3D (head)->sqh_first->field.sqe_next) =3D=3D N= ULL)\ + typeof((head)->sqh_first) elm =3D (head)->sqh_first; \ + if (((head)->sqh_first =3D elm->field.sqe_next) =3D=3D NULL) = \ (head)->sqh_last =3D &(head)->sqh_first; \ + elm->field.sqe_next =3D NULL; \ } while (/*CONSTCOND*/0) =20 #define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do { \ @@ -329,6 +337,7 @@ struct { = \ if ((curelm->field.sqe_next =3D \ curelm->field.sqe_next->field.sqe_next) =3D=3D NULL) = \ (head)->sqh_last =3D &(curelm)->field.sqe_next; \ + (elm)->field.sqe_next =3D NULL; \ } \ } while (/*CONSTCOND*/0) =20 @@ -446,6 +455,8 @@ union { = \ (head)->tqh_circ.tql_prev =3D (elm)->field.tqe_circ.tql_prev; \ (elm)->field.tqe_circ.tql_prev->tql_next =3D (elm)->field.tqe_next= ; \ (elm)->field.tqe_circ.tql_prev =3D NULL; \ + (elm)->field.tqe_circ.tql_next =3D NULL; \ + (elm)->field.tqe_next =3D NULL; \ } while (/*CONSTCOND*/0) =20 /* remove @left, @right and all elements in between from @head */ --=20 2.24.1 From nobody Sat Nov 1 10:17:26 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; 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Mon, 24 Feb 2020 05:34:21 -0500 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 6CAB7800D5B; Mon, 24 Feb 2020 10:34:20 +0000 (UTC) Received: from localhost (unknown [10.36.118.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CA8B91851; Mon, 24 Feb 2020 10:34:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582540463; 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: in-reply-to:in-reply-to:references:references; bh=TUBsFZa5Km+NRvGWPPSzT5mjOSKWnAkAeFx7tI26nEM=; b=SqDISD8TzS5fRtFNjTqZ6+J1J42CGArYSMPJgISN3PYjXxbjk1j1EjSnw+NQ0cLoam3oBf 0+27XdAuYnvPTA7syc5AKMX0lNSvqHomH8WADPGmBvXXIUn8Y7X2PS8b7wKWEfT/SZViHF x/fM5qj90wdnIxFmtvrQexns/SVPwJQ= X-MC-Unique: FXvQdUtIOuian3xrOq9dCQ-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 2/2] aio-posix: remove confusing QLIST_SAFE_REMOVE() Date: Mon, 24 Feb 2020 10:34:06 +0000 Message-Id: <20200224103406.1894923-3-stefanha@redhat.com> In-Reply-To: <20200224103406.1894923-1-stefanha@redhat.com> References: <20200224103406.1894923-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: Fam Zheng , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" QLIST_SAFE_REMOVE() is confusing here because the node must be on the list. We actually just wanted to clear the linked list pointers when removing it from the list. QLIST_REMOVE() now does this, so switch to it. Suggested-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- util/aio-posix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/util/aio-posix.c b/util/aio-posix.c index 7e6c9835bb..026c1f5286 100644 --- a/util/aio-posix.c +++ b/util/aio-posix.c @@ -493,7 +493,7 @@ static bool aio_dispatch_ready_handlers(AioContext *ctx, AioHandler *node; =20 while ((node =3D QLIST_FIRST(ready_list))) { - QLIST_SAFE_REMOVE(node, node_ready); + QLIST_REMOVE(node, node_ready); progress =3D aio_dispatch_handler(ctx, node) || progress; } =20 --=20 2.24.1