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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 006EEC43387 for ; Thu, 3 Jan 2019 16:08:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB8CF217D9 for ; Thu, 3 Jan 2019 16:08:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732007AbfACQIW (ORCPT ); Thu, 3 Jan 2019 11:08:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:61719 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730146AbfACQIR (ORCPT ); Thu, 3 Jan 2019 11:08:17 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 42F223E2D0; Thu, 3 Jan 2019 16:08:17 +0000 (UTC) Received: from localhost (dhcp-192-187.str.redhat.com [10.33.192.187]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D7E085C1B2; Thu, 3 Jan 2019 16:08:16 +0000 (UTC) From: Cornelia Huck To: "Michael S . Tsirkin" , Jason Wang Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, virtio-dev@lists.oasis-open.org, Wei Wang , Halil Pasic , Cornelia Huck Subject: [PATCH 2/2] virtio: document virtio_config_ops restrictions Date: Thu, 3 Jan 2019 17:08:04 +0100 Message-Id: <20190103160804.21438-3-cohuck@redhat.com> In-Reply-To: <20190103160804.21438-1-cohuck@redhat.com> References: <20190103160804.21438-1-cohuck@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 03 Jan 2019 16:08:17 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some transports (e.g. virtio-ccw) implement virtio operations that seem to be a simple read/write as something more involved that cannot be done from an atomic context. Give at least a hint about that. Signed-off-by: Cornelia Huck --- include/linux/virtio_config.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index 7087ef946ba7..987b6491b946 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -12,6 +12,11 @@ struct irq_affinity; /** * virtio_config_ops - operations for configuring a virtio device + * Note: Do not assume that a transport implements all of the operations + * getting/setting a value as a simple read/write! Generally speaking, + * any of @get/@set, @get_status/@set_status, or @get_features/ + * @finalize_features are NOT safe to be called from an atomic + * context. * @get: read the value of a configuration field * vdev: the virtio_device * offset: the offset of the configuration field -- 2.17.2