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 857F9C433EF for ; Fri, 14 Jan 2022 21:57:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230006AbiANV5c (ORCPT ); Fri, 14 Jan 2022 16:57:32 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:46675 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230001AbiANV5b (ORCPT ); Fri, 14 Jan 2022 16:57:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642197449; 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=L16b4DGvxyPb5nATXEM8DIgZjgXdywlPz0ryK6DeeCM=; b=BkjCaRmIUO636ZPtGKt18sGd8GVMVbAzKVbqf7Np5vcQsamgX8keP+NDi/ZeNgcbzefeTU 83hCa5f+AY0J2v/Az1N3USl2pNTLjfXs/Gmy9oPNOHLhxzj73UBpyNtrSoD81ANesWfVbR /swPwKlYZUyxfZRv7cDK1oARChBzkMg= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-439-cSLt-ZQ_M_SZfTI4Lc569g-1; Fri, 14 Jan 2022 16:57:28 -0500 X-MC-Unique: cSLt-ZQ_M_SZfTI4Lc569g-1 Received: by mail-ed1-f70.google.com with SMTP id z10-20020a05640235ca00b003f8efab3342so9313144edc.2 for ; Fri, 14 Jan 2022 13:57:28 -0800 (PST) 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=L16b4DGvxyPb5nATXEM8DIgZjgXdywlPz0ryK6DeeCM=; b=opk8HRqnuhBthmgndoDiuJ0o1KNVkWd++mdXoQFfxGOAomibbBZM5fD3NfJnL15oKg /O2i+CISI3A4rvHe3pr37bHaRjy1WgqTX8655a4DMXGCZPjx5yRWh69whTxsTpvmGxfW gtJeHxcxK2P2jFCeOpFJvS7GXxm6ByNNvOl8HuRmAyn5ToAJPXHrjbaPkasg3BFRvEOU t2GvVWemHjne9Th/cuO9EXWiGL51eug57ojy/vf/F09QBK78fw/9804H8ddExSmY6LGH r8ozoyrPEXhHWOs2g+ugVspuvBWan/OiLMZykrLS3ZfGZtDyNHhlMYbyUDOPgz2hcH7d lHPQ== X-Gm-Message-State: AOAM530iiWrA8qvX4zkDfcWLnK34HMIH5WVc32yRufQtCT2zsJkdRI5J emMAaSK7OyeEEUb8DZ8BpHlUag0syb4ALPWo3lXn1jsuu1g4kT8Inqw8rS83K8BduN2vl7ZvMvj MtMJFKFiRSfjBw1o94IAi3eoLFFhR/tpDggksI4QxsLtLaSnyVeiMNnqElJY4dP/ynLq9jA== X-Received: by 2002:aa7:ce14:: with SMTP id d20mr8882139edv.234.1642197447022; Fri, 14 Jan 2022 13:57:27 -0800 (PST) X-Google-Smtp-Source: ABdhPJzRf2UPE1rQiu4oDrmGOKJ5fch7iHEHP3P6A+VJ1Pk64gSLJydxmVYQaT6KOfiVjxBzt05taw== X-Received: by 2002:aa7:ce14:: with SMTP id d20mr8882118edv.234.1642197446731; Fri, 14 Jan 2022 13:57:26 -0800 (PST) Received: from redhat.com ([2.55.154.210]) by smtp.gmail.com with ESMTPSA id c12sm2869794edx.80.2022.01.14.13.57.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Jan 2022 13:57:25 -0800 (PST) Date: Fri, 14 Jan 2022 16:57:24 -0500 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Jason Wang , virtualization@lists.linux-foundation.org Subject: [PATCH v2 1/3] virtio: document virtio_reset_device Message-ID: <20220114215641.239984-2-mst@redhat.com> References: <20220114215641.239984-1-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220114215641.239984-1-mst@redhat.com> X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Looks like most callers get driver/device removal wrong. Document what's expected of callers. Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index 2ed6e2451fd8..631a346a3aa6 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -201,6 +201,22 @@ static int virtio_finalize_features(struct virtio_device *dev) return 0; } +/** + * virtio_reset_device - quiesce device for removal + * @dev: the device to reset + * + * Prevents device from sending interrupts and accessing memory. + * + * Generally used for cleanup during driver / device removal. + * + * Once this has been invoked, caller must ensure that + * virtqueue_notify / virtqueue_kick are not in progress. + * + * Note: this guarantees that vq callbacks are not in progress, however caller + * is responsible for preventing access from other contexts, such as a system + * call/workqueue/bh. Invoking virtio_break_device then flushing any such + * contexts is one way to handle that. + * */ void virtio_reset_device(struct virtio_device *dev) { dev->config->reset(dev); -- MST