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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 629EBCA0EDC for ; Wed, 20 Aug 2025 06:47:10 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uocae-0004vw-RG; Wed, 20 Aug 2025 02:46:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uocab-0004vm-S9 for qemu-devel@nongnu.org; Wed, 20 Aug 2025 02:46:29 -0400 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uocaX-0005FN-Sd for qemu-devel@nongnu.org; Wed, 20 Aug 2025 02:46:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=XwEI5aI1pHHIdibANKF91uzO8DnB8wrZDrMYN4JK6E4=; b=ph0qH1aMxBVnN99N3m5cpryebE VlSZyoRQMFuitdIUUpuMm6zJ4PwU1r8u7BSCZGpbxcClrSoAKtjA4avro0TNW4L59txBhtp4sRrcD mgx/GCU7VDlkvXdFftBCF2aX7150nhtPg6sKheuKCPoeoX5q/aUxNR0hstBLOK/mwPKELLXpDWxMU 8RlUBac87hS1riIhjAoq7NgZ5LqMrITkTHraI/AicRy8pghDfhArgNaNtOyw4z1SP73YNfNlSMuBH RCPx6n9JYU7gsou5bEL/15d04b3CA17Gh+BU8VdATKwyqSW1wuGntfM3BUcUh98q/G21VtXS2cL6A 7A7eg6vQ==; Received: from 54-240-197-234.amazon.com ([54.240.197.234] helo=freeip.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uocaN-00000001zbn-1Tfs; Wed, 20 Aug 2025 06:46:16 +0000 Message-ID: Subject: Re: [PULL 2/5] net: move backend cleanup to NIC cleanup From: David Woodhouse To: Jason Wang , Eugenio =?ISO-8859-1?Q?P=E9rez?= , Jonah Palmer Cc: qemu-devel@nongnu.org, Lei Yang Date: Wed, 20 Aug 2025 07:46:15 +0100 In-Reply-To: References: <20250310122240.2908-1-jasowang@redhat.com> <20250310122240.2908-3-jasowang@redhat.com> <29e31b2d06036441ede4ccb2d2bd22a6c1ba33ae.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-NXmT5LYMnmniAtV3i3O8" User-Agent: Evolution 3.52.3-0ubuntu1 MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: none client-ip=2001:8b0:10b:1236::1; envelope-from=BATV+d6f0842bcde9a785871d+8032+infradead.org+dwmw2@casper.srs.infradead.org; helo=casper.infradead.org X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --=-NXmT5LYMnmniAtV3i3O8 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2025-08-20 at 10:34 +0800, Jason Wang wrote: > On Wed, Aug 20, 2025 at 12:13=E2=80=AFAM David Woodhouse wrote: > >=20 > > On Mon, 2025-03-10 at 20:22 +0800, Jason Wang wrote: > > > From: Eugenio P=C3=A9rez > > >=20 > > > Commit a0d7215e33 ("vhost-vdpa: do not cleanup the vdpa/vhost-net > > > structures if peer nic is present") effectively delayed the backend > > > cleanup, allowing the frontend or the guest to access it resources as > > > long as the frontend is still visible to the guest. > > >=20 > > > However it does not clean up the resources until the qemu process is > > > over.=C2=A0 This causes an effective leak if the device is deleted wi= th > > > device_del, as there is no way to close the vdpa device.=C2=A0 This m= akes > > > impossible to re-add that device to this or other QEMU instances unti= l > > > the first instance of QEMU is finished. > > >=20 > > > Move the cleanup from qemu_cleanup to the NIC deletion and to > > > net_cleanup. > > >=20 > > > Fixes: a0d7215e33 ("vhost-vdpa: do not cleanup the vdpa/vhost-net str= uctures if peer nic is present") > > > Reported-by: Lei Yang > > > Signed-off-by: Eugenio P=C3=A9rez > > > Signed-off-by: Jonah Palmer > > > Signed-off-by: Jason Wang > >=20 > > This crashes QEMU when I launch an emulated Xen guest with a Xen PV > > NIC, and quit (using Ctrl-A x on the monitor). >=20 > Eugenio and Jonah, any thoughts on this? It looks like the code > doesn't deal with hub correctly. The interesting part about Xen netback is that it does its own teardown from xen_device_unrealize() because in the case of running under true Xen, it needs to clean up XenStore nodes which are externally visible. It doesn't all just go away when QEMU exits. We fixed a potentially similar issue in commit 84f85eb95f14a ("net: do not delete nics in net_cleanup()")? I should add a test case for this... --=-NXmT5LYMnmniAtV3i3O8 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj jfhCFqxYyRiW8g3cNFAvltDbK5AzcOaR7yVzVGadr4YcCVxjKrEJOgi7WEOH8rUgCNB5cTD8N/Et GfZI+LGqSv0YtNa54T9D1AWJy08ZKkWvfGGIXN9UFAPMJ6OLLH/UUEgFa+7KlrEvMUupDFGnnR06 aDJAwtycb8yXtILj+TvfhLFhafxroXrflspavejQkEiHjNjtHnwbZ+o43g0/yxjwnarGI3kgcak7 nnI9/8Lqpq79tLHYwLajotwLiGTB71AGN5xK+tzB+D4eN9lXayrjcszgbOv2ZCgzExQUAIt98mre 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