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Miller" , Sasha Levin Subject: [PATCH AUTOSEL for 4.15 084/102] net: sched: drop qdisc_reset from dev_graft_qdisc Thread-Topic: [PATCH AUTOSEL for 4.15 084/102] net: sched: drop qdisc_reset from dev_graft_qdisc Thread-Index: AQHTsz52uzct8OMpGkKexZ3wqPdqrg== Date: Sat, 3 Mar 2018 22:24:58 +0000 Message-ID: <20180303222318.26006-84-alexander.levin@microsoft.com> References: <20180303222318.26006-1-alexander.levin@microsoft.com> In-Reply-To: <20180303222318.26006-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;MW2PR2101MB0970;6:FDaIzqvc1Cbgs5c/MUJ3zi6CODpcKKGPuj6sRh+oCGmUnEL6e2W8cmoHeyWUdedflZFCzUxXZ8PUmsKtgHJlXUdwBmddHYdF4IRg7vqWeL5cQEWEIT2vxFgWqBNRI5P4tz/iyD48w86ldst99a+AtYmv7ynpjxygPOkOs4p+7uZJIYfyqbU360d6+aekCIJ/5jSHskyxmNBoEfM/SN7+4K/+stOay6eojxjdMIYngK2hXtn5E9X335G6gTNzSbb1p91ccj8gOFV7uTWox8q6lS4/RjhofodzLyjBhjsE1rLGUSgEMnDLWSRUYnRq5ywTMiiODfub9xhgtNKRmZpb/mCbXPK7uSXhN9LDckCsYpmGmCEUtLTWbLcVTiN6UDo1;5:rgfNLjdZbghR3bQo+F4y+ZvhoB2fph+HSVYQOdNv4F4B9KziNXlA2OHGC6yNrlR/ZGbXN6zGsPO9ouAolttzaCAx0jqh/Q+abqx5lMMFtHD6rYnaB63f5oEE5dG4fM65JPIaZjucATMf1CScEMkbNEphceHI0cHFto48Fsj94Ao=;24:WLTZuEqyy3OpDZYyh3uOFsFQZUH3b6lJ1UZDyGLk4tzH40kXj888SJCKe4Bq40UuKtEjKBH2S8RQnZ/QDreiFjSy5XEBWwbimbUnl0+6g14=;7:ntg2PZOYbT7Fp9y4rued55PxioqKm4GapIUnwmK6Xr90ZZ3tvTV0inJ8d85mCaGwPyW3vn9cfpyvdRrVK7G9R97MW6Fr5wLDgsXphWUgSlEfMAYGycFOvnV43fMKHK5SvBD3Fb1YUtRz6Qg6CIJqJluCzIyW5N4Kvyt85oFdZR5x3lHlyQdwX56WPIdH1abaNmCjOJAaiMWrAAG0MFDei3/S5KRXkoKgQjtV7MIaJg2swaJ5gouCqdbNj+IakXij x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 46f09b9c-d913-4fb9-4414-08d58155e965 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(4627221)(201703031133081)(201702281549075)(48565401081)(5600026)(4604075)(3008032)(2017052603307)(7193020);SRVR:MW2PR2101MB0970; x-ms-traffictypediagnostic: MW2PR2101MB0970: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(89211679590171)(85827821059158); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(61425038)(6040501)(2401047)(5005006)(8121501046)(93006095)(93001095)(10201501046)(3002001)(3231220)(944501244)(52105095)(6055026)(61426038)(61427038)(6041288)(20161123562045)(20161123558120)(20161123560045)(20161123564045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(6072148)(201708071742011);SRVR:MW2PR2101MB0970;BCL:0;PCL:0;RULEID:;SRVR:MW2PR2101MB0970; x-forefront-prvs: 0600F93FE1 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(376002)(39380400002)(366004)(396003)(39860400002)(346002)(199004)(189003)(86362001)(39060400002)(110136005)(4326008)(6506007)(14454004)(99286004)(8936002)(1076002)(36756003)(2906002)(102836004)(76176011)(25786009)(6486002)(316002)(478600001)(3280700002)(107886003)(186003)(54906003)(26005)(81166006)(7736002)(8676002)(6512007)(81156014)(305945005)(72206003)(59450400001)(6436002)(53936002)(6116002)(6666003)(86612001)(68736007)(3846002)(2950100002)(3660700001)(10290500003)(22452003)(10090500001)(2900100001)(106356001)(2501003)(66066001)(97736004)(5660300001)(5250100002)(5890100001)(105586002)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:MW2PR2101MB0970;H:MW2PR2101MB1034.namprd21.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; x-microsoft-antispam-message-info: oytBnsRRzo1LfXVBYoonjMlvmvyPhxa9GX/zBuKMuYKQjpiY6+9vMKp9K29Wz+KVnDpeedOL/D6sYVxPQ4QT+KdLTKKU4y16wPFKotd8XEx/sVRkyRdo8NT5l6cv4ksJI/sG/fhb5e+cll1VQSn7uv9dA1ZVUTf/CgtE335bvqI= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 46f09b9c-d913-4fb9-4414-08d58155e965 X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Mar 2018 22:24:58.5566 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW2PR2101MB0970 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: John Fastabend [ Upstream commit 7bbde83b1860c28a1cc35516352c4e7e5172c29a ] In qdisc_graft_qdisc a "new" qdisc is attached and the 'qdisc_destroy' operation is called on the old qdisc. The destroy operation will wait a rcu grace period and call qdisc_rcu_free(). At which point gso_cpu_skb is free'd along with all stats so no need to zero stats and gso_cpu_skb from the graft operation itself. Further after dropping the qdisc locks we can not continue to call qdisc_reset before waiting an rcu grace period so that the qdisc is detached from all cpus. By removing the qdisc_reset() here we get the correct property of waiting an rcu grace period and letting the qdisc_destroy operation clean up the qdisc correctly. Note, a refcnt greater than 1 would cause the destroy operation to be aborted however if this ever happened the reference to the qdisc would be lost and we would have a memory leak. Signed-off-by: John Fastabend Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sched/sch_generic.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index cac003fddf3e..b8db13708370 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -762,10 +762,6 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev= _queue, root_lock =3D qdisc_lock(oqdisc); spin_lock_bh(root_lock); =20 - /* Prune old scheduler */ - if (oqdisc && refcount_read(&oqdisc->refcnt) <=3D 1) - qdisc_reset(oqdisc); - /* ... and graft new one */ if (qdisc =3D=3D NULL) qdisc =3D &noop_qdisc; @@ -916,6 +912,16 @@ static bool some_qdisc_is_busy(struct net_device *dev) return false; } =20 +static void dev_qdisc_reset(struct net_device *dev, + struct netdev_queue *dev_queue, + void *none) +{ + struct Qdisc *qdisc =3D dev_queue->qdisc_sleeping; + + if (qdisc) + qdisc_reset(qdisc); +} + /** * dev_deactivate_many - deactivate transmissions on several devices * @head: list of devices to deactivate @@ -926,7 +932,6 @@ static bool some_qdisc_is_busy(struct net_device *dev) void dev_deactivate_many(struct list_head *head) { struct net_device *dev; - bool sync_needed =3D false; =20 list_for_each_entry(dev, head, close_list) { netdev_for_each_tx_queue(dev, dev_deactivate_queue, @@ -936,20 +941,25 @@ void dev_deactivate_many(struct list_head *head) &noop_qdisc); =20 dev_watchdog_down(dev); - sync_needed |=3D !dev->dismantle; } =20 /* Wait for outstanding qdisc-less dev_queue_xmit calls. * This is avoided if all devices are in dismantle phase : * Caller will call synchronize_net() for us */ - if (sync_needed) - synchronize_net(); + synchronize_net(); =20 /* Wait for outstanding qdisc_run calls. */ - list_for_each_entry(dev, head, close_list) + list_for_each_entry(dev, head, close_list) { while (some_qdisc_is_busy(dev)) yield(); + /* The new qdisc is assigned at this point so we can safely + * unwind stale skb lists and qdisc statistics + */ + netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL); + if (dev_ingress_queue(dev)) + dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL); + } } =20 void dev_deactivate(struct net_device *dev) --=20 2.14.1