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Miller" , "netdev@vger.kernel.org" , Andrew Lunn , Florian Fainelli , Paul Gortmaker , Pablo Neira Ayuso , Jiri Benc , Cong Wang , Jamal Hadi Salim , Stephen Hemminger , Eric Dumazet , George McCollister , Oleksij Rempel , Jay Vosburgh , Veaceslav Falico , Andy Gospodarek Subject: Re: [RFC PATCH net-next 05/13] net: bonding: hold the netdev lists lock when retrieving device statistics Thread-Topic: [RFC PATCH net-next 05/13] net: bonding: hold the netdev lists lock when retrieving device statistics Thread-Index: AQHWzCvp+5zpZdZumUWV00Rtz8jGw6nq0GsAgAMTFACAAAG6gA== Date: Wed, 9 Dec 2020 00:03:56 +0000 Message-ID: <20201209000355.vv4gaj7sgi6kph27@skbuf> References: <20201206235919.393158-1-vladimir.oltean@nxp.com> <20201206235919.393158-6-vladimir.oltean@nxp.com> <20201207010040.eriknpcidft3qul6@skbuf> <20201208155744.320d694b@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> In-Reply-To: <20201208155744.320d694b@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: kernel.org; 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x-ms-exchange-antispam-messagedata: =?us-ascii?Q?gOF4GHaqxTcCmNtyQWHw1RldVay81rJUQhOy4RVqwIySA1LX4HZixbo6mS4Z?= =?us-ascii?Q?feQ5kiEd9P2AwwUYGhFFnnWXmJ+S3dUpoxiEJCgqTfPsgqBXUi+c0rbSCSUw?= =?us-ascii?Q?Lf/+GUxjRYMiDDqMeYNUNHzdMnawUTh6SC109eEJtTPTjdVMa/T5xPSAdlpp?= =?us-ascii?Q?7RkQPa2RR1izE0R36t3Bn4LMAxFb/84EUp3LAE8hjazTNUeL3SaQ6PdDlB5x?= =?us-ascii?Q?8yo8bEyABsIDODCAnAy4LKe/xhu59DBz9tVk9/SQUe1sDeM+eJCLPVAnGOL+?= =?us-ascii?Q?3CouZ9yFr1MkWNCjvR1zf/g5TC963mFCFN2gjtP14/ajgZK/2M+e1mE4JPFW?= =?us-ascii?Q?kOn58k0mOGSfayt6DFfZ0fl29sEYJEl289/vQqZMhfqbRI36kV95uwuA8rxO?= =?us-ascii?Q?R77dK2emlXdd1exYh0EJIvnARvvEgH3xueMnrioguvJK9SijM9ZUfRY8eqx5?= =?us-ascii?Q?rRj/C4bMXCQY6PSIaQ67+Dy5PgmptWc+VfH8SsWrj6iH7NzVzb8IWiZdlMMx?= =?us-ascii?Q?VPKhpTtQ2rjeZ3s9FvPe+BP0kyNaEQqbY9HW0nvSu0L0tVHsVXik8R+hAo95?= =?us-ascii?Q?x9oNwpqMwKl5h8bd6dHgx+GAnfdwradSs4bbiE2O5Mw1Vngb1UNHq6tUbziw?= =?us-ascii?Q?DhZ5ZBqf+UySlzKhZj/9rCMEy1apHxMDcj8haSA/vCZgJgKBUGrA34NkajFX?= =?us-ascii?Q?atfVsh26ls0rR4yG7Do8d/vE3uZKGx6N+zvuEdJbDDYOEkyaH4Xg9yky/GoA?= =?us-ascii?Q?dq2bjUK9yLjRyhs0QoIdIq3xowr+vMrriyHpap1CclT+THCZ91mNBsM5lxHd?= =?us-ascii?Q?yQ0PhfBhgoxKf7s2ZGBQRKSu6sQjvTSaOASJfRaqb+a0rcBfBrzZQg7OI4tw?= =?us-ascii?Q?G4GrZDchD5GSjwGWarEjp9gs9uhWqRORAa/ZR/tAn9H4EkZJ0w0TA8yFEdmd?= =?us-ascii?Q?JN8p5/ZZfdZxG9W1ccROuVfvptfnwmDZhKQooQMwGLwP45NjZHcI2DGUGatf?= =?us-ascii?Q?dwtt?= x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: VI1PR04MB5696.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 97ef0d07-ac96-4fe3-ff53-08d89bd5ec6f X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Dec 2020 00:03:56.8997 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: SM26J7znaIf2IjircQilTKUrEvsl4fiBdmlz5FT6aWwSE1ow2HryU6GxQy/h1QQiiPGx0sK/MFDLBuP7Q8F+TA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR04MB4815 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Dec 08, 2020 at 03:57:44PM -0800, Jakub Kicinski wrote: > On Mon, 7 Dec 2020 01:00:40 +0000 Vladimir Oltean wrote: > > - ensuring through convention that user space always takes > > net->netdev_lists_lock when calling dev_get_stats, and documenting > > that, and therefore making it unnecessary to lock in bonding. > > This seems like the better option to me. Makes the locking rules pretty > clear. It is non-obvious to me that top-level callers of dev_get_stats should hold a lock as specific as the one protecting the lists of network interfaces. In the vast majority of implementations of dev_get_stats, that lock would not actually protect anything, which would lead into just one more lock that is used for more than it should be. In my tree I had actually already switched over to mutex_lock_nested. Nonetheless, I am still open if you want to make the case that simplicity should prevail over specificity. But in that case, maybe we should just keep on using the RTNL mutex.=