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Wysocki" Subject: [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind Date: Mon, 7 Jun 2021 21:55:46 -0300 Message-Id: <4-v1-324b2038f212+1041f1-vfio3a_jgg@nvidia.com> In-Reply-To: <0-v1-324b2038f212+1041f1-vfio3a_jgg@nvidia.com> References: Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [47.55.113.94] X-ClientProxiedBy: BL1PR13CA0252.namprd13.prod.outlook.com (2603:10b6:208:2ba::17) To BL0PR12MB5506.namprd12.prod.outlook.com (2603:10b6:208:1cb::22) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mlx.ziepe.ca (47.55.113.94) by BL1PR13CA0252.namprd13.prod.outlook.com (2603:10b6:208:2ba::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4219.12 via Frontend Transport; Tue, 8 Jun 2021 00:55:54 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1lqQ24-003eKW-H5; Mon, 07 Jun 2021 21:55:52 -0300 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 7d3d86a3-815d-4f0e-e3a9-08d92a182b21 X-MS-TrafficTypeDiagnostic: BL0PR12MB5539: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:972; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?p7ybQ9PyDWdaFK525m0ZmP7cJiuFp0q1hY5M4DTY4JxSg8Z86wv1mLMxzK0d?= =?us-ascii?Q?0rftVcFFhsgahedzTGFW/r6gv6tSdzAhEKL1oHHPuFCcOMllqRbc2jYslcD5?= =?us-ascii?Q?t3eK+MiYZEZdlwxzQyEp2kEwbz7JfhifKznpSASEr0nCGCEJTTHiDe2uM6w/?= =?us-ascii?Q?Sdm0YPmT0aHhRXKJ94ImGg9dIFylzcMID0w/zgbAXAFCpoXtM9gKFSvB1bqc?= =?us-ascii?Q?9xY6iJWh7aufLYaIvFSrRgiOp1M+1PJt4V/DCXYiz54ydLkR1clsNrCokpns?= =?us-ascii?Q?UXAk4ra2bXpvbKH8Xh7ZH8eaAdP++WPbtI/PYbJCgZOWC/0XWK68uuW0Gp9I?= =?us-ascii?Q?7jOiD/DKMkeNN3hJ3kaJDvJHIh+7JpIILN9PQ9sj1tgK0sDbPGCfFeCPkvqD?= =?us-ascii?Q?07DtJJGIfDMBTyaUi6jAviQ3pGHrpgSVuCz2qLnj7zOqo77hwj/7hDZ2CNiC?= =?us-ascii?Q?y6BVHZHCpH6BGB4oYVPr/l49B7Eo8bcoI/jKaWeaWOmsnDOcw6TkKYRuMPE9?= =?us-ascii?Q?JkSPmRIZ9/YjjJiyRZ2DdxieqZiZ8PSHMtw+xfwbZGFHzqV3N7t+5n5PtBgW?= =?us-ascii?Q?w+aWhbkjB+yIm37tTk2gQ/VJJ0Yv5zQasorltYGVNtQeBiJPaoyMYjrCnJIl?= =?us-ascii?Q?Bsu3bQmg3YVy6XVwWM8MrMGYHsrSG9u0JAxUMwlPnNBV5W4BxbvwL1wgVzEL?= =?us-ascii?Q?E+wP369897t9U99JVW17Zqkd7ZsasH6y4vupaP7FnT2JaDWyERwjz71fI3ig?= =?us-ascii?Q?+z8sW35huxW+i1LaP/M53r1G2p2iFVzjXu8q1QBIyvrlGdCuIZQIxy5l4Ssg?= =?us-ascii?Q?Gur5xI1UMlTzjHRM/cmgXVWgMKDS4/B6DNpUpuEhGiODNhkY8kIaaM843Hql?= =?us-ascii?Q?V1VeEnqVxCqEtADBd/daNmdcZT/RCTJL3D6Zkfhtwwv+LGAM8ZkQ/dsUwuur?= =?us-ascii?Q?RiNmh16McPEi9XX9VYoUNN36kz1U9vQq7FHjHnoQ3SBdxmqLamq1f0f1yfBg?= =?us-ascii?Q?Bj8atuJjiAVYS+WxdnKicKy/EwdEN+MT2iBZhKcFjc0SvtPv5pspSY/43Zwq?= =?us-ascii?Q?P6d+EkOnLkbR4tmjWlFES4OnOhKhBWaPoBE1j5ta544yhl7mTudnjVR3oMre?= =?us-ascii?Q?6xD7hnDBZ/EqJWmEagf6ivKJ0wZlwhA5g5s/qkg9jd27+yBwaf71ljFh2Iav?= =?us-ascii?Q?3+jUtyV+BJyJVROGflZg9kOIr2MiJi57E0JEVKCaVUDVVbT+E6hI9jcBVTwk?= =?us-ascii?Q?cpje5mkCMFszr/DguAZ8pnENkZiOQlOFy59hWCZfE+xDDWRylvtAPzuz1m+q?= =?us-ascii?Q?2O9N+zsz2LSzPV2kpnlLj0F/?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7d3d86a3-815d-4f0e-e3a9-08d92a182b21 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Jun 2021 00:55:54.3098 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: /By7hb9n+YM7byv1iXwLXmmJYXzFKlIlHzN/U2Yueo1MX9WO1oGSzYtbIHw+CwJ2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB5539 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org EPROBE_DEFER is an internal kernel error code and it should not be leaked to userspace via the bind_store() sysfs. Userspace doesn't have this constant and cannot understand it. Further, it doesn't really make sense to have userspace trigger a deferred probe via bind_store(), which could eventually succeed, while simultaneously returning an error back. Resolve this by preventing EPROBE_DEFER from triggering a deferred probe and simply relay the whole situation back to userspace as a normal -EAGAIN code. Put this in the device_driver_attach() so the EPROBE_DEFER remains contained to dd.c and the probe() implementations. Signed-off-by: Jason Gunthorpe --- drivers/base/dd.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 7fb58e6219b255..edda7aad43a3f7 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -516,12 +516,17 @@ static DEVICE_ATTR_RO(state_synced); enum { /* Set on output if the -ERR has come from a probe() function */ PROBEF_DRV_FAILED = 1 << 0, + /* + * Set on input to call driver_deferred_probe_add() if -EPROBE_DEFER + * is returned + */ + PROBEF_SCHEDULE_DEFER = 1 << 1, }; static int really_probe(struct device *dev, struct device_driver *drv, unsigned int *flags) { - int ret = -EPROBE_DEFER; + int ret; int local_trigger_count = atomic_read(&deferred_trigger_count); bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && !drv->suppress_bind_attrs; @@ -533,15 +538,18 @@ static int really_probe(struct device *dev, struct device_driver *drv, * wait_for_device_probe() right after that to avoid any races. */ dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); - driver_deferred_probe_add(dev); - return ret; + if (*flags & PROBEF_SCHEDULE_DEFER) + driver_deferred_probe_add(dev); + return -EPROBE_DEFER; } ret = device_links_check_suppliers(dev); - if (ret == -EPROBE_DEFER) - driver_deferred_probe_add_trigger(dev, local_trigger_count); - if (ret) + if (ret) { + if (ret == -EPROBE_DEFER && *flags & PROBEF_SCHEDULE_DEFER) + driver_deferred_probe_add_trigger(dev, + local_trigger_count); return ret; + } atomic_inc(&probe_count); pr_debug("bus: '%s': %s: probing driver %s with device %s\n", @@ -664,7 +672,9 @@ static int really_probe(struct device *dev, struct device_driver *drv, case -EPROBE_DEFER: /* Driver requested deferred probing */ dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name); - driver_deferred_probe_add_trigger(dev, local_trigger_count); + if (*flags & PROBEF_SCHEDULE_DEFER) + driver_deferred_probe_add_trigger(dev, + local_trigger_count); break; case -ENODEV: case -ENXIO: @@ -853,7 +863,7 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) struct device_attach_data *data = _data; struct device *dev = data->dev; bool async_allowed; - int flags = 0; + int flags = PROBEF_SCHEDULE_DEFER; int ret; ret = driver_match_device(drv, dev); @@ -1043,7 +1053,9 @@ static void __device_driver_unlock(struct device *dev, struct device *parent) * @dev: Device to attach it to * * Manually attach driver to a device. Will acquire both @dev lock and - * @dev->parent lock if needed. Returns 0 on success, -ERR on failure. + * @dev->parent lock if needed. Returns 0 on success, -ERR on failure. If + * EPROBE_DEFER is returned from probe() then no background probe is scheduled + * and -EAGAIN will be returned. */ int device_driver_attach(struct device_driver *drv, struct device *dev) { @@ -1061,6 +1073,8 @@ int device_driver_attach(struct device_driver *drv, struct device *dev) __device_driver_unlock(dev, dev->parent); + if (ret == -EPROBE_DEFER) + return -EAGAIN; return ret; } @@ -1068,7 +1082,7 @@ static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie) { struct device *dev = _dev; struct device_driver *drv; - unsigned int flags = 0; + unsigned int flags = PROBEF_SCHEDULE_DEFER; int ret; __device_driver_lock(dev, dev->parent); @@ -1083,6 +1097,7 @@ static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie) static int __driver_attach(struct device *dev, void *data) { + unsigned int flags = PROBEF_SCHEDULE_DEFER; struct device_driver *drv = data; int ret; @@ -1128,7 +1143,9 @@ static int __driver_attach(struct device *dev, void *data) return 0; } - device_driver_attach(drv, dev); + __device_driver_lock(dev, dev->parent); + driver_probe_device(drv, dev, &flags); + __device_driver_unlock(dev, dev->parent); return 0; } -- 2.31.1