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From: Jason Gunthorpe <jgg@nvidia.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kvm@vger.kernel.org, "Rafael J. Wysocki" <rafael@kernel.org>
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	[thread overview]
Message-ID: <4-v1-324b2038f212+1041f1-vfio3a_jgg@nvidia.com> (raw)
In-Reply-To: <0-v1-324b2038f212+1041f1-vfio3a_jgg@nvidia.com>

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 <jgg@nvidia.com>
---
 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


  parent reply	other threads:[~2021-06-08  0:56 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08  0:55 [PATCH 00/10] Allow mdev drivers to directly create the vfio_device Jason Gunthorpe
2021-06-08  0:55 ` [Intel-gfx] " Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 01/10] driver core: Do not continue searching for drivers if deferred probe is used Jason Gunthorpe
2021-06-08  5:51   ` Christoph Hellwig
2021-06-08  6:44   ` Greg Kroah-Hartman
2021-06-08 12:16     ` Jason Gunthorpe
2021-06-08 13:13       ` Greg Kroah-Hartman
2021-06-08 13:53         ` Jason Gunthorpe
2021-06-08  7:35   ` Greg Kroah-Hartman
2021-06-08 12:17     ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 02/10] driver core: Pull required checks into driver_probe_device() Jason Gunthorpe
2021-06-08  5:59   ` Christoph Hellwig
2021-06-08 12:21     ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Jason Gunthorpe
2021-06-08  6:07   ` Christoph Hellwig
2021-06-08 23:53     ` Jason Gunthorpe
2021-06-08  6:47   ` Greg Kroah-Hartman
2021-06-08 12:30     ` Jason Gunthorpe
2021-06-08 13:16       ` Greg Kroah-Hartman
2021-06-08 14:03         ` Jason Gunthorpe
2021-06-08  0:55 ` Jason Gunthorpe [this message]
2021-06-08  6:14   ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during " Christoph Hellwig
2021-06-08  7:37   ` Greg Kroah-Hartman
2021-06-08  0:55 ` [PATCH 05/10] driver core: Export device_driver_attach() Jason Gunthorpe
2021-06-08  6:19   ` Christoph Hellwig
2021-06-08 12:33     ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 06/10] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE Jason Gunthorpe
2021-06-08  0:55   ` [Intel-gfx] " Jason Gunthorpe
2021-06-08  6:20   ` Christoph Hellwig
2021-06-08  6:20     ` [Intel-gfx] " Christoph Hellwig
2021-06-11 12:40   ` Cornelia Huck
2021-06-11 12:40     ` [Intel-gfx] " Cornelia Huck
2021-06-14 12:35     ` Jason Gunthorpe
2021-06-14 12:35       ` [Intel-gfx] " Jason Gunthorpe
2021-06-14 12:35       ` Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 07/10] vfio/mdev: Allow the mdev_parent_ops to specify the device driver to bind Jason Gunthorpe
2021-06-08  6:21   ` Christoph Hellwig
2021-06-08  0:55 ` [PATCH 08/10] vfio/mtty: Convert to use vfio_register_group_dev() Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 09/10] vfio/mdpy: " Jason Gunthorpe
2021-06-08  0:55 ` [PATCH 10/10] vfio/mbochs: " Jason Gunthorpe
2021-06-08  6:22 ` [PATCH 00/10] Allow mdev drivers to directly create the vfio_device Christoph Hellwig
2021-06-08  6:22   ` [Intel-gfx] " Christoph Hellwig
2021-06-14 14:34 ` Kirti Wankhede
2021-06-14 14:34   ` [Intel-gfx] " Kirti Wankhede
2021-06-14 14:34   ` Kirti Wankhede
2021-06-14 14:36   ` Jason Gunthorpe
2021-06-14 14:36     ` [Intel-gfx] " Jason Gunthorpe
2021-06-14 14:36     ` Jason Gunthorpe
2021-06-14 15:08 Allow mdev drivers to directly create the vfio_device (v2 / alternative) Christoph Hellwig
2021-06-14 15:08 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind Christoph Hellwig
2021-06-14 22:43   ` Jason Gunthorpe
2021-06-14 22:43     ` Jason Gunthorpe
2021-06-15 13:35 Allow mdev drivers to directly create the vfio_device (v3) Christoph Hellwig
2021-06-15 13:35 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind Christoph Hellwig
2021-06-15 14:03   ` Cornelia Huck
2021-06-15 14:03     ` Cornelia Huck
2021-06-15 19:36   ` Alex Williamson
2021-06-15 19:36     ` Alex Williamson
2021-06-17 14:22 Allow mdev drivers to directly create the vfio_device (v4) Christoph Hellwig
2021-06-17 14:22 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind Christoph Hellwig

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