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From: Christoph Hellwig <hch@lst.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Kirti Wankhede <kwankhede@nvidia.com>
Cc: David Airlie <airlied@linux.ie>,
	Tony Krowiak <akrowiak@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>, Daniel Vetter <daniel@ffwll.ch>,
	dri-devel@lists.freedesktop.org,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	intel-gfx@lists.freedesktop.org,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Jason Herne <jjherne@linux.ibm.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-s390@vger.kernel.org, Halil Pasic <pasic@linux.ibm.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind
Date: Mon, 14 Jun 2021 17:08:39 +0200	[thread overview]
Message-ID: <20210614150846.4111871-4-hch@lst.de> (raw)
In-Reply-To: <20210614150846.4111871-1-hch@lst.de>

Currently really_probe() returns 1 on success and 0 if the probe() call
fails. This return code arrangement is designed to be useful for
__device_attach_driver() which is walking the device list and trying every
driver. 0 means to keep trying.

However, it is not useful for the other places that call through to
really_probe() that do actually want to see the probe() return code.

For instance bind_store() would be better to return the actual error code
from the driver's probe method, not discarding it and returning -ENODEV.

Reorganize things so that really_probe() returns the error code from
->probe as a (inverted) positive number, and 0 for successful attach.

With this, __device_attach_driver can ignore the (positive) probe errors,
return 1 to exit the loop for a successful binding and pass on the
other negative errors, while device_driver_attach simplify inverts the
positive errors and returns all errors to the sysfs code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/base/bus.c |  6 +-----
 drivers/base/dd.c  | 29 ++++++++++++++++++++---------
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 7de13302e8c8..1f6b4bd61056 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -212,13 +212,9 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
 	dev = bus_find_device_by_name(bus, NULL, buf);
 	if (dev && driver_match_device(drv, dev)) {
 		err = device_driver_attach(drv, dev);
-
-		if (err > 0) {
+		if (!err) {
 			/* success */
 			err = count;
-		} else if (err == 0) {
-			/* driver didn't accept device */
-			err = -ENODEV;
 		}
 	}
 	put_device(dev);
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 999bc737a8f0..4c6af8c062c8 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -605,10 +605,10 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 	probe_ret = call_driver_probe(dev, drv);
 	if (probe_ret) {
 		/*
-		 * Ignore errors returned by ->probe so that the next driver can
-		 * try its luck.
+		 * Return probe errors as positive values so that the callers
+		 * can distinguish them from other errors.
 		   */
-		ret = 0;
+		ret = -probe_ret;
 		goto probe_failed;
 	} 
 
@@ -651,7 +651,6 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 		dev->pm_domain->sync(dev);
 
 	driver_bound(dev);
-	ret = 1;
 	pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 		 drv->bus->name, __func__, dev_name(dev), drv->name);
 	goto done;
@@ -744,8 +743,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe);
  * @dev: device to try to bind to the driver
  *
  * This function returns -ENODEV if the device is not registered, -EBUSY if it
- * already has a driver, and 1 if the device is bound successfully and 0
- * otherwise.
+ * already has a driver, 0 if the device is bound successfully and a positive
+ * (inverted) error code for failures from the ->probe method.
  *
  * This function must be called with @dev lock held.  When called for a
  * USB interface, @dev->parent lock must be held as well.
@@ -880,7 +879,14 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
 	if (data->check_async && async_allowed != data->want_async)
 		return 0;
 
-	return driver_probe_device(drv, dev);
+	/*
+	 * Ignore errors returned by ->probe so that the next driver can try
+	 * its luck.
+	 */
+	ret = driver_probe_device(drv, dev);
+	if (ret < 0)
+		return ret;
+	return ret == 0;
 }
 
 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
@@ -1036,7 +1042,7 @@ 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.
+ * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
  */
 int device_driver_attach(struct device_driver *drv, struct device *dev)
 {
@@ -1046,6 +1052,9 @@ int device_driver_attach(struct device_driver *drv, struct device *dev)
 	ret = driver_probe_device(drv, dev);
 	__device_driver_unlock(dev, dev->parent);
 
+	/* also return probe errors as normal negative errnos */
+	if (ret > 0)
+		ret = -ret;
 	return ret;
 }
 
@@ -1112,7 +1121,9 @@ 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);
+	__device_driver_unlock(dev, dev->parent);
 
 	return 0;
 }
-- 
2.30.2


WARNING: multiple messages have this Message-ID
From: Christoph Hellwig <hch@lst.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Kirti Wankhede <kwankhede@nvidia.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>,
	Jason Herne <jjherne@linux.ibm.com>,
	kvm@vger.kernel.org, Vasily Gorbik <gor@linux.ibm.com>,
	Jonathan Corbet <corbet@lwn.net>, David Airlie <airlied@linux.ie>,
	linux-s390@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	linux-doc@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	intel-gfx@lists.freedesktop.org
Subject: [Intel-gfx] [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind
Date: Mon, 14 Jun 2021 17:08:39 +0200	[thread overview]
Message-ID: <20210614150846.4111871-4-hch@lst.de> (raw)
In-Reply-To: <20210614150846.4111871-1-hch@lst.de>

Currently really_probe() returns 1 on success and 0 if the probe() call
fails. This return code arrangement is designed to be useful for
__device_attach_driver() which is walking the device list and trying every
driver. 0 means to keep trying.

However, it is not useful for the other places that call through to
really_probe() that do actually want to see the probe() return code.

For instance bind_store() would be better to return the actual error code
from the driver's probe method, not discarding it and returning -ENODEV.

Reorganize things so that really_probe() returns the error code from
->probe as a (inverted) positive number, and 0 for successful attach.

With this, __device_attach_driver can ignore the (positive) probe errors,
return 1 to exit the loop for a successful binding and pass on the
other negative errors, while device_driver_attach simplify inverts the
positive errors and returns all errors to the sysfs code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/base/bus.c |  6 +-----
 drivers/base/dd.c  | 29 ++++++++++++++++++++---------
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 7de13302e8c8..1f6b4bd61056 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -212,13 +212,9 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
 	dev = bus_find_device_by_name(bus, NULL, buf);
 	if (dev && driver_match_device(drv, dev)) {
 		err = device_driver_attach(drv, dev);
-
-		if (err > 0) {
+		if (!err) {
 			/* success */
 			err = count;
-		} else if (err == 0) {
-			/* driver didn't accept device */
-			err = -ENODEV;
 		}
 	}
 	put_device(dev);
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 999bc737a8f0..4c6af8c062c8 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -605,10 +605,10 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 	probe_ret = call_driver_probe(dev, drv);
 	if (probe_ret) {
 		/*
-		 * Ignore errors returned by ->probe so that the next driver can
-		 * try its luck.
+		 * Return probe errors as positive values so that the callers
+		 * can distinguish them from other errors.
 		   */
-		ret = 0;
+		ret = -probe_ret;
 		goto probe_failed;
 	} 
 
@@ -651,7 +651,6 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 		dev->pm_domain->sync(dev);
 
 	driver_bound(dev);
-	ret = 1;
 	pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 		 drv->bus->name, __func__, dev_name(dev), drv->name);
 	goto done;
@@ -744,8 +743,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe);
  * @dev: device to try to bind to the driver
  *
  * This function returns -ENODEV if the device is not registered, -EBUSY if it
- * already has a driver, and 1 if the device is bound successfully and 0
- * otherwise.
+ * already has a driver, 0 if the device is bound successfully and a positive
+ * (inverted) error code for failures from the ->probe method.
  *
  * This function must be called with @dev lock held.  When called for a
  * USB interface, @dev->parent lock must be held as well.
@@ -880,7 +879,14 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
 	if (data->check_async && async_allowed != data->want_async)
 		return 0;
 
-	return driver_probe_device(drv, dev);
+	/*
+	 * Ignore errors returned by ->probe so that the next driver can try
+	 * its luck.
+	 */
+	ret = driver_probe_device(drv, dev);
+	if (ret < 0)
+		return ret;
+	return ret == 0;
 }
 
 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
@@ -1036,7 +1042,7 @@ 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.
+ * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
  */
 int device_driver_attach(struct device_driver *drv, struct device *dev)
 {
@@ -1046,6 +1052,9 @@ int device_driver_attach(struct device_driver *drv, struct device *dev)
 	ret = driver_probe_device(drv, dev);
 	__device_driver_unlock(dev, dev->parent);
 
+	/* also return probe errors as normal negative errnos */
+	if (ret > 0)
+		ret = -ret;
 	return ret;
 }
 
@@ -1112,7 +1121,9 @@ 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);
+	__device_driver_unlock(dev, dev->parent);
 
 	return 0;
 }
-- 
2.30.2

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  parent reply	other threads:[~2021-06-14 15:09 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14 15:08 Allow mdev drivers to directly create the vfio_device (v2 / alternative) Christoph Hellwig
2021-06-14 15:08 ` [Intel-gfx] " Christoph Hellwig
2021-06-14 15:08 ` [PATCH 01/10] driver core: Pull required checks into driver_probe_device() Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-15  5:16   ` Greg Kroah-Hartman
2021-06-15  5:16     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15  5:16     ` Greg Kroah-Hartman
2021-06-15 10:27   ` Cornelia Huck
2021-06-15 10:27     ` [Intel-gfx] " Cornelia Huck
2021-06-15 10:27     ` Cornelia Huck
2021-06-14 15:08 ` [PATCH 02/10] driver core: Better distinguish probe errors in really_probe Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-14 18:47   ` Kirti Wankhede
2021-06-14 18:47     ` [Intel-gfx] " Kirti Wankhede
2021-06-14 18:47     ` Kirti Wankhede
2021-06-15  5:17   ` Greg Kroah-Hartman
2021-06-15  5:17     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15  5:17     ` Greg Kroah-Hartman
2021-06-15  5:48     ` Christoph Hellwig
2021-06-15  5:48       ` [Intel-gfx] " Christoph Hellwig
2021-06-14 15:08 ` Christoph Hellwig [this message]
2021-06-14 15:08   ` [Intel-gfx] [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig
2021-06-15  5:18   ` Greg Kroah-Hartman
2021-06-15  5:18     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15  5:18     ` Greg Kroah-Hartman
2021-06-15 10:31   ` Cornelia Huck
2021-06-15 10:31     ` [Intel-gfx] " Cornelia Huck
2021-06-15 10:31     ` Cornelia Huck
2021-06-14 15:08 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during " Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-14 22:43   ` Jason Gunthorpe
2021-06-14 22:43     ` [Intel-gfx] " Jason Gunthorpe
2021-06-14 22:43     ` Jason Gunthorpe
2021-06-14 15:08 ` [PATCH 05/10] driver core: Export device_driver_attach() Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-15  5:20   ` Greg Kroah-Hartman
2021-06-15  5:20     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15  5:20     ` Greg Kroah-Hartman
2021-06-15 10:49   ` Cornelia Huck
2021-06-15 10:49     ` [Intel-gfx] " Cornelia Huck
2021-06-15 10:49     ` Cornelia Huck
2021-06-14 15:08 ` [PATCH 06/10] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 10:50   ` Cornelia Huck
2021-06-15 10:50     ` [Intel-gfx] " Cornelia Huck
2021-06-15 10:50     ` Cornelia Huck
2021-06-14 15:08 ` [PATCH 07/10] vfio/mdev: Allow the mdev_parent_ops to specify the device driver to bind Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 10:54   ` Cornelia Huck
2021-06-15 10:54     ` [Intel-gfx] " Cornelia Huck
2021-06-15 10:54     ` Cornelia Huck
2021-06-14 15:08 ` [PATCH 08/10] vfio/mtty: Convert to use vfio_register_group_dev() Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-14 15:08 ` [PATCH 09/10] vfio/mdpy: " Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-14 15:08 ` [PATCH 10/10] vfio/mbochs: " Christoph Hellwig
2021-06-14 15:08   ` [Intel-gfx] " Christoph Hellwig
2021-06-15  0:20 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/10] driver core: Pull required checks into driver_probe_device() Patchwork
2021-06-15  0:23 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-06-15  0:49 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-06-15  5:21 ` Allow mdev drivers to directly create the vfio_device (v2 / alternative) Greg Kroah-Hartman
2021-06-15  5:21   ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15  5:21   ` Greg Kroah-Hartman
2021-06-15  5:50   ` Christoph Hellwig
2021-06-15  5:50     ` [Intel-gfx] " Christoph Hellwig
2021-06-15 15:27     ` Jason Gunthorpe
2021-06-15 15:27       ` [Intel-gfx] " Jason Gunthorpe
2021-06-15 15:27       ` Jason Gunthorpe
2021-06-15  9:37 ` [Intel-gfx] ✓ Fi.CI.IGT: success for series starting with [01/10] driver core: Pull required checks into driver_probe_device() Patchwork
  -- strict thread matches above, loose matches on Subject: below --
2021-06-17 14:22 Allow mdev drivers to directly create the vfio_device (v4) Christoph Hellwig
2021-06-17 14:22 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig
2021-06-15 13:35 Allow mdev drivers to directly create the vfio_device (v3) Christoph Hellwig
2021-06-15 13:35 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig
2021-06-08  0:55 [PATCH 00/10] Allow mdev drivers to directly create the vfio_device 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

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