diff mbox series

[03/10] driver core: Flow the return code from ->probe() through to sysfs bind

Message ID 20210614150846.4111871-4-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [01/10] driver core: Pull required checks into driver_probe_device() | expand

Commit Message

Christoph Hellwig June 14, 2021, 3:08 p.m. UTC
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(-)

Comments

Greg Kroah-Hartman June 15, 2021, 5:18 a.m. UTC | #1
On Mon, Jun 14, 2021 at 05:08:39PM +0200, Christoph Hellwig wrote:
> 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(-)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cornelia Huck June 15, 2021, 10:31 a.m. UTC | #2
On Mon, Jun 14 2021, Christoph Hellwig <hch@lst.de> wrote:

> 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(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>
diff mbox series

Patch

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;
 }