Commit ef6dcbdd authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Alex Williamson
Browse files

driver core: Flow the return code from ->probe() through to sysfs bind 



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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/20210617142218.1877096-4-hch@lst.de


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent e1499647

drivers/base/bus.c

+1 −5
Original line number Diff line number Diff line
@@ -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);

drivers/base/dd.c

+20 −9
Original line number Diff line number Diff line
@@ -607,10 +607,10 @@ 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;

	}
@@ -653,7 +653,6 @@ 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;
@@ -746,8 +745,8 @@ 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.
@@ -882,7 +881,14 @@ 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)
@@ -1038,7 +1044,7 @@ 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)

{
@@ -1048,6 +1054,9 @@ 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;

}
@@ -1114,7 +1123,9 @@ 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;

}