Commit 204db60c authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Alex Williamson
Browse files

driver core: Pull required checks into driver_probe_device() 



Checking if the dev is dead or if the dev is already bound is a required
precondition to invoking driver_probe_device(). All the call chains
leading here duplicate these checks.

Add it directly to driver_probe_device() so the precondition is clear and
remove the checks from device_driver_attach() and
__driver_attach_async_helper().

The other call chain going through __device_attach_driver() does have
these same checks but they are inlined into logic higher up the call stack
and can't be removed.

The sysfs uAPI call chain starting at bind_store() is a bit confused
because it reads dev->driver unlocked and returns -ENODEV if it is !NULL,
otherwise it reads it again under lock and returns 0 if it is !NULL. Fix
this to always return -EBUSY and always read dev->driver under its lock.

Done in preparation for the next patches which will add additional
callers to driver_probe_device() and will need these checks as well.

Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
[hch: drop the extra checks in device_driver_attach and bind_store]
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/20210617142218.1877096-2-hch@lst.de


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 009c9aa5

drivers/base/bus.c

+1 −1
Original line number Diff line number Diff line
@@ -210,7 +210,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, 
	int err = -ENODEV;



	dev = bus_find_device_by_name(bus, NULL, buf);

	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {

	if (dev && driver_match_device(drv, dev)) {

		err = device_driver_attach(drv, dev);



		if (err > 0) {

drivers/base/dd.c

+10 −22
Original line number Diff line number Diff line
@@ -733,8 +733,9 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe); 
 * @drv: driver to bind a device to

 * @dev: device to try to bind to the driver

 *

 * This function returns -ENODEV if the device is not registered,

 * 1 if the device is bound successfully and 0 otherwise.

 * 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.

 *

 * This function must be called with @dev lock held.  When called for a

 * USB interface, @dev->parent lock must be held as well.
@@ -745,8 +746,10 @@ static int driver_probe_device(struct device_driver *drv, struct device *dev) 
{

	int ret = 0;



	if (!device_is_registered(dev))

	if (dev->p->dead || !device_is_registered(dev))

		return -ENODEV;

	if (dev->driver)

		return -EBUSY;



	dev->can_match = true;

	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
@@ -1027,17 +1030,10 @@ static void __device_driver_unlock(struct device *dev, struct device *parent) 
 */

int device_driver_attach(struct device_driver *drv, struct device *dev)

{

	int ret = 0;

	int ret;



	__device_driver_lock(dev, dev->parent);



	/*

	 * If device has been removed or someone has already successfully

	 * bound a driver before us just skip the driver probe call.

	 */

	if (!dev->p->dead && !dev->driver)

	ret = driver_probe_device(drv, dev);



	__device_driver_unlock(dev, dev->parent);



	return ret;
@@ -1047,19 +1043,11 @@ static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie) 
{

	struct device *dev = _dev;

	struct device_driver *drv;

	int ret = 0;

	int ret;



	__device_driver_lock(dev, dev->parent);



	drv = dev->p->async_driver;



	/*

	 * If device has been removed or someone has already successfully

	 * bound a driver before us just skip the driver probe call.

	 */

	if (!dev->p->dead && !dev->driver)

	ret = driver_probe_device(drv, dev);



	__device_driver_unlock(dev, dev->parent);



	dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);