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driver core: Pull required checks into driver_probe_device()

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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: Jason Gunthorpe <jgg@nvidia.com>
[hch: drop the extra checks in device_driver_attach and bind_store]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/20210617142218.1877096-2-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Jason Gunthorpe 2021-06-17 16:22:09 +02:00 committed by Alex Williamson
parent 009c9aa5be
commit 204db60c83
2 changed files with 11 additions and 23 deletions
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2
drivers/base/bus.c
View File

@ -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) {

32
drivers/base/dd.c
View File

@ -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);
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);
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);