driver core: platform: simplify __platform_driver_probe()

__platform_driver_probe() pokes around in some bus and driver private
lists and locks in a way that is not needed at all.  The code only wants
to know if a device was bound to the driver that was registered, so walk
all devices on the bus to see if there was a match.  If there is not a
match, return an error.  This is the same logic as was originally
present, but just done in a simpler and more obvious way that is not a
layering violation.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230131082459.301603-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 4238742..77510e4 100644 (file)
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -883,6 +883,13 @@ static int platform_probe_fail(struct platform_device *pdev)
        return -ENXIO;
 }
 
+static int is_bound_to_driver(struct device *dev, void *driver)
+{
+       if (dev->driver == driver)
+               return 1;
+       return 0;
+}
+
 /**
  * __platform_driver_probe - register driver for non-hotpluggable device
  * @drv: platform driver structure
@@ -936,20 +943,17 @@ int __init_or_module __platform_driver_probe(struct platform_driver *drv,
        if (retval)
                return retval;
 
-       /*
-        * Fixup that section violation, being paranoid about code scanning
-        * the list of drivers in order to probe new devices.  Check to see
-        * if the probe was successful, and make sure any forced probes of
-        * new devices fail.
-        */
-       spin_lock(&drv->driver.bus->p->klist_drivers.k_lock);
+       /* Force all new probes of this driver to fail */
        drv->probe = platform_probe_fail;
-       if (list_empty(&drv->driver.p->klist_devices.k_list))
-               retval = -ENODEV;
-       spin_unlock(&drv->driver.bus->p->klist_drivers.k_lock);
 
-       if (retval)
+       /* Walk all platform devices and see if any actually bound to this driver.
+        * If not, return an error as the device should have done so by now.
+        */
+       if (!bus_for_each_dev(&platform_bus_type, NULL, &drv->driver, is_bound_to_driver)) {
+               retval = -ENODEV;
                platform_driver_unregister(drv);
+       }
+
        return retval;
 }
 EXPORT_SYMBOL_GPL(__platform_driver_probe);