[PATCH 1/2] driver core: platform: removed unneeded variable from __platform_driver_probe()

[PATCH 1/2] driver core: platform: removed unneeded variable from __platform_driver_probe()

[Greg Kroah-Hartman]

In the reworking of the function __platform_driver_probe() over the
years, it turns out that the variable 'code' does not actually do
anything or mean anything anymore and can be removed to simplify the
logic when trying to read and understand what this function is actually
doing.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/base/platform.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 262555b83bed..423874269f9d 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -906,7 +906,7 @@ static int platform_probe_fail(struct platform_device *pdev)
 int __init_or_module __platform_driver_probe(struct platform_driver *drv,
 		int (*probe)(struct platform_device *), struct module *module)
 {
-	int retval, code;
+	int retval;
 
 	if (drv->driver.probe_type == PROBE_PREFER_ASYNCHRONOUS) {
 		pr_err("%s: drivers registered with %s can not be probed asynchronously\n",
@@ -932,7 +932,7 @@ int __init_or_module __platform_driver_probe(struct platform_driver *drv,
 
 	/* temporary section violation during probe() */
 	drv->probe = probe;
-	retval = code = __platform_driver_register(drv, module);
+	retval = __platform_driver_register(drv, module);
 	if (retval)
 		return retval;
 
@@ -944,11 +944,11 @@ int __init_or_module __platform_driver_probe(struct platform_driver *drv,
 	 */
 	spin_lock(&drv->driver.bus->p->klist_drivers.k_lock);
 	drv->probe = platform_probe_fail;
-	if (code == 0 && list_empty(&drv->driver.p->klist_devices.k_list))
+	if (list_empty(&drv->driver.p->klist_devices.k_list))
 		retval = -ENODEV;
 	spin_unlock(&drv->driver.bus->p->klist_drivers.k_lock);
 
-	if (code != retval)
+	if (retval)
 		platform_driver_unregister(drv);
 	return retval;
 }
-- 
2.39.1

[PATCH 2/2] driver core: platform: simplify __platform_driver_probe()

[Greg Kroah-Hartman]

__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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/base/platform.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 423874269f9d..77510e4f47de 100644
--- 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);
-- 
2.39.1