[PATCH 3/3] driver core: bus: Correct API bus_rescan_devices() behavior

From: Zijun Hu
Date: Wed Sep 04 2024 - 08:59:31 EST


From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>

API bus_rescan_devices() should ideally scan drivers for a bus's devices
as many as possible, but it really stops scanning for remaining devices
even if a device encounters inconsequential errors such as -EPROBE_DEFER
and -ENODEV, fixed by ignoring such inconsequential errors during scanning.

By the way, Neither the API's return value nor device_reprobe()'s existing
logic are changed.

Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
---
drivers/base/bus.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 6b5ea82a44c1..31d9d5d08934 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -58,9 +58,6 @@ static int __must_check bus_rescan_single_device(struct device *dev)
return ret;
}

-static int __must_check bus_rescan_devices_helper(struct device *dev,
- void *data);
-
/**
* bus_to_subsys - Turn a struct bus_type into a struct subsys_private
*
@@ -790,15 +787,18 @@ static int __must_check bus_rescan_devices_helper(struct device *dev,
void *data)
{
int ret = 0;
+ int *first_error = data;

- if (!dev->driver) {
- if (dev->parent && dev->bus->need_parent_lock)
- device_lock(dev->parent);
- ret = device_attach(dev);
- if (dev->parent && dev->bus->need_parent_lock)
- device_unlock(dev->parent);
- }
- return ret < 0 ? ret : 0;
+ ret = bus_rescan_single_device(dev);
+
+ if (ret >= 0)
+ return 0;
+ if (!*first_error)
+ *first_error = ret;
+ /* Ignore these errors to scan drivers for next device */
+ if (ret == -EPROBE_DEFER || ret == -ENODEV)
+ return 0;
+ return ret;
}

/**
@@ -811,7 +811,10 @@ static int __must_check bus_rescan_devices_helper(struct device *dev,
*/
int bus_rescan_devices(const struct bus_type *bus)
{
- return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
+ int err = 0;
+
+ bus_for_each_dev(bus, NULL, &err, bus_rescan_devices_helper);
+ return err;
}
EXPORT_SYMBOL_GPL(bus_rescan_devices);

@@ -826,9 +829,13 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices);
*/
int device_reprobe(struct device *dev)
{
+ int ret;
+
if (dev->driver)
device_driver_detach(dev);
- return bus_rescan_devices_helper(dev, NULL);
+
+ ret = bus_rescan_single_device(dev);
+ return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(device_reprobe);


--
2.34.1