Commit 84e7c678 authored Mar 16, 2022 by Mark-PK Tsai Committed by Greg Kroah-Hartman Apr 27, 2022

driver core: Prevent overriding async driver of a device before it probe



When there are 2 matched drivers for a device using
async probe mechanism, the dev->p->async_driver might
be overridden by the last attached driver.
So just skip the later one if the previous matched driver
was not handled by async thread yet.

Below is my use case which having this problem.

Make both driver mmcblk and mmc_test allow async probe,
the dev->p->async_driver will be overridden by the later driver
mmc_test and bind to the device then claim it for testing.
When it happen, mmcblk will never do probe again.

Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Link: https://lore.kernel.org/r/20220316074328.1801-1-mark-pk.tsai@mediatek.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 4c32174a

drivers/base/dd.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1081,6 +1081,7 @@ static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)

		__device_driver_lock(dev, dev->parent);
		drv = dev->p->async_driver;
		dev->p->async_driver = NULL;
		ret = driver_probe_device(drv, dev);
		__device_driver_unlock(dev, dev->parent);

		@@ -1127,7 +1128,7 @@ static int __driver_attach(struct device dev, void data)
		*/
		dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
		device_lock(dev);
		if (!dev->driver) {
		if (!dev->driver && !dev->p->async_driver) {
		get_device(dev);
		dev->p->async_driver = drv;
		async_schedule_dev(__driver_attach_async_helper, dev);