Commit 01294d82 authored May 18, 2011 by Milton Miller Committed by Grant Likely May 18, 2011

of: fix race when matching drivers



If two drivers are probing devices at the same time, both will write
their match table result to the dev->of_match cache at the same time.

Only write the result if the device matches.

In a thread titled "SBus devices sometimes detected, sometimes not",
Meelis reported his SBus hme was not detected about 50% of the time.
From the debug suggested by Grant it was obvious another driver matched
some devices between the call to match the hme and the hme discovery
failling.

Reported-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Milton Miller <miltonm@bga.com>
[grant.likely: modified to only call of_match_device() once]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

parent 2e9521fd

include/linux/of_device.h

+6 −2

Original line number	Diff line number	Diff line
		@@ -21,8 +21,12 @@ extern void of_device_make_bus_id(struct device *dev);
		static inline int of_driver_match_device(struct device *dev,
		const struct device_driver *drv)
		{
		dev->of_match = of_match_device(drv->of_match_table, dev);
		return dev->of_match != NULL;
		const struct of_device_id *match;

		match = of_match_device(drv->of_match_table, dev);
		if (match)
		dev->of_match = match;
		return match != NULL;
		}

		extern struct platform_device of_dev_get(struct platform_device dev);