drivercore: revert addition of of_match to struct device

Commit b826291c, "drivercore/dt: add a match table pointer to struct
device" added an of_match pointer to struct device to cache the
of_match_table entry discovered at driver match time.  This was unsafe
because matching is not an atomic operation with probing a driver.  If
two or more drivers are attempted to be matched to a driver at the
same time, then the cached matching entry pointer could get
overwritten.

This patch reverts the of_match cache pointer and reworks all users to
call of_match_device() directly instead.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

2 files changed, 6 insertions, 7 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index ab8dfc095709..d08399db6e2c 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -442,7 +442,6 @@ struct device {
         struct dev_archdata     archdata;
 
         struct device_node      *of_node; /* associated device tree node */
-        const struct of_device_id *of_match; /* matching of_device_id from driver */
 
         dev_t                   devt;   /* dev_t, creates the sysfs "dev" */
 
diff --git a/include/linux/of_device.h b/include/linux/of_device.h
index b33d68814a73..ae5638480ef2 100644
--- a/include/linux/of_device.h
+++ b/include/linux/of_device.h
@@ -21,12 +21,7 @@ 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)
 {
-        const struct of_device_id *match;
-
-        match = of_match_device(drv->of_match_table, dev);
-        if (match)
-                dev->of_match = match;
-        return match != NULL;
+        return of_match_device(drv->of_match_table, dev) != NULL;
 }
 
 extern struct platform_device *of_dev_get(struct platform_device *dev);
@@ -62,6 +57,11 @@ static inline int of_device_uevent(struct device *dev,
 
 static inline void of_device_node_put(struct device *dev) { }
 
+static inline const struct of_device_id *of_match_device(
+                const struct of_device_id *matches, const struct device *dev)
+{
+        return NULL;
+}
 #endif /* CONFIG_OF_DEVICE */
 
 #endif /* _LINUX_OF_DEVICE_H */