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>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/char/hw_random/n2-drv.c b/drivers/char/hw_random/n2-drv.c
index 43ac61978d8..ac6739e085e 100644
--- a/drivers/char/hw_random/n2-drv.c
+++ b/drivers/char/hw_random/n2-drv.c
@@ -619,15 +619,18 @@ static void __devinit n2rng_driver_version(void)
                 pr_info("%s", version);
 }
 
+static const struct of_device_id n2rng_match[];
 static int __devinit n2rng_probe(struct platform_device *op)
 {
+        const struct of_device_id *match;
         int victoria_falls;
         int err = -ENOMEM;
         struct n2rng *np;
 
-        if (!op->dev.of_match)
+        match = of_match_device(n2rng_match, &op->dev);
+        if (!match)
                 return -EINVAL;
-        victoria_falls = (op->dev.of_match->data != NULL);
+        victoria_falls = (match->data != NULL);
 
         n2rng_driver_version();
         np = kzalloc(sizeof(*np), GFP_KERNEL);