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/watchdog/mpc8xxx_wdt.c b/drivers/watchdog/mpc8xxx_wdt.c
index 528bceb220fd..eed5436ffb51 100644
--- a/drivers/watchdog/mpc8xxx_wdt.c
+++ b/drivers/watchdog/mpc8xxx_wdt.c
@@ -185,17 +185,20 @@ static struct miscdevice mpc8xxx_wdt_miscdev = {
         .fops   = &mpc8xxx_wdt_fops,
 };
 
+static const struct of_device_id mpc8xxx_wdt_match[];
 static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev)
 {
         int ret;
+        const struct of_device_id *match;
         struct device_node *np = ofdev->dev.of_node;
         struct mpc8xxx_wdt_type *wdt_type;
         u32 freq = fsl_get_sys_freq();
         bool enabled;
 
-        if (!ofdev->dev.of_match)
+        match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
+        if (!match)
                 return -EINVAL;
-        wdt_type = ofdev->dev.of_match->data;
+        wdt_type = match->data;
 
         if (!freq || freq == -1)
                 return -EINVAL;