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, 6 insertions, 3 deletions

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 75b984c519a..107397a606b 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -560,15 +560,18 @@ static struct i2c_adapter mpc_ops = {
         .timeout = HZ,
 };
 
+static const struct of_device_id mpc_i2c_of_match[];
 static int __devinit fsl_i2c_probe(struct platform_device *op)
 {
+        const struct of_device_id *match;
         struct mpc_i2c *i2c;
         const u32 *prop;
         u32 clock = MPC_I2C_CLOCK_LEGACY;
         int result = 0;
         int plen;
 
-        if (!op->dev.of_match)
+        match = of_match_device(mpc_i2c_of_match, &op->dev);
+        if (!match)
                 return -EINVAL;
 
         i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
@@ -605,8 +608,8 @@ static int __devinit fsl_i2c_probe(struct platform_device *op)
                         clock = *prop;
         }
 
-        if (op->dev.of_match->data) {
-                struct mpc_i2c_data *data = op->dev.of_match->data;
+        if (match->data) {
+                struct mpc_i2c_data *data = match->data;
                 data->setup(op->dev.of_node, i2c, clock, data->prescaler);
         } else {
                 /* Backwards compatibility */