[PATCH 1/3] i3c: master: Update dev_nack_retry_count under maintenance lock

[Adrian Hunter]

Protect master->dev_nack_retry_count against concurrent sysfs updates
by updating it while holding the bus maintenance lock.

Consequently, combine adjacent return statements into one.

For consistency, read dev_nack_retry_count while holding the bus normaluse
lock.

Fixes: b58f47eb39268 ("i3c: add sysfs entry and attribute for Device NACK Retry count")
Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
---
 drivers/i3c/master.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 367e0d6d4a64..66cf5d3bd987 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -744,7 +744,14 @@ static DEVICE_ATTR_RW(hotjoin);
 static ssize_t dev_nack_retry_count_show(struct device *dev,
 					 struct device_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "%u\n", dev_to_i3cmaster(dev)->dev_nack_retry_count);
+	struct i3c_bus *i3cbus = dev_to_i3cbus(dev);
+	ssize_t ret;
+
+	i3c_bus_normaluse_lock(i3cbus);
+	ret = sysfs_emit(buf, "%u\n", dev_to_i3cmaster(dev)->dev_nack_retry_count);
+	i3c_bus_normaluse_unlock(i3cbus);
+
+	return ret;
 }
 
 static ssize_t dev_nack_retry_count_store(struct device *dev,
@@ -762,14 +769,11 @@ static ssize_t dev_nack_retry_count_store(struct device *dev,
 
 	i3c_bus_maintenance_lock(i3cbus);
 	ret = master->ops->set_dev_nack_retry(master, val);
+	if (!ret)
+		master->dev_nack_retry_count = val;
 	i3c_bus_maintenance_unlock(i3cbus);
 
-	if (ret)
-		return ret;
-
-	master->dev_nack_retry_count = val;
-
-	return count;
+	return ret ?: count;
 }
 
 static DEVICE_ATTR_RW(dev_nack_retry_count);
-- 
2.51.0