ChangeSet 1.2339, 2005/04/01 11:48:28-08:00, khali at linux-fr.org
[PATCH] I2C: pcf8574 doesn't need a lock
While investigating the i2c chips drivers that were not properly
locking, we found that the pcf8574 driver does the exact contrary. It
uses a lock where it's not needed.
While we were there, we did some additional cleanups to the driver:
1* Merge pcf8574_update_client() in show_read(), as it was the only user
and the function became trivial once the locking was removed.
2* Add a validity check on values provided by user-space.
Aurelien Jarno tested the modified code for confirmation and it worked
just fine.
Signed-off-by: Jean Delvare <khali at linux-fr.org>
Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>
Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>
drivers/i2c/chips/pcf8574.c | 27 +++++++++------------------
1 files changed, 9 insertions(+), 18 deletions(-)
diff -Nru a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c
--- a/drivers/i2c/chips/pcf8574.c 2005-04-01 11:53:38 -08:00
+++ b/drivers/i2c/chips/pcf8574.c 2005-04-01 11:53:38 -08:00
@@ -56,7 +56,6 @@
/* Each client has this additional data */
struct pcf8574_data {
struct i2c_client client;
- struct semaphore update_lock;
u8 read, write; /* Register values */
};
@@ -65,7 +64,6 @@
static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
static int pcf8574_detach_client(struct i2c_client *client);
static void pcf8574_init_client(struct i2c_client *client);
-static struct pcf8574_data *pcf8574_update_client(struct device *dev);
/* This is the driver that will be inserted */
static struct i2c_driver pcf8574_driver = {
@@ -80,7 +78,9 @@
/* following are the sysfs callback functions */
static ssize_t show_read(struct device *dev, char *buf)
{
- struct pcf8574_data *data = pcf8574_update_client(dev);
+ struct i2c_client *client = to_i2c_client(dev);
+ struct pcf8574_data *data = i2c_get_clientdata(client);
+ data->read = i2c_smbus_read_byte(client);
return sprintf(buf, "%u\n", data->read);
}
@@ -97,7 +97,12 @@
{
struct i2c_client *client = to_i2c_client(dev);
struct pcf8574_data *data = i2c_get_clientdata(client);
- data->write = simple_strtoul(buf, NULL, 10);
+ unsigned long val = simple_strtoul(buf, NULL, 10);
+
+ if (val > 0xff)
+ return -EINVAL;
+
+ data->write = val;
i2c_smbus_write_byte(client, data->write);
return count;
}
@@ -157,7 +162,6 @@
/* Fill in the remaining client fields and put it into the global list */
strlcpy(new_client->name, client_name, I2C_NAME_SIZE);
- init_MUTEX(&data->update_lock);
/* Tell the I2C layer a new client has arrived */
if ((err = i2c_attach_client(new_client)))
@@ -200,19 +204,6 @@
struct pcf8574_data *data = i2c_get_clientdata(client);
data->write = PCF8574_INIT;
i2c_smbus_write_byte(client, data->write);
-}
-
-static struct pcf8574_data *pcf8574_update_client(struct device *dev)
-{
- struct i2c_client *client = to_i2c_client(dev);
- struct pcf8574_data *data = i2c_get_clientdata(client);
-
- down(&data->update_lock);
- dev_dbg(&client->dev, "Starting pcf8574 update\n");
- data->read = i2c_smbus_read_byte(client);
- up(&data->update_lock);
-
- return data;
}
static int __init pcf8574_init(void)
