From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262862AbVDAUGE (ORCPT ); Fri, 1 Apr 2005 15:06:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262869AbVDAUGE (ORCPT ); Fri, 1 Apr 2005 15:06:04 -0500 Received: from mail.kroah.org ([69.55.234.183]:32968 "EHLO perch.kroah.org") by vger.kernel.org with ESMTP id S262862AbVDAUEZ convert rfc822-to-8bit (ORCPT ); Fri, 1 Apr 2005 15:04:25 -0500 Cc: khali@linux-fr.org Subject: [PATCH] I2C: pcf8574 doesn't need a lock In-Reply-To: <20050401200324.GA12854@kroah.com> X-Mailer: gregkh_patchbomb Date: Fri, 1 Apr 2005 12:04:14 -0800 Message-Id: <11123858541382@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Reply-To: Greg K-H To: linux-kernel@vger.kernel.org, sensors@Stimpy.netroedge.com Content-Transfer-Encoding: 7BIT From: Greg KH Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ChangeSet 1.2339, 2005/04/01 11:48:28-08:00, khali@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 Signed-off-by: Aurelien Jarno Signed-off-by: Greg Kroah-Hartman 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)