misc/isl29020: signedness bug in als_sensing_range_store()

"ret_val" is supposed to be signed here or the error handling breaks.
Also we should check the return value from i2c_smbus_read_byte_data().

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/misc/isl29020.c b/drivers/misc/isl29020.c
index 34fe835921c4..ca47e6285075 100644
--- a/drivers/misc/isl29020.c
+++ b/drivers/misc/isl29020.c
@@ -87,7 +87,7 @@ static ssize_t als_sensing_range_store(struct device *dev,
                 struct device_attribute *attr, const  char *buf, size_t count)
 {
         struct i2c_client *client = to_i2c_client(dev);
-        unsigned int ret_val;
+        int ret_val;
         unsigned long val;
 
         if (strict_strtoul(buf, 10, &val))
@@ -106,6 +106,8 @@ static ssize_t als_sensing_range_store(struct device *dev,
                 val = 4;
 
         ret_val = i2c_smbus_read_byte_data(client, 0x00);
+        if (ret_val < 0)
+                return ret_val;
 
         ret_val &= 0xFC; /*reset the bit before setting them */
         ret_val |= val - 1;