iio: st_sensors: simplify buffer address handling

BugLink: https://bugs.launchpad.net/bugs/1676356
The driver goes to some length to dynamically allocate an array
to hold the channel addresses. However no ST sensor has more than
three channels (x, y, z at most). Instead of kmalloc():ing and
kfree():in the address array, just use a fixed array of three
elements.

Cc: Giuseppe Barba <giuseppe.barba@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
(cherry picked from commit e6e45420f41fc613569e8bb6d15e0472dc0ea1ab)
Signed-off-by: Shrirang Bagul <shrirang.bagul@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/drivers/iio/common/st_sensors/st_sensors_buffer.c b/drivers/iio/common/st_sensors/st_sensors_buffer.c
index 249743de67b80bcb63e2b14da1041a91636ffd78..106d67db4204fd1304a11ae5f4fc2089343a8c90 100644 (file)
--- a/drivers/iio/common/st_sensors/st_sensors_buffer.c
+++ b/drivers/iio/common/st_sensors/st_sensors_buffer.c
@@ -24,7 +24,7 @@
 
 int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
 {
-       u8 *addr;
+       u8 addr[3]; /* no ST sensor has more than 3 channels */
        int i, n = 0, len;
        struct st_sensor_data *sdata = iio_priv(indio_dev);
        unsigned int num_data_channels = sdata->num_data_channels;
@@ -32,12 +32,6 @@ int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
                DIV_ROUND_UP(indio_dev->channels[0].scan_type.realbits +
                                indio_dev->channels[0].scan_type.shift, 8);
 
-       addr = kmalloc(num_data_channels, GFP_KERNEL);
-       if (!addr) {
-               len = -ENOMEM;
-               goto st_sensors_get_buffer_element_error;
-       }
-
        for (i = 0; i < num_data_channels; i++) {
                if (test_bit(i, indio_dev->active_scan_mask)) {
                        addr[n] = indio_dev->channels[i].address;
@@ -58,10 +52,8 @@ int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
                        u8 *rx_array;
                        rx_array = kmalloc(byte_for_channel * num_data_channels,
                                           GFP_KERNEL);
-                       if (!rx_array) {
-                               len = -ENOMEM;
-                               goto st_sensors_free_memory;
-                       }
+                       if (!rx_array)
+                               return -ENOMEM;
 
                        len = sdata->tf->read_multiple_byte(&sdata->tb,
                                sdata->dev, addr[0],
@@ -69,7 +61,7 @@ int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
                                rx_array, sdata->multiread_bit);
                        if (len < 0) {
                                kfree(rx_array);
-                               goto st_sensors_free_memory;
+                               return len;
                        }
 
                        for (i = 0; i < n * byte_for_channel; i++) {
@@ -88,17 +80,11 @@ int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
                        buf, sdata->multiread_bit);
                break;
        default:
-               len = -EINVAL;
-               goto st_sensors_free_memory;
-       }
-       if (len != byte_for_channel * n) {
-               len = -EIO;
-               goto st_sensors_free_memory;
+               return -EINVAL;
        }
+       if (len != byte_for_channel * n)
+               return -EIO;
 
-st_sensors_free_memory:
-       kfree(addr);
-st_sensors_get_buffer_element_error:
        return len;
 }
 EXPORT_SYMBOL(st_sensors_get_buffer_element);