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authorJavier Martinez Canillas <javier.martinez@collabora.co.uk>2015-06-09 13:04:42 +0200
committerLee Jones <lee.jones@linaro.org>2015-06-15 13:18:19 +0100
commita841178445bb72a3d566b4e6ab9d19e9b002eb47 (patch)
treebdc857e82c9c9e8b49bd5471efa5a954673d58f0 /drivers/i2c
parentbb03ffb96c72418d06e75c7b74ea62e04c78d322 (diff)
downloadlinux-a841178445bb72a3d566b4e6ab9d19e9b002eb47.tar.bz2
mfd: cros_ec: Use a zero-length array for command data
Commit 1b84f2a4cd4a ("mfd: cros_ec: Use fixed size arrays to transfer data with the EC") modified the struct cros_ec_command fields to not use pointers for the input and output buffers and use fixed length arrays instead. This change was made because the cros_ec ioctl API uses that struct cros_ec_command to allow user-space to send commands to the EC and to get data from the EC. So using pointers made the API not 64-bit safe. Unfortunately this approach was not flexible enough for all the use-cases since there may be a need to send larger commands on newer versions of the EC command protocol. So to avoid to choose a constant length that it may be too big for most commands and thus wasting memory and CPU cycles on copy from and to user-space or having a size that is too small for some big commands, use a zero-length array that is both 64-bit safe and flexible. The same buffer is used for both output and input data so the maximum of these values should be used to allocate it. Suggested-by: Gwendal Grignou <gwendal@chromium.org> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> Tested-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Lee Jones <lee.jones@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-cros-ec-tunnel.c45
1 files changed, 30 insertions, 15 deletions
diff --git a/drivers/i2c/busses/i2c-cros-ec-tunnel.c b/drivers/i2c/busses/i2c-cros-ec-tunnel.c
index fa8dedd8c3a2..a0d95ff682ae 100644
--- a/drivers/i2c/busses/i2c-cros-ec-tunnel.c
+++ b/drivers/i2c/busses/i2c-cros-ec-tunnel.c
@@ -182,8 +182,9 @@ static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
const u16 bus_num = bus->remote_bus;
int request_len;
int response_len;
+ int alloc_size;
int result;
- struct cros_ec_command msg = { };
+ struct cros_ec_command *msg;
request_len = ec_i2c_count_message(i2c_msgs, num);
if (request_len < 0) {
@@ -198,25 +199,39 @@ static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
return response_len;
}
- result = ec_i2c_construct_message(msg.outdata, i2c_msgs, num, bus_num);
- if (result)
- return result;
+ alloc_size = max(request_len, response_len);
+ msg = kmalloc(sizeof(*msg) + alloc_size, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
- msg.version = 0;
- msg.command = EC_CMD_I2C_PASSTHRU;
- msg.outsize = request_len;
- msg.insize = response_len;
+ result = ec_i2c_construct_message(msg->data, i2c_msgs, num, bus_num);
+ if (result) {
+ dev_err(dev, "Error constructing EC i2c message %d\n", result);
+ goto exit;
+ }
- result = cros_ec_cmd_xfer(bus->ec, &msg);
- if (result < 0)
- return result;
+ msg->version = 0;
+ msg->command = EC_CMD_I2C_PASSTHRU;
+ msg->outsize = request_len;
+ msg->insize = response_len;
- result = ec_i2c_parse_response(msg.indata, i2c_msgs, &num);
- if (result < 0)
- return result;
+ result = cros_ec_cmd_xfer(bus->ec, msg);
+ if (result < 0) {
+ dev_err(dev, "Error transferring EC i2c message %d\n", result);
+ goto exit;
+ }
+
+ result = ec_i2c_parse_response(msg->data, i2c_msgs, &num);
+ if (result < 0) {
+ dev_err(dev, "Error parsing EC i2c message %d\n", result);
+ goto exit;
+ }
/* Indicate success by saying how many messages were sent */
- return num;
+ result = num;
+exit:
+ kfree(msg);
+ return result;
}
static u32 ec_i2c_functionality(struct i2c_adapter *adap)