On Fri, 22 May 2015, Javier Martinez Canillas wrote:

> 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 <[email protected]>
> Signed-off-by: Javier Martinez Canillas <[email protected]>
> Tested-by: Heiko Stuebner <[email protected]>
> ---
> 
> Changes since v2:
>  - Set the version field in the cros_ec_command. Reported by Heiko Stuebner
>  - Use kmalloc/kfree instead of pre-allocating using variables in the stack.
>    Suggested by Lee Jones.
> 
> Changes since v1:
>  - Add Heiko Stuebner Tested-by tag
>  - Removed a new blank line at EOF warning. Reported by Heiko Stuebner
>  - Use kmalloc instead of kzalloc when the message is later initialized
>    Suggested by Gwendal Grignou
>  - Pre-allocate struct cros_ec_command instead of dynamically allocate it
>    whenever is possible. Suggested by Gwendal Grignou
>  - Pre-allocate buffers for the usual cases and only allocate dynamically
>    in the heap for bigger sizes. Suggested by Gwendal Grignou
>  - Don't access the cros_ec_command received from user-space before doing
>    a copy_from_user. Suggested by Gwendal Grignou
>  - Only copy from user-space outsize bytes and copy_to_user insize bytes
>    Suggested by Gwendal Grignou
>  - ec_device_ioctl_xcmd() must return the numbers of bytes read and not 0
>    on success. Suggested by Gwendal Grignou
>  - Rename alloc_cmd_msg to alloc_lightbar_cmd_msg. Suggested by Gwendal 
> Grignou
> ---
>  drivers/i2c/busses/i2c-cros-ec-tunnel.c    |  45 ++++++---
>  drivers/input/keyboard/cros_ec_keyb.c      |  29 ++++--
>  drivers/mfd/cros_ec.c                      |  28 ++++--
>  drivers/mfd/cros_ec_i2c.c                  |   4 +-
>  drivers/mfd/cros_ec_spi.c                  |   2 +-

For the MFD changes:
 Acked-by: Lee Jones <[email protected]>

>  drivers/platform/chrome/cros_ec_dev.c      |  65 +++++++-----
>  drivers/platform/chrome/cros_ec_lightbar.c | 152 +++++++++++++++++++---------
>  drivers/platform/chrome/cros_ec_lpc.c      |   8 +-
>  drivers/platform/chrome/cros_ec_sysfs.c    | 154 
> ++++++++++++++++++-----------
>  include/linux/mfd/cros_ec.h                |   6 +-
>  10 files changed, 318 insertions(+), 175 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)
> diff --git a/drivers/input/keyboard/cros_ec_keyb.c 
> b/drivers/input/keyboard/cros_ec_keyb.c
> index b50c5b8b8a4d..974154a74505 100644
> --- a/drivers/input/keyboard/cros_ec_keyb.c
> +++ b/drivers/input/keyboard/cros_ec_keyb.c
> @@ -148,19 +148,28 @@ static void cros_ec_keyb_process(struct cros_ec_keyb 
> *ckdev,
>  
>  static int cros_ec_keyb_get_state(struct cros_ec_keyb *ckdev, uint8_t 
> *kb_state)
>  {
> -     int ret;
> -     struct cros_ec_command msg = {
> -             .command = EC_CMD_MKBP_STATE,
> -             .insize = ckdev->cols,
> -     };
> +     int ret = 0;
> +     struct cros_ec_command *msg;
>  
> -     ret = cros_ec_cmd_xfer(ckdev->ec, &msg);
> -     if (ret < 0)
> -             return ret;
> +     msg = kmalloc(sizeof(*msg) + ckdev->cols, GFP_KERNEL);
> +     if (!msg)
> +             return -ENOMEM;
>  
> -     memcpy(kb_state, msg.indata, ckdev->cols);
> +     msg->version = 0;
> +     msg->command = EC_CMD_MKBP_STATE;
> +     msg->insize = ckdev->cols;
> +     msg->outsize = 0;
>  
> -     return 0;
> +     ret = cros_ec_cmd_xfer(ckdev->ec, msg);
> +     if (ret < 0) {
> +             dev_err(ckdev->dev, "Error transferring EC message %d\n", ret);
> +             goto exit;
> +     }
> +
> +     memcpy(kb_state, msg->data, ckdev->cols);
> +exit:
> +     kfree(msg);
> +     return ret;
>  }
>  
>  static irqreturn_t cros_ec_keyb_irq(int irq, void *data)
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index 1574a9352a6d..4a0f6dfcd376 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -41,7 +41,7 @@ int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
>       out[2] = msg->outsize;
>       csum = out[0] + out[1] + out[2];
>       for (i = 0; i < msg->outsize; i++)
> -             csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->outdata[i];
> +             csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
>       out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = (uint8_t)(csum & 0xff);
>  
>       return EC_MSG_TX_PROTO_BYTES + msg->outsize;
> @@ -75,11 +75,20 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
>       ret = ec_dev->cmd_xfer(ec_dev, msg);
>       if (msg->result == EC_RES_IN_PROGRESS) {
>               int i;
> -             struct cros_ec_command status_msg = { };
> +             struct cros_ec_command *status_msg;
>               struct ec_response_get_comms_status *status;
>  
> -             status_msg.command = EC_CMD_GET_COMMS_STATUS;
> -             status_msg.insize = sizeof(*status);
> +             status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
> +                                  GFP_KERNEL);
> +             if (!status_msg) {
> +                     ret = -ENOMEM;
> +                     goto exit;
> +             }
> +
> +             status_msg->version = 0;
> +             status_msg->command = EC_CMD_GET_COMMS_STATUS;
> +             status_msg->insize = sizeof(*status);
> +             status_msg->outsize = 0;
>  
>               /*
>                * Query the EC's status until it's no longer busy or
> @@ -88,20 +97,23 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
>               for (i = 0; i < EC_COMMAND_RETRIES; i++) {
>                       usleep_range(10000, 11000);
>  
> -                     ret = ec_dev->cmd_xfer(ec_dev, &status_msg);
> +                     ret = ec_dev->cmd_xfer(ec_dev, status_msg);
>                       if (ret < 0)
>                               break;
>  
> -                     msg->result = status_msg.result;
> -                     if (status_msg.result != EC_RES_SUCCESS)
> +                     msg->result = status_msg->result;
> +                     if (status_msg->result != EC_RES_SUCCESS)
>                               break;
>  
>                       status = (struct ec_response_get_comms_status *)
> -                              status_msg.indata;
> +                              status_msg->data;
>                       if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
>                               break;
>               }
> +
> +             kfree(status_msg);
>       }
> +exit:
>       mutex_unlock(&ec_dev->lock);
>  
>       return ret;
> diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
> index 82b4d6148698..fbf7819f5de5 100644
> --- a/drivers/mfd/cros_ec_i2c.c
> +++ b/drivers/mfd/cros_ec_i2c.c
> @@ -76,7 +76,7 @@ static int cros_ec_cmd_xfer_i2c(struct cros_ec_device 
> *ec_dev,
>       /* copy message payload and compute checksum */
>       sum = out_buf[0] + out_buf[1] + out_buf[2];
>       for (i = 0; i < msg->outsize; i++) {
> -             out_buf[3 + i] = msg->outdata[i];
> +             out_buf[3 + i] = msg->data[i];
>               sum += out_buf[3 + i];
>       }
>       out_buf[3 + msg->outsize] = sum;
> @@ -109,7 +109,7 @@ static int cros_ec_cmd_xfer_i2c(struct cros_ec_device 
> *ec_dev,
>       /* copy response packet payload and compute checksum */
>       sum = in_buf[0] + in_buf[1];
>       for (i = 0; i < len; i++) {
> -             msg->indata[i] = in_buf[2 + i];
> +             msg->data[i] = in_buf[2 + i];
>               sum += in_buf[2 + i];
>       }
>       dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
> diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
> index 27bd52e5e8b7..573730fec947 100644
> --- a/drivers/mfd/cros_ec_spi.c
> +++ b/drivers/mfd/cros_ec_spi.c
> @@ -299,7 +299,7 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device 
> *ec_dev,
>       for (i = 0; i < len; i++) {
>               sum += ptr[i + 2];
>               if (ec_msg->insize)
> -                     ec_msg->indata[i] = ptr[i + 2];
> +                     ec_msg->data[i] = ptr[i + 2];
>       }
>       sum &= 0xff;
>  
> diff --git a/drivers/platform/chrome/cros_ec_dev.c 
> b/drivers/platform/chrome/cros_ec_dev.c
> index 6090d0b2826f..e91ced1cb8ce 100644
> --- a/drivers/platform/chrome/cros_ec_dev.c
> +++ b/drivers/platform/chrome/cros_ec_dev.c
> @@ -20,6 +20,7 @@
>  #include <linux/fs.h>
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
> +#include <linux/slab.h>
>  #include <linux/uaccess.h>
>  
>  #include "cros_ec_dev.h"
> @@ -36,28 +37,31 @@ static int ec_get_version(struct cros_ec_device *ec, char 
> *str, int maxlen)
>       static const char * const current_image_name[] = {
>               "unknown", "read-only", "read-write", "invalid",
>       };
> -     struct cros_ec_command msg = {
> -             .version = 0,
> -             .command = EC_CMD_GET_VERSION,
> -             .outdata = { 0 },
> -             .outsize = 0,
> -             .indata = { 0 },
> -             .insize = sizeof(*resp),
> -     };
> +     struct cros_ec_command *msg;
>       int ret;
>  
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     msg = kmalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
> +     if (!msg)
> +             return -ENOMEM;
> +
> +     msg->version = 0;
> +     msg->command = EC_CMD_GET_VERSION;
> +     msg->insize = sizeof(*resp);
> +     msg->outsize = 0;
> +
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
> -             return ret;
> +             goto exit;
>  
> -     if (msg.result != EC_RES_SUCCESS) {
> +     if (msg->result != EC_RES_SUCCESS) {
>               snprintf(str, maxlen,
>                        "%s\nUnknown EC version: EC returned %d\n",
> -                      CROS_EC_DEV_VERSION, msg.result);
> -             return 0;
> +                      CROS_EC_DEV_VERSION, msg->result);
> +             ret = -EINVAL;
> +             goto exit;
>       }
>  
> -     resp = (struct ec_response_get_version *)msg.indata;
> +     resp = (struct ec_response_get_version *)msg->data;
>       if (resp->current_image >= ARRAY_SIZE(current_image_name))
>               resp->current_image = 3; /* invalid */
>  
> @@ -65,7 +69,10 @@ static int ec_get_version(struct cros_ec_device *ec, char 
> *str, int maxlen)
>                resp->version_string_ro, resp->version_string_rw,
>                current_image_name[resp->current_image]);
>  
> -     return 0;
> +     ret = 0;
> +exit:
> +     kfree(msg);
> +     return ret;
>  }
>  
>  /* Device file ops */
> @@ -110,20 +117,32 @@ static ssize_t ec_device_read(struct file *filp, char 
> __user *buffer,
>  static long ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg)
>  {
>       long ret;
> -     struct cros_ec_command s_cmd = { };
> +     struct cros_ec_command u_cmd;
> +     struct cros_ec_command *s_cmd;
>  
> -     if (copy_from_user(&s_cmd, arg, sizeof(s_cmd)))
> +     if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
>               return -EFAULT;
>  
> -     ret = cros_ec_cmd_xfer(ec, &s_cmd);
> +     s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
> +                     GFP_KERNEL);
> +     if (!s_cmd)
> +             return -ENOMEM;
> +
> +     if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
> +             ret = -EFAULT;
> +             goto exit;
> +     }
> +
> +     ret = cros_ec_cmd_xfer(ec, s_cmd);
>       /* Only copy data to userland if data was received. */
>       if (ret < 0)
> -             return ret;
> +             goto exit;
>  
> -     if (copy_to_user(arg, &s_cmd, sizeof(s_cmd)))
> -             return -EFAULT;
> -
> -     return 0;
> +     if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize))
> +             ret = -EFAULT;
> +exit:
> +     kfree(s_cmd);
> +     return ret;
>  }
>  
>  static long ec_device_ioctl_readmem(struct cros_ec_device *ec, void __user 
> *arg)
> diff --git a/drivers/platform/chrome/cros_ec_lightbar.c 
> b/drivers/platform/chrome/cros_ec_lightbar.c
> index b4ff47a9069a..560e5d41b7ae 100644
> --- a/drivers/platform/chrome/cros_ec_lightbar.c
> +++ b/drivers/platform/chrome/cros_ec_lightbar.c
> @@ -31,6 +31,7 @@
>  #include <linux/sched.h>
>  #include <linux/types.h>
>  #include <linux/uaccess.h>
> +#include <linux/slab.h>
>  
>  #include "cros_ec_dev.h"
>  
> @@ -91,54 +92,79 @@ out:
>       return ret;
>  }
>  
> -#define INIT_MSG(P, R) { \
> -             .command = EC_CMD_LIGHTBAR_CMD, \
> -             .outsize = sizeof(*P), \
> -             .insize = sizeof(*R), \
> -     }
> +static struct cros_ec_command *alloc_lightbar_cmd_msg(void)
> +{
> +     struct cros_ec_command *msg;
> +     int len;
> +
> +     len = max(sizeof(struct ec_params_lightbar),
> +               sizeof(struct ec_response_lightbar));
> +
> +     msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
> +     if (!msg)
> +             return NULL;
> +
> +     msg->version = 0;
> +     msg->command = EC_CMD_LIGHTBAR_CMD;
> +     msg->outsize = sizeof(struct ec_params_lightbar);
> +     msg->insize = sizeof(struct ec_response_lightbar);
> +
> +     return msg;
> +}
>  
>  static int get_lightbar_version(struct cros_ec_device *ec,
>                               uint32_t *ver_ptr, uint32_t *flg_ptr)
>  {
>       struct ec_params_lightbar *param;
>       struct ec_response_lightbar *resp;
> -     struct cros_ec_command msg = INIT_MSG(param, resp);
> +     struct cros_ec_command *msg;
>       int ret;
>  
> -     param = (struct ec_params_lightbar *)msg.outdata;
> -     param->cmd = LIGHTBAR_CMD_VERSION;
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> -     if (ret < 0)
> +     msg = alloc_lightbar_cmd_msg();
> +     if (!msg)
>               return 0;
>  
> -     switch (msg.result) {
> +     param = (struct ec_params_lightbar *)msg->data;
> +     param->cmd = LIGHTBAR_CMD_VERSION;
> +     ret = cros_ec_cmd_xfer(ec, msg);
> +     if (ret < 0) {
> +             ret = 0;
> +             goto exit;
> +     }
> +
> +     switch (msg->result) {
>       case EC_RES_INVALID_PARAM:
>               /* Pixel had no version command. */
>               if (ver_ptr)
>                       *ver_ptr = 0;
>               if (flg_ptr)
>                       *flg_ptr = 0;
> -             return 1;
> +             ret = 1;
> +             goto exit;
>  
>       case EC_RES_SUCCESS:
> -             resp = (struct ec_response_lightbar *)msg.indata;
> +             resp = (struct ec_response_lightbar *)msg->data;
>  
>               /* Future devices w/lightbars should implement this command */
>               if (ver_ptr)
>                       *ver_ptr = resp->version.num;
>               if (flg_ptr)
>                       *flg_ptr = resp->version.flags;
> -             return 1;
> +             ret = 1;
> +             goto exit;
>       }
>  
>       /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
> -     return 0;
> +     ret = 0;
> +exit:
> +     kfree(msg);
> +     return ret;
>  }
>  
>  static ssize_t version_show(struct device *dev,
>                           struct device_attribute *attr, char *buf)
>  {
> -     uint32_t version, flags;
> +     uint32_t version = 0, flags = 0;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>       int ret;
>  
> @@ -158,8 +184,7 @@ static ssize_t brightness_store(struct device *dev,
>                               const char *buf, size_t count)
>  {
>       struct ec_params_lightbar *param;
> -     struct ec_response_lightbar *resp;
> -     struct cros_ec_command msg = INIT_MSG(param, resp);
> +     struct cros_ec_command *msg;
>       int ret;
>       unsigned int val;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
> @@ -167,21 +192,30 @@ static ssize_t brightness_store(struct device *dev,
>       if (kstrtouint(buf, 0, &val))
>               return -EINVAL;
>  
> -     param = (struct ec_params_lightbar *)msg.outdata;
> +     msg = alloc_lightbar_cmd_msg();
> +     if (!msg)
> +             return -ENOMEM;
> +
> +     param = (struct ec_params_lightbar *)msg->data;
>       param->cmd = LIGHTBAR_CMD_BRIGHTNESS;
>       param->brightness.num = val;
>       ret = lb_throttle();
>       if (ret)
> -             return ret;
> +             goto exit;
>  
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
> -             return ret;
> +             goto exit;
>  
> -     if (msg.result != EC_RES_SUCCESS)
> -             return -EINVAL;
> +     if (msg->result != EC_RES_SUCCESS) {
> +             ret = -EINVAL;
> +             goto exit;
> +     }
>  
> -     return count;
> +     ret = count;
> +exit:
> +     kfree(msg);
> +     return ret;
>  }
>  
>  
> @@ -196,12 +230,15 @@ static ssize_t led_rgb_store(struct device *dev, struct 
> device_attribute *attr,
>                            const char *buf, size_t count)
>  {
>       struct ec_params_lightbar *param;
> -     struct ec_response_lightbar *resp;
> -     struct cros_ec_command msg = INIT_MSG(param, resp);
> +     struct cros_ec_command *msg;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>       unsigned int val[4];
>       int ret, i = 0, j = 0, ok = 0;
>  
> +     msg = alloc_lightbar_cmd_msg();
> +     if (!msg)
> +             return -ENOMEM;
> +
>       do {
>               /* Skip any whitespace */
>               while (*buf && isspace(*buf))
> @@ -215,7 +252,7 @@ static ssize_t led_rgb_store(struct device *dev, struct 
> device_attribute *attr,
>                       return -EINVAL;
>  
>               if (i == 4) {
> -                     param = (struct ec_params_lightbar *)msg.outdata;
> +                     param = (struct ec_params_lightbar *)msg->data;
>                       param->cmd = LIGHTBAR_CMD_RGB;
>                       param->rgb.led = val[0];
>                       param->rgb.red = val[1];
> @@ -231,12 +268,14 @@ static ssize_t led_rgb_store(struct device *dev, struct 
> device_attribute *attr,
>                                       return ret;
>                       }
>  
> -                     ret = cros_ec_cmd_xfer(ec, &msg);
> +                     ret = cros_ec_cmd_xfer(ec, msg);
>                       if (ret < 0)
> -                             return ret;
> +                             goto exit;
>  
> -                     if (msg.result != EC_RES_SUCCESS)
> -                             return -EINVAL;
> +                     if (msg->result != EC_RES_SUCCESS) {
> +                             ret = -EINVAL;
> +                             goto exit;
> +                     }
>  
>                       i = 0;
>                       ok = 1;
> @@ -248,6 +287,8 @@ static ssize_t led_rgb_store(struct device *dev, struct 
> device_attribute *attr,
>  
>       } while (*buf);
>  
> +exit:
> +     kfree(msg);
>       return (ok && i == 0) ? count : -EINVAL;
>  }
>  
> @@ -261,42 +302,55 @@ static ssize_t sequence_show(struct device *dev,
>  {
>       struct ec_params_lightbar *param;
>       struct ec_response_lightbar *resp;
> -     struct cros_ec_command msg = INIT_MSG(param, resp);
> +     struct cros_ec_command *msg;
>       int ret;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>  
> -     param = (struct ec_params_lightbar *)msg.outdata;
> +     msg = alloc_lightbar_cmd_msg();
> +     if (!msg)
> +             return -ENOMEM;
> +
> +     param = (struct ec_params_lightbar *)msg->data;
>       param->cmd = LIGHTBAR_CMD_GET_SEQ;
>       ret = lb_throttle();
>       if (ret)
> -             return ret;
> +             goto exit;
>  
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
> -             return ret;
> +             goto exit;
>  
> -     if (msg.result != EC_RES_SUCCESS)
> -             return scnprintf(buf, PAGE_SIZE,
> -                              "ERROR: EC returned %d\n", msg.result);
> +     if (msg->result != EC_RES_SUCCESS) {
> +             ret = scnprintf(buf, PAGE_SIZE,
> +                             "ERROR: EC returned %d\n", msg->result);
> +             goto exit;
> +     }
>  
> -     resp = (struct ec_response_lightbar *)msg.indata;
> +     resp = (struct ec_response_lightbar *)msg->data;
>       if (resp->get_seq.num >= ARRAY_SIZE(seqname))
> -             return scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
> +             ret = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
>       else
> -             return scnprintf(buf, PAGE_SIZE, "%s\n",
> -                              seqname[resp->get_seq.num]);
> +             ret = scnprintf(buf, PAGE_SIZE, "%s\n",
> +                             seqname[resp->get_seq.num]);
> +
> +exit:
> +     kfree(msg);
> +     return ret;
>  }
>  
>  static ssize_t sequence_store(struct device *dev, struct device_attribute 
> *attr,
>                             const char *buf, size_t count)
>  {
>       struct ec_params_lightbar *param;
> -     struct ec_response_lightbar *resp;
> -     struct cros_ec_command msg = INIT_MSG(param, resp);
> +     struct cros_ec_command *msg;
>       unsigned int num;
>       int ret, len;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>  
> +     msg = alloc_lightbar_cmd_msg();
> +     if (!msg)
> +             return -ENOMEM;
> +
>       for (len = 0; len < count; len++)
>               if (!isalnum(buf[len]))
>                       break;
> @@ -311,18 +365,18 @@ static ssize_t sequence_store(struct device *dev, 
> struct device_attribute *attr,
>                       return ret;
>       }
>  
> -     param = (struct ec_params_lightbar *)msg.outdata;
> +     param = (struct ec_params_lightbar *)msg->data;
>       param->cmd = LIGHTBAR_CMD_SEQ;
>       param->seq.num = num;
>       ret = lb_throttle();
>       if (ret)
>               return ret;
>  
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
>               return ret;
>  
> -     if (msg.result != EC_RES_SUCCESS)
> +     if (msg->result != EC_RES_SUCCESS)
>               return -EINVAL;
>  
>       return count;
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c 
> b/drivers/platform/chrome/cros_ec_lpc.c
> index 860310513cf0..4c7f0df33bf8 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -73,8 +73,8 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
>  
>       /* Copy data and update checksum */
>       for (i = 0; i < msg->outsize; i++) {
> -             outb(msg->outdata[i], EC_LPC_ADDR_HOST_PARAM + i);
> -             csum += msg->outdata[i];
> +             outb(msg->data[i], EC_LPC_ADDR_HOST_PARAM + i);
> +             csum += msg->data[i];
>       }
>  
>       /* Finalize checksum and write args */
> @@ -129,8 +129,8 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
>  
>       /* Read response and update checksum */
>       for (i = 0; i < args.data_size; i++) {
> -             msg->indata[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
> -             csum += msg->indata[i];
> +             msg->data[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
> +             csum += msg->data[i];
>       }
>  
>       /* Verify checksum */
> diff --git a/drivers/platform/chrome/cros_ec_sysfs.c 
> b/drivers/platform/chrome/cros_ec_sysfs.c
> index fb62ab6cc659..78ba82d670cb 100644
> --- a/drivers/platform/chrome/cros_ec_sysfs.c
> +++ b/drivers/platform/chrome/cros_ec_sysfs.c
> @@ -29,6 +29,7 @@
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
>  #include <linux/printk.h>
> +#include <linux/slab.h>
>  #include <linux/stat.h>
>  #include <linux/types.h>
>  #include <linux/uaccess.h>
> @@ -66,14 +67,19 @@ static ssize_t store_ec_reboot(struct device *dev,
>               {"hibernate",    EC_REBOOT_HIBERNATE, 0},
>               {"at-shutdown",  -1, EC_REBOOT_FLAG_ON_AP_SHUTDOWN},
>       };
> -     struct cros_ec_command msg = { 0 };
> -     struct ec_params_reboot_ec *param =
> -             (struct ec_params_reboot_ec *)msg.outdata;
> +     struct cros_ec_command *msg;
> +     struct ec_params_reboot_ec *param;
>       int got_cmd = 0, offset = 0;
>       int i;
>       int ret;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>  
> +     msg = kmalloc(sizeof(*msg) + sizeof(*param), GFP_KERNEL);
> +     if (!msg)
> +             return -ENOMEM;
> +
> +     param = (struct ec_params_reboot_ec *)msg->data;
> +
>       param->flags = 0;
>       while (1) {
>               /* Find word to start scanning */
> @@ -100,19 +106,26 @@ static ssize_t store_ec_reboot(struct device *dev,
>                       offset++;
>       }
>  
> -     if (!got_cmd)
> -             return -EINVAL;
> -
> -     msg.command = EC_CMD_REBOOT_EC;
> -     msg.outsize = sizeof(param);
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> -     if (ret < 0)
> -             return ret;
> -     if (msg.result != EC_RES_SUCCESS) {
> -             dev_dbg(ec->dev, "EC result %d\n", msg.result);
> -             return -EINVAL;
> +     if (!got_cmd) {
> +             count = -EINVAL;
> +             goto exit;
>       }
>  
> +     msg->version = 0;
> +     msg->command = EC_CMD_REBOOT_EC;
> +     msg->outsize = sizeof(*param);
> +     msg->insize = 0;
> +     ret = cros_ec_cmd_xfer(ec, msg);
> +     if (ret < 0) {
> +             count = ret;
> +             goto exit;
> +     }
> +     if (msg->result != EC_RES_SUCCESS) {
> +             dev_dbg(ec->dev, "EC result %d\n", msg->result);
> +             count = -EINVAL;
> +     }
> +exit:
> +     kfree(msg);
>       return count;
>  }
>  
> @@ -123,22 +136,32 @@ static ssize_t show_ec_version(struct device *dev,
>       struct ec_response_get_version *r_ver;
>       struct ec_response_get_chip_info *r_chip;
>       struct ec_response_board_version *r_board;
> -     struct cros_ec_command msg = { 0 };
> +     struct cros_ec_command *msg;
>       int ret;
>       int count = 0;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>  
> +     msg = kmalloc(sizeof(*msg) + EC_HOST_PARAM_SIZE, GFP_KERNEL);
> +     if (!msg)
> +             return -ENOMEM;
> +
>       /* Get versions. RW may change. */
> -     msg.command = EC_CMD_GET_VERSION;
> -     msg.insize = sizeof(*r_ver);
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> -     if (ret < 0)
> -             return ret;
> -     if (msg.result != EC_RES_SUCCESS)
> -             return scnprintf(buf, PAGE_SIZE,
> -                              "ERROR: EC returned %d\n", msg.result);
> +     msg->version = 0;
> +     msg->command = EC_CMD_GET_VERSION;
> +     msg->insize = sizeof(*r_ver);
> +     msg->outsize = 0;
> +     ret = cros_ec_cmd_xfer(ec, msg);
> +     if (ret < 0) {
> +             count = ret;
> +             goto exit;
> +     }
> +     if (msg->result != EC_RES_SUCCESS) {
> +             count = scnprintf(buf, PAGE_SIZE,
> +                               "ERROR: EC returned %d\n", msg->result);
> +             goto exit;
> +     }
>  
> -     r_ver = (struct ec_response_get_version *)msg.indata;
> +     r_ver = (struct ec_response_get_version *)msg->data;
>       /* Strings should be null-terminated, but let's be sure. */
>       r_ver->version_string_ro[sizeof(r_ver->version_string_ro) - 1] = '\0';
>       r_ver->version_string_rw[sizeof(r_ver->version_string_rw) - 1] = '\0';
> @@ -152,33 +175,33 @@ static ssize_t show_ec_version(struct device *dev,
>                           image_names[r_ver->current_image] : "?"));
>  
>       /* Get build info. */
> -     msg.command = EC_CMD_GET_BUILD_INFO;
> -     msg.insize = sizeof(msg.indata);
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     msg->command = EC_CMD_GET_BUILD_INFO;
> +     msg->insize = EC_HOST_PARAM_SIZE;
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
>               count += scnprintf(buf + count, PAGE_SIZE - count,
>                                  "Build info:    XFER ERROR %d\n", ret);
> -     else if (msg.result != EC_RES_SUCCESS)
> +     else if (msg->result != EC_RES_SUCCESS)
>               count += scnprintf(buf + count, PAGE_SIZE - count,
> -                                "Build info:    EC error %d\n", msg.result);
> +                                "Build info:    EC error %d\n", msg->result);
>       else {
> -             msg.indata[sizeof(msg.indata) - 1] = '\0';
> +             msg->data[sizeof(msg->data) - 1] = '\0';
>               count += scnprintf(buf + count, PAGE_SIZE - count,
> -                                "Build info:    %s\n", msg.indata);
> +                                "Build info:    %s\n", msg->data);
>       }
>  
>       /* Get chip info. */
> -     msg.command = EC_CMD_GET_CHIP_INFO;
> -     msg.insize = sizeof(*r_chip);
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     msg->command = EC_CMD_GET_CHIP_INFO;
> +     msg->insize = sizeof(*r_chip);
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
>               count += scnprintf(buf + count, PAGE_SIZE - count,
>                                  "Chip info:     XFER ERROR %d\n", ret);
> -     else if (msg.result != EC_RES_SUCCESS)
> +     else if (msg->result != EC_RES_SUCCESS)
>               count += scnprintf(buf + count, PAGE_SIZE - count,
> -                                "Chip info:     EC error %d\n", msg.result);
> +                                "Chip info:     EC error %d\n", msg->result);
>       else {
> -             r_chip = (struct ec_response_get_chip_info *)msg.indata;
> +             r_chip = (struct ec_response_get_chip_info *)msg->data;
>  
>               r_chip->vendor[sizeof(r_chip->vendor) - 1] = '\0';
>               r_chip->name[sizeof(r_chip->name) - 1] = '\0';
> @@ -192,23 +215,25 @@ static ssize_t show_ec_version(struct device *dev,
>       }
>  
>       /* Get board version */
> -     msg.command = EC_CMD_GET_BOARD_VERSION;
> -     msg.insize = sizeof(*r_board);
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     msg->command = EC_CMD_GET_BOARD_VERSION;
> +     msg->insize = sizeof(*r_board);
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
>               count += scnprintf(buf + count, PAGE_SIZE - count,
>                                  "Board version: XFER ERROR %d\n", ret);
> -     else if (msg.result != EC_RES_SUCCESS)
> +     else if (msg->result != EC_RES_SUCCESS)
>               count += scnprintf(buf + count, PAGE_SIZE - count,
> -                                "Board version: EC error %d\n", msg.result);
> +                                "Board version: EC error %d\n", msg->result);
>       else {
> -             r_board = (struct ec_response_board_version *)msg.indata;
> +             r_board = (struct ec_response_board_version *)msg->data;
>  
>               count += scnprintf(buf + count, PAGE_SIZE - count,
>                                  "Board version: %d\n",
>                                  r_board->board_version);
>       }
>  
> +exit:
> +     kfree(msg);
>       return count;
>  }
>  
> @@ -216,27 +241,38 @@ static ssize_t show_ec_flashinfo(struct device *dev,
>                                struct device_attribute *attr, char *buf)
>  {
>       struct ec_response_flash_info *resp;
> -     struct cros_ec_command msg = { 0 };
> +     struct cros_ec_command *msg;
>       int ret;
>       struct cros_ec_device *ec = dev_get_drvdata(dev);
>  
> +     msg = kmalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
> +     if (!msg)
> +             return -ENOMEM;
> +
>       /* The flash info shouldn't ever change, but ask each time anyway. */
> -     msg.command = EC_CMD_FLASH_INFO;
> -     msg.insize = sizeof(*resp);
> -     ret = cros_ec_cmd_xfer(ec, &msg);
> +     msg->version = 0;
> +     msg->command = EC_CMD_FLASH_INFO;
> +     msg->insize = sizeof(*resp);
> +     msg->outsize = 0;
> +     ret = cros_ec_cmd_xfer(ec, msg);
>       if (ret < 0)
> -             return ret;
> -     if (msg.result != EC_RES_SUCCESS)
> -             return scnprintf(buf, PAGE_SIZE,
> -                              "ERROR: EC returned %d\n", msg.result);
> -
> -     resp = (struct ec_response_flash_info *)msg.indata;
> -
> -     return scnprintf(buf, PAGE_SIZE,
> -                      "FlashSize %d\nWriteSize %d\n"
> -                      "EraseSize %d\nProtectSize %d\n",
> -                      resp->flash_size, resp->write_block_size,
> -                      resp->erase_block_size, resp->protect_block_size);
> +             goto exit;
> +     if (msg->result != EC_RES_SUCCESS) {
> +             ret = scnprintf(buf, PAGE_SIZE,
> +                             "ERROR: EC returned %d\n", msg->result);
> +             goto exit;
> +     }
> +
> +     resp = (struct ec_response_flash_info *)msg->data;
> +
> +     ret = scnprintf(buf, PAGE_SIZE,
> +                     "FlashSize %d\nWriteSize %d\n"
> +                     "EraseSize %d\nProtectSize %d\n",
> +                     resp->flash_size, resp->write_block_size,
> +                     resp->erase_block_size, resp->protect_block_size);
> +exit:
> +     kfree(msg);
> +     return ret;
>  }
>  
>  /* Module initialization */
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 14cf522123dd..7eee38abd02a 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -42,8 +42,7 @@ enum {
>   * @outsize: Outgoing length in bytes
>   * @insize: Max number of bytes to accept from EC
>   * @result: EC's response to the command (separate from communication 
> failure)
> - * @outdata: Outgoing data to EC
> - * @indata: Where to put the incoming data from EC
> + * @data: Where to put the incoming data from EC and outgoing data to EC
>   */
>  struct cros_ec_command {
>       uint32_t version;
> @@ -51,8 +50,7 @@ struct cros_ec_command {
>       uint32_t outsize;
>       uint32_t insize;
>       uint32_t result;
> -     uint8_t outdata[EC_PROTO2_MAX_PARAM_SIZE];
> -     uint8_t indata[EC_PROTO2_MAX_PARAM_SIZE];
> +     uint8_t data[0];
>  };
>  
>  /**

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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