2018-06-12 03:33:23

by Zhouyang Jia

Subject: [PATCH] hwmon: (w83792d) add error handling for i2c_new_dummy

When i2c_new_dummy fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling i2c_new_dummy.

Signed-off-by: Zhouyang Jia <[email protected]>
---
drivers/hwmon/w83792d.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/w83792d.c b/drivers/hwmon/w83792d.c
index 76aa39e..2c168c5 100644
--- a/drivers/hwmon/w83792d.c
+++ b/drivers/hwmon/w83792d.c
@@ -961,8 +961,15 @@ w83792d_detect_subclients(struct i2c_client *new_client)
}

val = w83792d_read_value(new_client, W83792D_REG_I2C_SUBADDR);
- if (!(val & 0x08))
+ if (!(val & 0x08)) {
data->lm75[0] = i2c_new_dummy(adapter, 0x48 + (val & 0x7));
+ if (data->lm75[0] == NULL) {
+ dev_err(&new_client->dev,
+ "Failed to allocate I2C device\n");
+ err = -ENODEV;
+ goto ERROR_SC_1;
+ }
+ }
if (!(val & 0x80)) {
if ((data->lm75[0] != NULL) &&
((val & 0x7) == ((val >> 4) & 0x7))) {
@@ -974,6 +981,12 @@ w83792d_detect_subclients(struct i2c_client *new_client)
}
data->lm75[1] = i2c_new_dummy(adapter,
0x48 + ((val >> 4) & 0x7));
+ if (data->lm75[1] == NULL) {
+ dev_err(&new_client->dev,
+ "Failed to allocate I2C device\n");
+ err = -ENODEV;
+ goto ERROR_SC_1;
+ }
}

return 0;
--
2.7.4

2018-06-12 13:21:27

by Guenter Roeck

Subject: Re: [PATCH] hwmon: (w83792d) add error handling for i2c_new_dummy

On 06/11/2018 08:31 PM, Zhouyang Jia wrote:
> When i2c_new_dummy fails, the lack of error-handling code may
> cause unexpected results.
>

What are those unexpected results ? The i2c devicees are not really used;
the only reason to allocate them was for address reservation purposes.
This is why the result was ignored, since it does not really matter
for driver operation. I don't see the point of making that fatal.

NACK, sorry.

Guenter

> This patch adds error-handling code after calling i2c_new_dummy.
>
> Signed-off-by: Zhouyang Jia <[email protected]>
> ---
> drivers/hwmon/w83792d.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/w83792d.c b/drivers/hwmon/w83792d.c
> index 76aa39e..2c168c5 100644
> --- a/drivers/hwmon/w83792d.c
> +++ b/drivers/hwmon/w83792d.c
> @@ -961,8 +961,15 @@ w83792d_detect_subclients(struct i2c_client *new_client)
> }
>
> val = w83792d_read_value(new_client, W83792D_REG_I2C_SUBADDR);
> - if (!(val & 0x08))
> + if (!(val & 0x08)) {
> data->lm75[0] = i2c_new_dummy(adapter, 0x48 + (val & 0x7));
> + if (data->lm75[0] == NULL) {
> + dev_err(&new_client->dev,
> + "Failed to allocate I2C device\n");
> + err = -ENODEV;
> + goto ERROR_SC_1;
> + }
> + }
> if (!(val & 0x80)) {
> if ((data->lm75[0] != NULL) &&
> ((val & 0x7) == ((val >> 4) & 0x7))) {
> @@ -974,6 +981,12 @@ w83792d_detect_subclients(struct i2c_client *new_client)
> }
> data->lm75[1] = i2c_new_dummy(adapter,
> 0x48 + ((val >> 4) & 0x7));
> + if (data->lm75[1] == NULL) {
> + dev_err(&new_client->dev,
> + "Failed to allocate I2C device\n");
> + err = -ENODEV;
> + goto ERROR_SC_1;
> + }
> }
>
> return 0;
>