Am 08.09.2017 12:53, schrieb Dan Carpenter:
> The background of this code is that we can either use the default
> tables or load our own table with sysfs. The default tables are three
> element arrays of struct tsl2x7x_lux. If we load the table with sysfs
> then we can have as many as nine elements. Which ever way we do it, the
> last element is always zeroed out.
>
> The most interesting part of this patch is in the
> in_illuminance0_lux_table_show() function. We were using the wrong
> limit, "TSL2X7X_MAX_LUX_TABLE_SIZE * 3", when it should have been just
> "TSL2X7X_MAX_LUX_TABLE_SIZE". This creates a static checker warning
> that we are going of of bounds. However, since the last element is
> always zeroed out, that means we hit the break statement and the code
> works correctly despite the wrong limit check.
>
> I made several related readability changes. The most notable that I
> changed the MAX_DEFAULT_TABLE_BYTES define which was:
>
> #define MAX_DEFAULT_TABLE_BYTES (sizeof(int) * TSL2X7X_MAX_LUX_TABLE_SIZE)
>
> I renamed the define to TSL2X7X_DEFAULT_TABLE_BYTES because it's not the
> max size, it's the only size. Also the size should really be expressed
> as sizeof(struct tsl2x7x_lux) * 3. In other words, 12 * 3 instead of
> 4 * 9. It's 36 bytes either way, so this doesn't change the behavior.
>
> Finally, I created the TSL2X7X_DEF_LUX_TABLE_SZ define instead of using
> the magic number 3. I declared the default tables using that define
> to hopefully signal to future programmers that if they want to use a
> different size they have to update all the related code.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> diff --git a/drivers/staging/iio/light/tsl2x7x.h b/drivers/staging/iio/light/tsl2x7x.h
> index ecae92211216..a216c6943a84 100644
> --- a/drivers/staging/iio/light/tsl2x7x.h
> +++ b/drivers/staging/iio/light/tsl2x7x.h
> @@ -23,10 +23,6 @@
> #define __TSL2X7X_H
> #include <linux/pm.h>
>
> -/* Max number of segments allowable in LUX table */
> -#define TSL2X7X_MAX_LUX_TABLE_SIZE 9
> -#define MAX_DEFAULT_TABLE_BYTES (sizeof(int) * TSL2X7X_MAX_LUX_TABLE_SIZE)
> -
> struct iio_dev;
>
> struct tsl2x7x_lux {
> @@ -35,6 +31,13 @@ struct tsl2x7x_lux {
> unsigned int ch1;
> };
>
> +/* Max number of segments allowable in LUX table */
> +#define TSL2X7X_MAX_LUX_TABLE_SIZE 9
> +/* The default LUX tables all have 3 elements. */
> +#define TSL2X7X_DEF_LUX_TABLE_SZ 3
> +#define TSL2X7X_DEFAULT_TABLE_BYTES (sizeof(struct tsl2x7x_lux) * \
> + TSL2X7X_DEF_LUX_TABLE_SZ)
> +
> /**
> * struct tsl2x7x_default_settings - power on defaults unless
> * overridden by platform data.
> diff --git a/drivers/staging/iio/light/tsl2x7x.c b/drivers/staging/iio/light/tsl2x7x.c
> index 786e93f16ce9..b3a9efecf536 100644
> --- a/drivers/staging/iio/light/tsl2x7x.c
> +++ b/drivers/staging/iio/light/tsl2x7x.c
> @@ -192,25 +192,25 @@ struct tsl2X7X_chip {
> };
>
> /* Different devices require different coefficents */
> -static const struct tsl2x7x_lux tsl2x71_lux_table[] = {
> +static const struct tsl2x7x_lux tsl2x71_lux_table[TSL2X7X_DEF_LUX_TABLE_SZ] = {
> { 14461, 611, 1211 },
> { 18540, 352, 623 },
> { 0, 0, 0 },
> };
>
> -static const struct tsl2x7x_lux tmd2x71_lux_table[] = {
> +static const struct tsl2x7x_lux tmd2x71_lux_table[TSL2X7X_DEF_LUX_TABLE_SZ] = {
> { 11635, 115, 256 },
> { 15536, 87, 179 },
> { 0, 0, 0 },
> };
>
> -static const struct tsl2x7x_lux tsl2x72_lux_table[] = {
> +static const struct tsl2x7x_lux tsl2x72_lux_table[TSL2X7X_DEF_LUX_TABLE_SZ] = {
> { 14013, 466, 917 },
> { 18222, 310, 552 },
> { 0, 0, 0 },
> };
>
> -static const struct tsl2x7x_lux tmd2x72_lux_table[] = {
> +static const struct tsl2x7x_lux tmd2x72_lux_table[TSL2X7X_DEF_LUX_TABLE_SZ] = {
> { 13218, 130, 262 },
> { 17592, 92, 169 },
> { 0, 0, 0 },
> @@ -530,7 +530,7 @@ static void tsl2x7x_defaults(struct tsl2X7X_chip *chip)
> else
> memcpy(chip->tsl2x7x_device_lux,
> (struct tsl2x7x_lux *)tsl2x7x_default_lux_table_group[chip->id],
> - MAX_DEFAULT_TABLE_BYTES);
> + TSL2X7X_DEFAULT_TABLE_BYTES);
> }
>
> /**
> @@ -1113,7 +1113,7 @@ static ssize_t in_illuminance0_lux_table_show(struct device *dev,
> int i = 0;
> int offset = 0;
>
> - while (i < (TSL2X7X_MAX_LUX_TABLE_SIZE * 3)) {
> + while (i < TSL2X7X_MAX_LUX_TABLE_SIZE) {
> offset += snprintf(buf + offset, PAGE_SIZE, "%u,%u,%u,",
> chip->tsl2x7x_device_lux[i].ratio,
> chip->tsl2x7x_device_lux[i].ch0,
Is that TSL2X7X_MAX_LUX_TABLE_SIZE needed at all ? because:
if (chip->tsl2x7x_device_lux[i].ratio == 0) ... break;
So its only needed for protection agains faulty updates. (maybe i missed an other use).
NTL so far i see the user will always get something like:
14013, 466, 917, 15536, 87, 179 , 0, 0, 0
are the last three 0 need for something ? compatibility ? otherwise i would suggest
something like:
for (i=0;
chip->tsl2x7x_device_lux[i].ratio != 0;
i++)
snprintf() ...
just my 2 cents,
re
wh
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
