2018-12-25 06:25:21

by Kangjie Lu

Subject: [PATCH] backlight: (adp8870) fix a missing check for adp8870_write

adp8870_write() may fail. This fix checks if adp8870_write fails, and if
so, returns its error code.

Signed-off-by: Kangjie Lu <[email protected]>
---
drivers/video/backlight/adp8870_bl.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
index 8d50e0299578..79901fb4fcd1 100644
--- a/drivers/video/backlight/adp8870_bl.c
+++ b/drivers/video/backlight/adp8870_bl.c
@@ -811,9 +811,14 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,
if (!ret) {
reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
reg_val |= (val - 1) << CFGR_BLV_SHIFT;
- adp8870_write(data->client, ADP8870_CFGR, reg_val);
- }
- mutex_unlock(&data->lock);
+ ret = adp8870_write(data->client,
+ ADP8870_CFGR, reg_val);
+ if (ret) {
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+ } else
+ mutex_unlock(&data->lock);
}

return count;
--
2.17.2 (Apple Git-113)

2018-12-27 18:20:37

by Sam Ravnborg

Subject: Re: [PATCH] backlight: (adp8870) fix a missing check for adp8870_write

Hi Kangjie

> adp8870_write() may fail. This fix checks if adp8870_write fails, and if
> so, returns its error code.
>
> Signed-off-by: Kangjie Lu <[email protected]>
> ---
> drivers/video/backlight/adp8870_bl.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
> index 8d50e0299578..79901fb4fcd1 100644
> --- a/drivers/video/backlight/adp8870_bl.c
> +++ b/drivers/video/backlight/adp8870_bl.c
> @@ -811,9 +811,14 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,
> if (!ret) {
> reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8870_write(data->client, ADP8870_CFGR, reg_val);
> - }
> - mutex_unlock(&data->lock);
> + ret = adp8870_write(data->client,
> + ADP8870_CFGR, reg_val);
> + if (ret) {
> + mutex_unlock(&data->lock);
> + return ret;
> + }
> + } else
> + mutex_unlock(&data->lock);
> }

Something looks wrong with the indent.
If you have braces around first part of if () then use
barces also after else. Then it is easier to follow the code.
In this case please consider another approach where you
have only a single mutex_unlock() both in the good and
in the error case.

Sam

2019-01-03 23:30:42

by Daniel Thompson

Subject: Re: [PATCH] backlight: (adp8870) fix a missing check for adp8870_write

On Tue, Dec 25, 2018 at 12:21:09AM -0600, Kangjie Lu wrote:
> adp8870_write() may fail. This fix checks if adp8870_write fails, and if
> so, returns its error code.
>
> Signed-off-by: Kangjie Lu <[email protected]>
> ---
> drivers/video/backlight/adp8870_bl.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
> index 8d50e0299578..79901fb4fcd1 100644
> --- a/drivers/video/backlight/adp8870_bl.c
> +++ b/drivers/video/backlight/adp8870_bl.c
> @@ -811,9 +811,14 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,
> if (!ret) {
> reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8870_write(data->client, ADP8870_CFGR, reg_val);
> - }
> - mutex_unlock(&data->lock);
> + ret = adp8870_write(data->client,
> + ADP8870_CFGR, reg_val);
> + if (ret) {
> + mutex_unlock(&data->lock);
> + return ret;
> + }
> + } else
> + mutex_unlock(&data->lock);

Please don't unbalance the lock paths. Instead check the value of ret *after*
the existing mutex unlock (which will also means that the failed
adp8870_read() isn't silently ignored).

Also there's not much point in fixing this site without also fixing the
missing return checks on adp8870_set_bits() and adp8870_clr_bits() in
the same function.


Daniel.


> }
>
> return count;
> --
> 2.17.2 (Apple Git-113)
>