* [PATCH] media: ov7670: check status of ov7670_read
@ 2020-08-28 14:55 trix
2020-08-28 15:13 ` Nick Desaulniers
2020-10-06 12:41 ` Sakari Ailus
0 siblings, 2 replies; 5+ messages in thread
From: trix @ 2020-08-28 14:55 UTC (permalink / raw)
To: corbet, mchehab, natechancellor, ndesaulniers
Cc: linux-media, linux-kernel, Tom Rix
From: Tom Rix <trix@redhat.com>
clang static analysis flags this representative problem
drivers/media/i2c/ov7670.c:1463:9: warning: Assigned
value is garbage or undefined
*value = gain;
^ ~~~~
gain is set by a successful call to ov7670_read()
So check that ov7670_read() is successful.
The remaining static analysis problems are false positives.
There appears to be a limitation with checking the
aggregated returns.
Signed-off-by: Tom Rix <trix@redhat.com>
---
drivers/media/i2c/ov7670.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
index b42b289faaef..001d4b09db72 100644
--- a/drivers/media/i2c/ov7670.c
+++ b/drivers/media/i2c/ov7670.c
@@ -929,6 +929,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
ret = ov7670_write(sd, REG_HSTART, (hstart >> 3) & 0xff);
ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
ret += ov7670_read(sd, REG_HREF, &v);
+ if (ret)
+ return ret;
v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
msleep(10);
ret += ov7670_write(sd, REG_HREF, v);
@@ -938,6 +940,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
ret += ov7670_read(sd, REG_VREF, &v);
+ if (ret)
+ return ret;
v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
msleep(10);
ret += ov7670_write(sd, REG_VREF, v);
@@ -1460,6 +1464,8 @@ static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
unsigned char gain;
ret = ov7670_read(sd, REG_GAIN, &gain);
+ if (ret)
+ return ret;
*value = gain;
return ret;
}
@@ -1470,11 +1476,14 @@ static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
unsigned char com8;
ret = ov7670_write(sd, REG_GAIN, value & 0xff);
+ if (ret)
+ return ret;
/* Have to turn off AGC as well */
- if (ret == 0) {
- ret = ov7670_read(sd, REG_COM8, &com8);
- ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
- }
+ ret = ov7670_read(sd, REG_COM8, &com8);
+ if (ret)
+ return ret;
+ ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
+
return ret;
}
--
2.18.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] media: ov7670: check status of ov7670_read
2020-08-28 14:55 [PATCH] media: ov7670: check status of ov7670_read trix
@ 2020-08-28 15:13 ` Nick Desaulniers
2020-08-28 15:36 ` Tom Rix
2020-10-06 12:41 ` Sakari Ailus
1 sibling, 1 reply; 5+ messages in thread
From: Nick Desaulniers @ 2020-08-28 15:13 UTC (permalink / raw)
To: trix
Cc: Jonathan Corbet, Mauro Carvalho Chehab, Nathan Chancellor,
linux-media, LKML, Masahiro Yamada, Nathan Huckleberry
On Fri, Aug 28, 2020 at 7:55 AM <trix@redhat.com> wrote:
>
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis flags this representative problem
>
> drivers/media/i2c/ov7670.c:1463:9: warning: Assigned
> value is garbage or undefined
> *value = gain;
> ^ ~~~~
>
> gain is set by a successful call to ov7670_read()
Indeed, it looks like gain is only valid if the return value from
ov7670_read() is >= 0. Would it be simpler to just initialize gain to
0 in ov7670_g_gain?
Side question; I'm super happy to see someone sending patches for
things identified by clang's static analyzer. I'm curious, Tom, how
did you run it? Did you use the recently landed in kbuild-next
support for the make target `make clang-analyzer`?
>
> So check that ov7670_read() is successful.
>
> The remaining static analysis problems are false positives.
> There appears to be a limitation with checking the
> aggregated returns.
>
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
> drivers/media/i2c/ov7670.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
> index b42b289faaef..001d4b09db72 100644
> --- a/drivers/media/i2c/ov7670.c
> +++ b/drivers/media/i2c/ov7670.c
> @@ -929,6 +929,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
> ret = ov7670_write(sd, REG_HSTART, (hstart >> 3) & 0xff);
> ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
> ret += ov7670_read(sd, REG_HREF, &v);
> + if (ret)
> + return ret;
> v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
> msleep(10);
> ret += ov7670_write(sd, REG_HREF, v);
> @@ -938,6 +940,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
> ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
> ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
> ret += ov7670_read(sd, REG_VREF, &v);
> + if (ret)
> + return ret;
> v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
> msleep(10);
> ret += ov7670_write(sd, REG_VREF, v);
> @@ -1460,6 +1464,8 @@ static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
> unsigned char gain;
>
> ret = ov7670_read(sd, REG_GAIN, &gain);
> + if (ret)
> + return ret;
> *value = gain;
> return ret;
> }
> @@ -1470,11 +1476,14 @@ static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
> unsigned char com8;
>
> ret = ov7670_write(sd, REG_GAIN, value & 0xff);
> + if (ret)
> + return ret;
> /* Have to turn off AGC as well */
> - if (ret == 0) {
> - ret = ov7670_read(sd, REG_COM8, &com8);
> - ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
> - }
> + ret = ov7670_read(sd, REG_COM8, &com8);
> + if (ret)
> + return ret;
> + ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
> +
> return ret;
> }
>
> --
> 2.18.1
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] media: ov7670: check status of ov7670_read
2020-08-28 15:13 ` Nick Desaulniers
@ 2020-08-28 15:36 ` Tom Rix
0 siblings, 0 replies; 5+ messages in thread
From: Tom Rix @ 2020-08-28 15:36 UTC (permalink / raw)
To: Nick Desaulniers
Cc: Jonathan Corbet, Mauro Carvalho Chehab, Nathan Chancellor,
linux-media, LKML, Masahiro Yamada, Nathan Huckleberry
On 8/28/20 8:13 AM, Nick Desaulniers wrote:
> On Fri, Aug 28, 2020 at 7:55 AM <trix@redhat.com> wrote:
>> From: Tom Rix <trix@redhat.com>
>>
>> clang static analysis flags this representative problem
>>
>> drivers/media/i2c/ov7670.c:1463:9: warning: Assigned
>> value is garbage or undefined
>> *value = gain;
>> ^ ~~~~
>>
>> gain is set by a successful call to ov7670_read()
> Indeed, it looks like gain is only valid if the return value from
> ov7670_read() is >= 0. Would it be simpler to just initialize gain to
> 0 in ov7670_g_gain?
It looks like ov7670_read() subroutines both convert > 0 returns to 0.
Setting gain, and similar cases, to 0 means it is ok the setting side effect. maybe it would be ok if this was a void return or there was some known poison value. I did not look into that. There are other routines that are more than a simple get() and i wanted to use the same fix for all of them.
yeah on clang static analysis making it into kbuild! I have been doing these fixes for a couple of months. with a just-built clang, i run 'scan-build make randomconfig', 'scan-build make', then run scan-view on the html. the randomconfig accounts for the very scattered fixes i have posted. generally i would say kernel is doing pretty well, maybe 20 to 1 false to real problems.
Tom
>
> Side question; I'm super happy to see someone sending patches for
> things identified by clang's static analyzer. I'm curious, Tom, how
> did you run it? Did you use the recently landed in kbuild-next
> support for the make target `make clang-analyzer`?
>
>> So check that ov7670_read() is successful.
>>
>> The remaining static analysis problems are false positives.
>> There appears to be a limitation with checking the
>> aggregated returns.
>>
>> Signed-off-by: Tom Rix <trix@redhat.com>
>> ---
>> drivers/media/i2c/ov7670.c | 17 +++++++++++++----
>> 1 file changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
>> index b42b289faaef..001d4b09db72 100644
>> --- a/drivers/media/i2c/ov7670.c
>> +++ b/drivers/media/i2c/ov7670.c
>> @@ -929,6 +929,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
>> ret = ov7670_write(sd, REG_HSTART, (hstart >> 3) & 0xff);
>> ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
>> ret += ov7670_read(sd, REG_HREF, &v);
>> + if (ret)
>> + return ret;
>> v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
>> msleep(10);
>> ret += ov7670_write(sd, REG_HREF, v);
>> @@ -938,6 +940,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
>> ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
>> ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
>> ret += ov7670_read(sd, REG_VREF, &v);
>> + if (ret)
>> + return ret;
>> v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
>> msleep(10);
>> ret += ov7670_write(sd, REG_VREF, v);
>> @@ -1460,6 +1464,8 @@ static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
>> unsigned char gain;
>>
>> ret = ov7670_read(sd, REG_GAIN, &gain);
>> + if (ret)
>> + return ret;
>> *value = gain;
>> return ret;
>> }
>> @@ -1470,11 +1476,14 @@ static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
>> unsigned char com8;
>>
>> ret = ov7670_write(sd, REG_GAIN, value & 0xff);
>> + if (ret)
>> + return ret;
>> /* Have to turn off AGC as well */
>> - if (ret == 0) {
>> - ret = ov7670_read(sd, REG_COM8, &com8);
>> - ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
>> - }
>> + ret = ov7670_read(sd, REG_COM8, &com8);
>> + if (ret)
>> + return ret;
>> + ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
>> +
>> return ret;
>> }
>>
>> --
>> 2.18.1
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] media: ov7670: check status of ov7670_read
2020-08-28 14:55 [PATCH] media: ov7670: check status of ov7670_read trix
2020-08-28 15:13 ` Nick Desaulniers
@ 2020-10-06 12:41 ` Sakari Ailus
2020-10-06 14:17 ` Tom Rix
1 sibling, 1 reply; 5+ messages in thread
From: Sakari Ailus @ 2020-10-06 12:41 UTC (permalink / raw)
To: trix
Cc: corbet, mchehab, natechancellor, ndesaulniers, linux-media, linux-kernel
Hi Tom,
On Fri, Aug 28, 2020 at 07:55:18AM -0700, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis flags this representative problem
>
> drivers/media/i2c/ov7670.c:1463:9: warning: Assigned
> value is garbage or undefined
> *value = gain;
> ^ ~~~~
>
> gain is set by a successful call to ov7670_read()
>
> So check that ov7670_read() is successful.
>
> The remaining static analysis problems are false positives.
> There appears to be a limitation with checking the
> aggregated returns.
>
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
> drivers/media/i2c/ov7670.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
> index b42b289faaef..001d4b09db72 100644
> --- a/drivers/media/i2c/ov7670.c
> +++ b/drivers/media/i2c/ov7670.c
> @@ -929,6 +929,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
> ret = ov7670_write(sd, REG_HSTART, (hstart >> 3) & 0xff);
> ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
> ret += ov7670_read(sd, REG_HREF, &v);
> + if (ret)
> + return ret;
Thanks for the patch.
While the patch fixes a bug, could you also fix adding the return values?
These are valid error codes to begin with, but it makes no sense to add
them together.
> v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
> msleep(10);
> ret += ov7670_write(sd, REG_HREF, v);
> @@ -938,6 +940,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
> ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
> ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
> ret += ov7670_read(sd, REG_VREF, &v);
> + if (ret)
> + return ret;
> v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
> msleep(10);
> ret += ov7670_write(sd, REG_VREF, v);
> @@ -1460,6 +1464,8 @@ static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
> unsigned char gain;
>
> ret = ov7670_read(sd, REG_GAIN, &gain);
> + if (ret)
> + return ret;
> *value = gain;
> return ret;
> }
> @@ -1470,11 +1476,14 @@ static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
> unsigned char com8;
>
> ret = ov7670_write(sd, REG_GAIN, value & 0xff);
> + if (ret)
> + return ret;
> /* Have to turn off AGC as well */
> - if (ret == 0) {
> - ret = ov7670_read(sd, REG_COM8, &com8);
> - ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
> - }
> + ret = ov7670_read(sd, REG_COM8, &com8);
> + if (ret)
> + return ret;
> + ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
> +
> return ret;
> }
>
--
Regards,
Sakari Ailus
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] media: ov7670: check status of ov7670_read
2020-10-06 12:41 ` Sakari Ailus
@ 2020-10-06 14:17 ` Tom Rix
0 siblings, 0 replies; 5+ messages in thread
From: Tom Rix @ 2020-10-06 14:17 UTC (permalink / raw)
To: Sakari Ailus
Cc: corbet, mchehab, natechancellor, ndesaulniers, linux-media, linux-kernel
On 10/6/20 5:41 AM, Sakari Ailus wrote:
> Hi Tom,
>
> On Fri, Aug 28, 2020 at 07:55:18AM -0700, trix@redhat.com wrote:
>> From: Tom Rix <trix@redhat.com>
>>
>> clang static analysis flags this representative problem
>>
>> drivers/media/i2c/ov7670.c:1463:9: warning: Assigned
>> value is garbage or undefined
>> *value = gain;
>> ^ ~~~~
>>
>> gain is set by a successful call to ov7670_read()
>>
>> So check that ov7670_read() is successful.
>>
>> The remaining static analysis problems are false positives.
>> There appears to be a limitation with checking the
>> aggregated returns.
>>
>> Signed-off-by: Tom Rix <trix@redhat.com>
>> ---
>> drivers/media/i2c/ov7670.c | 17 +++++++++++++----
>> 1 file changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
>> index b42b289faaef..001d4b09db72 100644
>> --- a/drivers/media/i2c/ov7670.c
>> +++ b/drivers/media/i2c/ov7670.c
>> @@ -929,6 +929,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
>> ret = ov7670_write(sd, REG_HSTART, (hstart >> 3) & 0xff);
>> ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
>> ret += ov7670_read(sd, REG_HREF, &v);
>> + if (ret)
>> + return ret;
> Thanks for the patch.
>
> While the patch fixes a bug, could you also fix adding the return values?
> These are valid error codes to begin with, but it makes no sense to add
> them together.
Yes. That is a problem, a general problem with this file.
I count 10+
I'll see if fixing the general problem also fixes this problem.
Tom
>
>> v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
>> msleep(10);
>> ret += ov7670_write(sd, REG_HREF, v);
>> @@ -938,6 +940,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
>> ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
>> ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
>> ret += ov7670_read(sd, REG_VREF, &v);
>> + if (ret)
>> + return ret;
>> v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
>> msleep(10);
>> ret += ov7670_write(sd, REG_VREF, v);
>> @@ -1460,6 +1464,8 @@ static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
>> unsigned char gain;
>>
>> ret = ov7670_read(sd, REG_GAIN, &gain);
>> + if (ret)
>> + return ret;
>> *value = gain;
>> return ret;
>> }
>> @@ -1470,11 +1476,14 @@ static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
>> unsigned char com8;
>>
>> ret = ov7670_write(sd, REG_GAIN, value & 0xff);
>> + if (ret)
>> + return ret;
>> /* Have to turn off AGC as well */
>> - if (ret == 0) {
>> - ret = ov7670_read(sd, REG_COM8, &com8);
>> - ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
>> - }
>> + ret = ov7670_read(sd, REG_COM8, &com8);
>> + if (ret)
>> + return ret;
>> + ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
>> +
>> return ret;
>> }
>>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-10-06 14:17 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2020-08-28 14:55 [PATCH] media: ov7670: check status of ov7670_read trix
2020-08-28 15:13 ` Nick Desaulniers
2020-08-28 15:36 ` Tom Rix
2020-10-06 12:41 ` Sakari Ailus
2020-10-06 14:17 ` Tom Rix
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