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[v2,19/26] media: ov9650: fix bogus warnings

Message ID a4092bf193d3a1c9ccd0dae4a735a1cbf5261ecd.1509569763.git.mchehab@s-opensource.com (mailing list archive)
State New, archived
Headers show

Commit Message

Mauro Carvalho Chehab Nov. 1, 2017, 9:05 p.m. UTC 
The smatch logic gets confused with the syntax used to check if the
ov9650x_read() reads succedded:
	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg2'.
	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg1'.

There's nothing wrong with the original logic, except that
it is a little more harder to review.

So, let's stick with the syntax that won't cause read
issues.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
 drivers/media/i2c/ov9650.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Comments

Nicholas Mc Guire Nov. 2, 2017, 10:06 a.m. UTC | #1 
On Wed, Nov 01, 2017 at 05:05:56PM -0400, Mauro Carvalho Chehab wrote:
> The smatch logic gets confused with the syntax used to check if the
> ov9650x_read() reads succedded:
> 	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg2'.
> 	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg1'.
> 
> There's nothing wrong with the original logic, except that
> it is a little more harder to review.

Maybe I do not understand the original logic correctly but
ov965x_read(...) is passing on the return value from 
i2c_transfer() -> __i2c_transfer() and thus if one of those
calls would have been a negativ error status it would have simply
executed the next call to ov965x_read() and if that 
call would have suceeded it would eventually reach the
line " exposure = ((reg2 & 0x3f) << 10) | (reg1 << 2) |..."
with the potential to operate on uninitialized registers reg0/1/2
the current code sems only to handle error conditions in the last
call to ov965x_read() correctly.

I think this is actually not an equivalent transform but a bug-fix
of  case V4L2_CID_EXPOSURE_AUTO: (aside from being a code inconsistency)
So should this not carry a 
 Fixes: 84a15ded76ec ("[media] V4L: Add driver for OV9650/52 image sensors")
tag ?

thx!
hofrat

> 
> So, let's stick with the syntax that won't cause read
> issues.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Reviewed-by: Nicholas Mc Guire <hofrat@osadl.org>

> ---
>  drivers/media/i2c/ov9650.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov9650.c b/drivers/media/i2c/ov9650.c
> index 69433e1e2533..e519f278d5f9 100644
> --- a/drivers/media/i2c/ov9650.c
> +++ b/drivers/media/i2c/ov9650.c
> @@ -886,10 +886,12 @@ static int __g_volatile_ctrl(struct ov965x *ov965x, struct v4l2_ctrl *ctrl)
>  		if (ctrl->val == V4L2_EXPOSURE_MANUAL)
>  			return 0;
>  		ret = ov965x_read(client, REG_COM1, &reg0);
> -		if (!ret)
> -			ret = ov965x_read(client, REG_AECH, &reg1);
> -		if (!ret)
> -			ret = ov965x_read(client, REG_AECHM, &reg2);
> +		if (ret < 0)
> +			return ret;
> +		ret = ov965x_read(client, REG_AECH, &reg1);
> +		if (ret < 0)
> +			return ret;
> +		ret = ov965x_read(client, REG_AECHM, &reg2);
>  		if (ret < 0)
>  			return ret;
>  		exposure = ((reg2 & 0x3f) << 10) | (reg1 << 2) |
> -- 
> 2.13.6
>
Nicholas Mc Guire Nov. 2, 2017, 10:22 a.m. UTC | #2 
On Thu, Nov 02, 2017 at 10:06:06AM +0000, Nicholas Mc Guire wrote:
> On Wed, Nov 01, 2017 at 05:05:56PM -0400, Mauro Carvalho Chehab wrote:
> > The smatch logic gets confused with the syntax used to check if the
> > ov9650x_read() reads succedded:
> > 	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg2'.
> > 	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg1'.
> > 
> > There's nothing wrong with the original logic, except that
> > it is a little more harder to review.
> 
> Maybe I do not understand the original logic correctly but
> ov965x_read(...) is passing on the return value from 
> i2c_transfer() -> __i2c_transfer() and thus if one of those
> calls would have been a negativ error status it would have simply
> executed the next call to ov965x_read() and if that 
> call would have suceeded it would eventually reach the
> line " exposure = ((reg2 & 0x3f) << 10) | (reg1 << 2) |..."
> with the potential to operate on uninitialized registers reg0/1/2
> the current code sems only to handle error conditions in the last
> call to ov965x_read() correctly.

sorry - sent that out too fast - the logic is equivalent the negative
returns are treated correctly because only the success case is 
being returned explicidly as 0 in ov965x_read() return statement
by checking for the expecte return of 1 from i2c_transfer() wrapping
it to 0.

sorry for the noise.

thx!
hofrat

> 
> I think this is actually not an equivalent transform but a bug-fix
> of  case V4L2_CID_EXPOSURE_AUTO: (aside from being a code inconsistency)
> So should this not carry a 
>  Fixes: 84a15ded76ec ("[media] V4L: Add driver for OV9650/52 image sensors")
> tag ?
> 
> thx!
> hofrat
> 
> > 
> > So, let's stick with the syntax that won't cause read
> > issues.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
> 
> Reviewed-by: Nicholas Mc Guire <hofrat@osadl.org>
> 
> > ---
> >  drivers/media/i2c/ov9650.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/ov9650.c b/drivers/media/i2c/ov9650.c
> > index 69433e1e2533..e519f278d5f9 100644
> > --- a/drivers/media/i2c/ov9650.c
> > +++ b/drivers/media/i2c/ov9650.c
> > @@ -886,10 +886,12 @@ static int __g_volatile_ctrl(struct ov965x *ov965x, struct v4l2_ctrl *ctrl)
> >  		if (ctrl->val == V4L2_EXPOSURE_MANUAL)
> >  			return 0;
> >  		ret = ov965x_read(client, REG_COM1, &reg0);
> > -		if (!ret)
> > -			ret = ov965x_read(client, REG_AECH, &reg1);
> > -		if (!ret)
> > -			ret = ov965x_read(client, REG_AECHM, &reg2);
> > +		if (ret < 0)
> > +			return ret;
> > +		ret = ov965x_read(client, REG_AECH, &reg1);
> > +		if (ret < 0)
> > +			return ret;
> > +		ret = ov965x_read(client, REG_AECHM, &reg2);
> >  		if (ret < 0)
> >  			return ret;
> >  		exposure = ((reg2 & 0x3f) << 10) | (reg1 << 2) |
> > -- 
> > 2.13.6
> >
diff mbox

Patch

diff --git a/drivers/media/i2c/ov9650.c b/drivers/media/i2c/ov9650.c
index 69433e1e2533..e519f278d5f9 100644
--- a/drivers/media/i2c/ov9650.c
+++ b/drivers/media/i2c/ov9650.c
@@ -886,10 +886,12 @@  static int __g_volatile_ctrl(struct ov965x *ov965x, struct v4l2_ctrl *ctrl)
 		if (ctrl->val == V4L2_EXPOSURE_MANUAL)
 			return 0;
 		ret = ov965x_read(client, REG_COM1, &reg0);
-		if (!ret)
-			ret = ov965x_read(client, REG_AECH, &reg1);
-		if (!ret)
-			ret = ov965x_read(client, REG_AECHM, &reg2);
+		if (ret < 0)
+			return ret;
+		ret = ov965x_read(client, REG_AECH, &reg1);
+		if (ret < 0)
+			return ret;
+		ret = ov965x_read(client, REG_AECHM, &reg2);
 		if (ret < 0)
 			return ret;
 		exposure = ((reg2 & 0x3f) << 10) | (reg1 << 2) |