[patch -resend] [media] az6007: precedence bug in az6007_i2c_xfer()

[patch -resend] [media] az6007: precedence bug in az6007_i2c_xfer()

[Dan Carpenter]

The intent here was to test that the flag was clear but the '!' has
higher precedence than the '&'.  I2C_M_RD is 0x1 so the current code is
equivalent to "&& (!sgs[i].flags) ..."

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
I sent this originally on Wed, 25 Jan 2012 and Emil Goode sent the same
fix on Thu, May 3, 2012.

diff --git a/drivers/media/dvb/dvb-usb/az6007.c b/drivers/media/dvb/dvb-usb/az6007.c
index 4008b9c..f6f0cf9 100644
--- a/drivers/media/dvb/dvb-usb/az6007.c
+++ b/drivers/media/dvb/dvb-usb/az6007.c
@@ -711,7 +711,7 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 		addr = msgs[i].addr << 1;
 		if (((i + 1) < num)
 		    && (msgs[i].len == 1)
-		    && (!msgs[i].flags & I2C_M_RD)
+		    && (!(msgs[i].flags & I2C_M_RD))
 		    && (msgs[i + 1].flags & I2C_M_RD)
 		    && (msgs[i].addr == msgs[i + 1].addr)) {
 			/*

Re: [patch -resend] [media] az6007: precedence bug in az6007_i2c_xfer()

[Mauro Carvalho Chehab]

Em 27-06-2012 06:06, Dan Carpenter escreveu:
> The intent here was to test that the flag was clear but the '!' has
> higher precedence than the '&'.  I2C_M_RD is 0x1 so the current code is
> equivalent to "&& (!sgs[i].flags) ..."
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> I sent this originally on Wed, 25 Jan 2012 and Emil Goode sent the same
> fix on Thu, May 3, 2012.
> 
> diff --git a/drivers/media/dvb/dvb-usb/az6007.c b/drivers/media/dvb/dvb-usb/az6007.c
> index 4008b9c..f6f0cf9 100644
> --- a/drivers/media/dvb/dvb-usb/az6007.c
> +++ b/drivers/media/dvb/dvb-usb/az6007.c
> @@ -711,7 +711,7 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
>   		addr = msgs[i].addr << 1;
>   		if (((i + 1) < num)
>   		    && (msgs[i].len == 1)
> -		    && (!msgs[i].flags & I2C_M_RD)
> +		    && (!(msgs[i].flags & I2C_M_RD))
>   		    && (msgs[i + 1].flags & I2C_M_RD)
>   		    && (msgs[i].addr == msgs[i + 1].addr)) {
>   			/*
> 

Dan,

Your logic is correct, however, I didn't apply this patch because it broke
the driver.

I'll need to re-visit the driver when I have some time, in order to be
able to apply this one, without breaking the driver. I'll likely need to
change some other things on this routine.

(this has a low priority, as the driver is working properly the way it is).

So, I'm keeping your patch at patchwork, while I don't find some time for it.

Regards,
Mauro

Re: [patch -resend] [media] az6007: precedence bug in az6007_i2c_xfer()

[Dan Carpenter]

On Wed, Jun 27, 2012 at 10:11:00AM -0300, Mauro Carvalho Chehab wrote:
> Em 27-06-2012 06:06, Dan Carpenter escreveu:
> > The intent here was to test that the flag was clear but the '!' has
> > higher precedence than the '&'.  I2C_M_RD is 0x1 so the current code is
> > equivalent to "&& (!sgs[i].flags) ..."
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > I sent this originally on Wed, 25 Jan 2012 and Emil Goode sent the same
> > fix on Thu, May 3, 2012.
> > 
> > diff --git a/drivers/media/dvb/dvb-usb/az6007.c b/drivers/media/dvb/dvb-usb/az6007.c
> > index 4008b9c..f6f0cf9 100644
> > --- a/drivers/media/dvb/dvb-usb/az6007.c
> > +++ b/drivers/media/dvb/dvb-usb/az6007.c
> > @@ -711,7 +711,7 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
> >   		addr = msgs[i].addr << 1;
> >   		if (((i + 1) < num)
> >   		    && (msgs[i].len == 1)
> > -		    && (!msgs[i].flags & I2C_M_RD)
> > +		    && (!(msgs[i].flags & I2C_M_RD))
> >   		    && (msgs[i + 1].flags & I2C_M_RD)
> >   		    && (msgs[i].addr == msgs[i + 1].addr)) {
> >   			/*
> > 
> 
> Dan,
> 
> Your logic is correct, however, I didn't apply this patch because it broke
> the driver.
> 
> I'll need to re-visit the driver when I have some time, in order to be
> able to apply this one, without breaking the driver. I'll likely need to
> change some other things on this routine.
> 
> (this has a low priority, as the driver is working properly the way it is).
> 
> So, I'm keeping your patch at patchwork, while I don't find some time for it.

We could just put a comment next to the code and forget about it.

               && (!(msgs[i].flags & I2C_M_RD)) /* the fix needs testing. */

Sparse complains about this so it people are going to keep sending
patches for it.  It's not like you should be stuck doing all the
work.

regards,
dan carpenter