linux-kernel - Re: [PATCH 7/7] staging:iio:ade7854: Add proper error handling condition

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Date:   Thu, 15 Mar 2018 21:28:00 -0300
From:   Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Barry Song <21cnbao@...il.com>, John Syne <john3909@...il.com>,
        linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
        daniel.baluta@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/7] staging:iio:ade7854: Add proper error handling
 condition

On 03/15, Dan Carpenter wrote:
> On Wed, Mar 14, 2018 at 03:12:18PM -0300, Rodrigo Siqueira wrote:
> > There is some improper error handling for IRQ and device register.  This
> > patch adds a proper verification. The IRQ correction was extracted from
> > John Syne patches.
> > 
> > Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>
> > Signed-off-by: John Syne <john3909@...il.com>
> > ---
> >  drivers/staging/iio/meter/ade7854.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/staging/iio/meter/ade7854.c b/drivers/staging/iio/meter/ade7854.c
> > index 09fd8c067738..49cbe365e43d 100644
> > --- a/drivers/staging/iio/meter/ade7854.c
> > +++ b/drivers/staging/iio/meter/ade7854.c
> > @@ -436,7 +436,7 @@ static int ade7854_initial_setup(struct iio_dev *indio_dev)
> >  
> >  	/* Disable IRQ */
> >  	ret = ade7854_set_irq(dev, false);
> > -	if (ret) {
> > +	if (ret < 0) {
> >  		dev_err(dev, "disable irq failed");
> >  		goto err_ret;
> >  	}
> 
> Why is the original wrong?  It seems fine.

Hi,

If you look at "drivers/staging/iio/meter/ade7854-(i2c|spi).c", you will
find a line like this: " st->write_reg = ade7854_(i2c|spi)_write_reg;".
Than, if you go through the "ade7854_i2c_write_reg" (focus only on i2c
for while) you will see "i2c_master_send(st->i2c, st->tx, count)",
which can returns a positive number that does not necessary means an
error. If you find the same for the spi case, you will end up in the
function "spi_sync_transfer" that only return 0 for success or negative
for failure. So, handling the negative case better fit the i2c and spi case.

Thanks

> regards,
> dan carpenter
> 
>