On Thu, Jun 13, 2024 at 11:48 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> On Wed, Jun 12, 2024 at 06:05:54PM +0000, Joy Chakraborty wrote:
> > Read callbacks registered with nvmem core expect 0 to be returned on
> > success and a negative value to be returned on failure.
> >
> > abx80x_nvmem_xfer() on read calls i2c_smbus_read_i2c_block_data() which
> > returns the number of bytes read on success as per its api description,
> > this return value is handled as an error and returned to nvmem even on
> > success.
> >
> > Fix to handle all possible values that would be returned by
> > i2c_smbus_read_i2c_block_data().
> >
> > Fixes: e90ff8ede777 ("rtc: abx80x: Add nvmem support")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Joy Chakraborty <joychakr@xxxxxxxxxx>
> > ---
> > drivers/rtc/rtc-abx80x.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
> > index fde2b8054c2e..0f5847d1ca2a 100644
> > --- a/drivers/rtc/rtc-abx80x.c
> > +++ b/drivers/rtc/rtc-abx80x.c
> > @@ -711,9 +711,16 @@ static int abx80x_nvmem_xfer(struct abx80x_priv *priv, unsigned int offset,
> > else
> > ret = i2c_smbus_read_i2c_block_data(priv->client, reg,
> > len, val);
> > - if (ret)
> > + if (ret < 0)
> > return ret;
> >
> > + if (!write) {
> > + if (ret)
> > + len = ret;
> > + else
> > + return -EIO;
> > + }
>
> I guess this is the conservative approach. Ie. Don't break things
> which aren't already broken. But I suspect the correct approach is to
> say:
>
> if (ret != len)
> return -EIO;
>
> Ah well. Being conservative is good. It probably doesn't ever happen
> in real life so it probably doesn't matter either way.
>
> I don't really like the if (write) follow by and if (!write)... It
> would add more lines, but improve readability if we just duplicate the
> code a big:
>
> if (write) {
> ret = write();
> if (ret)
> return ret;
> } else {
> ret = read();
> if (ret <= 0)
> return ret ?: -EIO;
> len = ret;
> }
>
Sure, I'll do this in a follow up patch.
Thanks
Joy
> regards,
> dan carpenter
>
