Re: [PATCH net] net: ethernet: adi: adin1110: Fix some error handling path in adin1110_read_fifo()

[Christophe JAILLET]

Le 04/10/2024 à 13:47, Dan Carpenter a écrit :
> On Thu, Oct 03, 2024 at 08:53:15PM +0200, Christophe JAILLET wrote:
> > If 'frame_size' is too small or if 'round_len' is an error code, it is
> > likely that an error code should be returned to the caller.
> >
> > Actually, 'ret' is likely to be 0, so if one of these sanity checks fails,
> > 'success' is returned.
> >
> > Return -EINVAL instead.
> >
> > Fixes: bc93e19d088b ("net: ethernet: adi: Add ADIN1110 support")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > This patch is speculative.
> > If returning 0 is what was intended, then an explicit 0 would be better.
>
> I have an unpublished Smatch warning for these:
>
> drivers/net/ethernet/adi/adin1110.c:321 adin1110_read_fifo() info: returning a literal zero is cleaner
> drivers/net/ethernet/adi/adin1110.c:325 adin1110_read_fifo() info: returning a literal zero is cleaner
>
> It's a pity that deliberately doing a "return ret;" when ret is zero is so
> common.  Someone explained to me that it was "done deliberately to express that
> we were propagating the success from frob_whatever()".  No no no!
>
> I don't review these warnings unless I'm fixing a bug in the driver because
> they're too common.  The only ones I review are:
>
> 	ret = frob();
> 	if (!ret)
> 		return ret;
>
> Maybe 20% of the time those warnings indicate a reversed if statement.
>
> Your heuristic here is very clever and I'll try steal it to create a new more
> specific warning.

Well my heuristic is mostly luck, here ;-)

Anyway, what I was looking for (un-initialized last argument in some 
function) could be nice to have in smatch, if not already present.


Finally, if you want, I can give a look at the warnings if you share the 
log.

CJ

> regards,
> dan carpenter