RE: [PATCH] net/nfp: add support of UDP fragmentation offload

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Saturday, 17 February 2024 19.11
> 
> On Sat, 17 Feb 2024 19:02:30 +0100
> Morten Brørup <mb@smartsharesystems.com> wrote:
> 
> > Not formally... it follows the official DPDK Coding Style [1].
> >
> > [1]:
> https://doc.dpdk.org/guides/contributing/coding_style.html#general
> >
> > > Should be:
> > >
> > > 	if ((ol_flags & RTE_MBUF_F_TX_TCP_SEG) == 0 &&
> > > 	    (ol_flags & RTE_MBUF_F_TX_UDP_SEG) == 0)
> > > 		goto clean_txd;
> >
> > This indentation style is mentioned as an alternative in the guide.
> But the example in the guide also uses two tabs for a similar long
> comparison.
> >
> > Personally, I also prefer the style suggested by Stephen, so we might
> want to update the Coding Style. ;-)
> 
> 
> The two tabs is an Intel thing, and I prefer the kernel, line up the
> conditional style.

I prefer 4 space indentation, which is sufficient to notice the indentation. 8 spaces seems overkill to me, and quickly makes the lines too long.
With the editor configured to show tab as 4 spaces, the kernel alignment style ends up with the same indentation for the condition and the code block:

if (a &&
    b)
    ctr++;

Whereas with the "tab as 4 spaces" editor configuration, the double indentation style clearly separates the continued condition from code block:

if (a &&
        b)
    ctr++;

On the other hand, complex conditions are easier readable when aligning logically instead of by a fixed number of tabs, e.g.:

if (a |
    (b &
     (c ^ d)) |
    (e ^ f) |
    g)
    ctr++;

Placing the operators at the beginning also makes the code more readable:

if (a
    | (b
       & (c ^ d))
    | (e ^ f)
    | g)
    ctr++;

I guess that coding styles are mostly a matter of taste.

I wonder if any research into coding styles has reached any conclusions or recommendations, beyond mixing coding styles is bad for readability.

> We really should have a style that can be describe by clang format.
> Other projects like VPP have a target that reformats the code and uses
> one of the clang format templates.

Automated code formatting seems like a good idea.