Re: [PATCH net-next] tcp: tcp_sendmsg() wrong access to sk_route_caps

[Joe Perches <joe@perches.com>]

On Mon, 2011-11-28 at 17:04 +0100, Eric Dumazet wrote:
> Le lundi 28 novembre 2011 à 02:46 -0800, Joe Perches a écrit :
> > On Mon, 2011-11-28 at 11:27 +0100, Eric Dumazet wrote:
> > > +	sg = !!(sk->sk_route_caps & NETIF_F_SG);
> > As sg is now bool, using !! is unnecessary.
> > A commit was done recently to remove one.
> > 3ad9b358e03fd9dbf6705721490c811b666b0fe2
> Hmm... I find it dangerous and error prone. Obviously not at the time we
> commit such changes, but later, because a future reader might be fooled.
> Using !!(expr) is pretty clear about the potential problem, and
> generates no extra code if a bool is used for the target.

Though I don't think
	bool = expr;
is particularly error prone,
spatch shows 58 uses of
	bool = !!expr;
in net-next drivers/net.

It might be useful to standardize on either the
implicit or explicit !! style.

I think !! is an intentional and sensible style
and should be the preferred use.

Perhaps a checkpatch warning should be issued
when the implicit cast is used.