netdev - Re: [PATCH][next] bpf: remove redundant assignment to err

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Message-ID: <20190603104930.466a306b@cakuba.netronome.com>
Date:   Mon, 3 Jun 2019 10:49:30 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Colin Ian King <colin.king@...onical.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Björn Töpel <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        netdev@...r.kernel.org, xdp-newbies@...r.kernel.org,
        bpf@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] bpf: remove redundant assignment to err

On Mon, 3 Jun 2019 18:39:16 +0100, Colin Ian King wrote:
> On 03/06/2019 18:21, Jakub Kicinski wrote:
> > On Mon,  3 Jun 2019 18:02:47 +0100, Colin King wrote:  
> >> From: Colin Ian King <colin.king@...onical.com>
> >>
> >> The variable err is assigned with the value -EINVAL that is never
> >> read and it is re-assigned a new value later on.  The assignment is
> >> redundant and can be removed.
> >>
> >> Addresses-Coverity: ("Unused value")
> >> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> >> ---
> >>  kernel/bpf/devmap.c | 2 +-
> >>  kernel/bpf/xskmap.c | 2 +-
> >>  2 files changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> >> index 5ae7cce5ef16..a76cc6412fc4 100644
> >> --- a/kernel/bpf/devmap.c
> >> +++ b/kernel/bpf/devmap.c
> >> @@ -88,7 +88,7 @@ static u64 dev_map_bitmap_size(const union bpf_attr *attr)
> >>  static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
> >>  {
> >>  	struct bpf_dtab *dtab;
> >> -	int err = -EINVAL;
> >> +	int err;
> >>  	u64 cost;  
> > 
> > Perhaps keep the variables ordered longest to shortest?  
> 
> Is that a required coding standard?

For networking code, yes.  Just look around the files you're changing
and see for yourself.

> >>  	if (!capable(CAP_NET_ADMIN))
> >> diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c
> >> index 22066c28ba61..26859c6c9491 100644
> >> --- a/kernel/bpf/xskmap.c
> >> +++ b/kernel/bpf/xskmap.c
> >> @@ -17,7 +17,7 @@ struct xsk_map {
> >>  
> >>  static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
> >>  {
> >> -	int cpu, err = -EINVAL;
> >> +	int cpu, err;
> >>  	struct xsk_map *m;
> >>  	u64 cost;  
> > 
> > And here.