From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [PATCH v2] net/core: Fix BUG to BUG_ON conditionals. Date: Mon, 9 Oct 2017 16:06:20 -0700 Message-ID: <20171009230618.e5gla2iuqwmndkig@ast-mbp> References: <20171009153759.km3lqss7hb72wrze@debian> <20171009171540.lgmk2slq3bdrptxk@ast-mbp.dhcp.thefacebook.com> <20171009202633.ep5pbi2tlg7dqidz@sasha-lappy> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Tim Hansen , "davem@davemloft.net" , "willemb@google.com" , "edumazet@google.com" , "soheil@google.com" , "pabeni@redhat.com" , "elena.reshetova@intel.com" , "tom@quantonium.net" , "Jason@zx2c4.com" , "fw@strlen.de" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: "Levin, Alexander (Sasha Levin)" Return-path: Content-Disposition: inline In-Reply-To: <20171009202633.ep5pbi2tlg7dqidz@sasha-lappy> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, Oct 09, 2017 at 08:26:34PM +0000, Levin, Alexander (Sasha Levin) wrote: > On Mon, Oct 09, 2017 at 10:15:42AM -0700, Alexei Starovoitov wrote: > >On Mon, Oct 09, 2017 at 11:37:59AM -0400, Tim Hansen wrote: > >> Fix BUG() calls to use BUG_ON(conditional) macros. > >> > >> This was found using make coccicheck M=net/core on linux next > >> tag next-2017092 > >> > >> Signed-off-by: Tim Hansen > >> --- > >> net/core/skbuff.c | 15 ++++++--------- > >> 1 file changed, 6 insertions(+), 9 deletions(-) > >> > >> diff --git a/net/core/skbuff.c b/net/core/skbuff.c > >> index d98c2e3ce2bf..34ce4c1a0f3c 100644 > >> --- a/net/core/skbuff.c > >> +++ b/net/core/skbuff.c > >> @@ -1350,8 +1350,7 @@ struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask) > >> /* Set the tail pointer and length */ > >> skb_put(n, skb->len); > >> > >> - if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len)) > >> - BUG(); > >> + BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len)); > > > >I'm concerned with this change. > >1. Calling non-trivial bit of code inside the macro is a poor coding style (imo) > >2. BUG_ON != BUG. Some archs like mips and ppc have HAVE_ARCH_BUG_ON and implementation > >of BUG and BUG_ON look quite different. > > For these archs, wouldn't it then be more efficient to use BUG_ON rather than BUG()? why more efficient? any data to prove that? I'm pointing that the change is not equivalent and this code has been around forever (pre-git days), so I see no reason to risk changing it.