From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Date: Fri, 24 Feb 2012 19:10:50 +0000 Subject: Re: [PATCH 2/2] enic: Silence Sparse Warning: "dubious: x | !y" Message-Id: <1330110650.2397.8.camel@bwh-desktop> List-Id: References: <1330102654-2474-1-git-send-email-santoshprasadnayak@gmail.com> In-Reply-To: <1330102654-2474-1-git-send-email-santoshprasadnayak@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: santosh nayak Cc: benve@cisco.com, roprabhu@cisco.com, neepatel@cisco.com, nistrive@cisco.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org On Fri, 2012-02-24 at 22:27 +0530, santosh nayak wrote: > From: Santosh Nayak > > Sparse is giving the following warning: > "warning: dubious: x | !y" > > "enic_are_pp_different" is static and expected to return true or false. > Logical or is indended here. With logical or, in best case, execution will be > faster because if leftmost operand is true then no need to check other operands. The shortcut behaviour of logical-or means more conditional jumps to be predicted and more potential for pipeline stalls. So bitwise-or can in some cases be more efficient. But this function appears to be control-path code where micro-optimisation just doesn't matter. Use of logical-or can be justified purely on the grounds of clarity. Ben. > Signed-off-by: Santosh Nayak > --- > drivers/net/ethernet/cisco/enic/enic_pp.c | 8 ++++---- > 1 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/ethernet/cisco/enic/enic_pp.c b/drivers/net/ethernet/cisco/enic/enic_pp.c > index dafea1e..3a6de22 100644 > --- a/drivers/net/ethernet/cisco/enic/enic_pp.c > +++ b/drivers/net/ethernet/cisco/enic/enic_pp.c > @@ -159,10 +159,10 @@ static int enic_unset_port_profile(struct enic *enic, int vf) > static int enic_are_pp_different(struct enic_port_profile *pp1, > struct enic_port_profile *pp2) > { > - return strcmp(pp1->name, pp2->name) | !!memcmp(pp1->instance_uuid, > - pp2->instance_uuid, PORT_UUID_MAX) | > - !!memcmp(pp1->host_uuid, pp2->host_uuid, PORT_UUID_MAX) | > - !!memcmp(pp1->mac_addr, pp2->mac_addr, ETH_ALEN); > + return strcmp(pp1->name, pp2->name) || !!memcmp(pp1->instance_uuid, > + pp2->instance_uuid, PORT_UUID_MAX) || > + !!memcmp(pp1->host_uuid, pp2->host_uuid, PORT_UUID_MAX) || > + !!memcmp(pp1->mac_addr, pp2->mac_addr, ETH_ALEN); > } > > static int enic_pp_preassociate(struct enic *enic, int vf, -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.