[dpdk-dev] [PATCH] service: fix shifts to operate on 64 bit integers

Van Haaren, Harry harry.van.haaren at intel.com
Mon Jul 31 18:20:31 CEST 2017


> From: Gaëtan Rivet [mailto:gaetan.rivet at 6wind.com]
> Sent: Monday, July 31, 2017 5:18 PM
> To: Van Haaren, Harry <harry.van.haaren at intel.com>
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] service: fix shifts to operate on 64 bit integers
> 
> Hi Harry,
> 
> On Mon, Jul 31, 2017 at 04:58:27PM +0100, Harry van Haaren wrote:
> > This commit fixes shifts to an integer (1 << shift) which
> > is assumed to be a 32-bit integer. In this case, the shift is
> > variable and expected to be valid for 64-bit integers. Given that
> > the expectation to work with 64 bits exists, we must ensure that
> > the (1 << shift) one in that formula is actually a uin64_t.
> >
> > Simply defining a const uint64_t and using it ensures the compiler
> > is aware of the intention. The issue would only manifest if there
> > were greater than 31 services registered.
> >
> > Fixes: 21698354c832 ("service: introduce service cores concept")
> >
> > Signed-off-by: Harry van Haaren <harry.van.haaren at intel.com>
> > ---
> >  lib/librte_eal/common/rte_service.c | 16 ++++++++++------
> >  1 file changed, 10 insertions(+), 6 deletions(-)
> >
> > diff --git a/lib/librte_eal/common/rte_service.c b/lib/librte_eal/common/rte_service.c
> > index e82b9ad..8c1cffa 100644
> > --- a/lib/librte_eal/common/rte_service.c
> > +++ b/lib/librte_eal/common/rte_service.c
> > @@ -285,8 +285,9 @@ rte_service_unregister(struct rte_service_spec *spec)
> >
> >  	s->internal_flags &= ~(SERVICE_F_REGISTERED);
> >
> > +	const uint64_t one = 1;
> >  	for (i = 0; i < RTE_MAX_LCORE; i++)
> > -		lcore_states[i].service_mask &= ~(1 << service_id);
> > +		lcore_states[i].service_mask &= ~(one << service_id);
> 
> Why not use UINT64_C(1)?

Mostly because I've never heard of it before :) Thanks for review, still learnin' every day! Sending v2's every other day...


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