Re: [dpdk-dev] [dpdk-stable] [PATCH] app/testpmd: fix uninitialized members of mpls

[Ori Kam <orika@mellanox.com>]

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Monday, February 3, 2020 7:46 PM
> To: Ori Kam <orika@mellanox.com>; Wenzhuo Lu <wenzhuo.lu@intel.com>;
> Jingjing Wu <jingjing.wu@intel.com>; Bernard Iremonger
> <bernard.iremonger@intel.com>
> Cc: dev@dpdk.org; Slava Ovsiienko <viacheslavo@mellanox.com>;
> stable@dpdk.org
> Subject: Re: [dpdk-stable] [PATCH] app/testpmd: fix uninitialized members of
> mpls
> 
> On 2/3/2020 10:21 AM, Ferruh Yigit wrote:
> > On 2/2/2020 8:23 AM, Ori Kam wrote:
> >> Hi Ferruh,
> >>
> >> PSB,
> >> Thanks,
> >> Ori
> >>
> >>> -----Original Message-----
> >>> From: Ferruh Yigit <ferruh.yigit@intel.com>
> >>> Sent: Friday, January 31, 2020 1:08 PM
> >>> To: Ori Kam <orika@mellanox.com>; Wenzhuo Lu
> <wenzhuo.lu@intel.com>;
> >>> Jingjing Wu <jingjing.wu@intel.com>; Bernard Iremonger
> >>> <bernard.iremonger@intel.com>
> >>> Cc: dev@dpdk.org; Slava Ovsiienko <viacheslavo@mellanox.com>;
> >>> stable@dpdk.org
> >>> Subject: Re: [PATCH] app/testpmd: fix uninitialized members of mpls
> >>>
> >>> On 1/30/2020 4:59 PM, Ori Kam wrote:
> >>>> Some of the memebers of the mpls struct are not initialized.
> >>>> this commit init the uninitialized members.
> >>>>
> >>>> Coverity issue: 325735
> >>>> Fixes: 3e77031be855 ("app/testpmd: add MPLSoGRE encapsulation")
> >>>> Cc: stable@dpdk.org
> >>>>
> >>>> Signed-off-by: Ori Kam <orika@mellanox.com>
> >>>> ---
> >>>>  app/test-pmd/cmdline_flow.c | 4 +++-
> >>>>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/app/test-pmd/cmdline_flow.c b/app/test-pmd/cmdline_flow.c
> >>>> index e99e24c..c2cc4c5 100644
> >>>> --- a/app/test-pmd/cmdline_flow.c
> >>>> +++ b/app/test-pmd/cmdline_flow.c
> >>>> @@ -4576,7 +4576,9 @@ static int comp_set_raw_index(struct context *,
> >>> const struct token *,
> >>>>  	struct rte_flow_item_gre gre = {
> >>>>  		.protocol = rte_cpu_to_be_16(ETHER_TYPE_MPLS_UNICAST),
> >>>>  	};
> >>>> -	struct rte_flow_item_mpls mpls;
> >>>> +	struct rte_flow_item_mpls mpls = {
> >>>> +		.ttl = 0,
> >>>> +	};
> >>>
> >>> why not use "= {0};", the end result will be same, struct will be all zeroed
> out
> >>> in both case, "= {0};" makes the intention more obvious I think.
> >>>
> >>
> >> On some compilers this kind of  initialization result in an error:
> >> error: missing braces around initializer
> >
> > As far as I remember, that is triggered with old compiler, when you are
> > initializing array of structs, or first element of the struct is an array (which
> > is the case for mpls struct), in that case ={{0}} was solving the issue.
> >
> > Anyway, I got the concern, the patch looks good to me.
> 
> Also seems "={}" is working in that case, thanks to Stephen, it is cleaner than
> "={{0}}", what do you think about using "={}" ?
> 
Thanks for the idea, but it still causes issue,
"error: missing initializer for field 'label_tc_s' of 'struct rte_flow_item_mpls' [-Werror=missing-field-initializers]
 struct rte_flow_item_mpls mpls = {};"
Just for reference  I'm using gcc 4.8.5 (Red Hat 4.8.5-4)
I know it is very old, but some of our customers are using it.
So if you don't mind I will keep my code as is.

> >
> >> it looks like a known issue of GCC
> >> So I just prefer to init the relevant fields.
> >>
> >>>>  	uint8_t *header;
> >>>>  	int ret;
> >>>>
> >>>>
> >>
> >