Re: [dpdk-dev] [PATCH 2/2] examples/ipsec-gw: fix gcc 10 maybe-uninitialized warning

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Kevin,

> gcc 10.0.1 reports:
> 
> ../examples/ipsec-secgw/ipsec_process.c: In function ‘ipsec_process’:
> ../examples/ipsec-secgw/ipsec_process.c:132:34:
> error: ‘grp.m’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>   132 |    grp[n].cnt = pkts + i - grp[n].m;
>       |                            ~~~~~~^~
> 
> Fix by initializing the array.
> 
> Fixes: 3e5f4625dc17 ("examples/ipsec-secgw: make data-path to use IPsec library")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
> ---
> note, commit log violates line length but I didn't want to split warning msg.
> 
> Cc: konstantin.ananyev@intel.com
> Cc: Radu Nicolau <radu.nicolau@intel.com>
> Cc: Akhil Goyal <akhil.goyal@nxp.com>
> ---
>  examples/ipsec-secgw/ipsec_process.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/examples/ipsec-secgw/ipsec_process.c b/examples/ipsec-secgw/ipsec_process.c
> index bb2f2b82d..0032c5c08 100644
> --- a/examples/ipsec-secgw/ipsec_process.c
> +++ b/examples/ipsec-secgw/ipsec_process.c
> @@ -287,5 +287,5 @@ ipsec_process(struct ipsec_ctx *ctx, struct ipsec_traffic *trf)
>  	struct rte_ipsec_group *pg;
>  	struct rte_ipsec_session *ips;
> -	struct rte_ipsec_group grp[RTE_DIM(trf->ipsec.pkts)];
> +	struct rte_ipsec_group grp[RTE_DIM(trf->ipsec.pkts)] = {};

Wouldn't that force to generate an extra instructions to zero-out a chunk of memory,
grp pointitg to?
Considering that this is perf critical pass, that's probably not a best thing.
If disabling compiler warning, is not an option, then probably something like code 
below would help?
Konstantin 

diff --git a/examples/ipsec-secgw/ipsec_process.c b/examples/ipsec-secgw/ipsec_process.c
index bb2f2b82d..6d3a3c9a1 100644
--- a/examples/ipsec-secgw/ipsec_process.c
+++ b/examples/ipsec-secgw/ipsec_process.c
@@ -126,6 +126,7 @@ sa_group(void *sa_ptr[], struct rte_mbuf *pkts[],
        void * const nosa = &spi;

        sa = nosa;
+       grp[0].m = pkts;
        for (i = 0, n = 0; i != num; i++) {

                if (sa != sa_ptr[i]) {