[dpdk-dev] reply: [PATCH] hash: fix possible uninitialized variable

[dpdk-dev] reply: [PATCH] hash: fix possible uninitialized variable

[haiyangtan(谭海洋)]

> -----Original Message-----
> From:  Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> 发送时间: 2018年12月24日 18:30
> 收件人: Stephen Hemminger <stephen@networkplumber.org>;
> haiyangtan <haiyangtan@tencent.com>
> Cc:  dev@dpdk.org
> Subject: RE: [dpdk-dev] [PATCH] hash: fix possible uninitialized variable(Internet
> mail)
> 
> 
> 
> > -----Original Message-----
> > From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> > Sent: Sunday, December 23, 2018 7:44 AM
> > To: Haiyang Tan <haiyangtan@tencent.com>
> > Cc: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>; dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH] hash: fix possible uninitialized variable
> >
> > On Sat, 22 Dec 2018 04:10:59 -0800
> > Haiyang Tan <haiyangtan@tencent.com> wrote:
> >
> > > The uninitialized field 'extra_flag' of hash_cuckoo_params may enable
> > > certain feature silently. Typically, if bit0 of 'extra_flag' set, the
> > > hardware transactional memory support will be enabled unexpectedly.
> > >
> > > Signed-off-by: Haiyang Tan <haiyangtan@tencent.com>
> >
> > This is not necessary. Structure initializations will fill in the other
> > elements with zero.
> >
> > https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Designated-Inits.html
> >   Omitted field members are implicitly initialized the same as objects that
> > have static storage duration.
> 
> Agree with Stephen, this is part of the C language.
> 
> Haiyang, are you experiencing a real issue in your app or is your proposal
> triggered purely by code review?
> 
> Haiyang, it seems that the extra_flags was recently added in librte_hash, but
> left behind in librte_table. For better readability, I suggest you send a quick
> patch that explicitly initializes the extra_flag with 0, what do you think?
> 
> 	struct rte_hash_parameters hash_cuckoo_params = {
> 		...
> 		.extra_flag = 0,
> 	};
> 
> Regards,
> Cristian
> 

Hi Stephen and Cristian,  I have checked C99 standard and get the same conclusion which mentioned in stephen's email,

So this patch is unnecessary and please ignore it.

BR!

Haiyang