linux-kernel - Re: [PATCH] staging: lustre: ldlm: use designated initializers

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Message-ID: <alpine.LFD.2.20.1612191711550.25173@casper.infradead.org>
Date:   Mon, 19 Dec 2016 17:12:48 +0000 (GMT)
From:   James Simmons <jsimmons@...radead.org>
To:     Bruce Korb <bruce.korb@...il.com>
cc:     Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "John L. Hammond" <john.hammond@...el.com>,
        Emoly Liu <emoly.liu@...el.com>,
        Vitaly Fertman <vitaly_fertman@...atex.com>,
        Bruno Faccini <bruno.faccini@...el.com>,
        Lustre Development List <lustre-devel@...ts.lustre.org>,
        devel@...verdev.osuosl.org
Subject: Re: [PATCH] staging: lustre: ldlm: use designated initializers


> On Mon, Dec 19, 2016 at 8:22 AM, James Simmons
> >> --- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
> >> +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
> >> @@ -143,7 +143,7 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req, __u64 *flags,
> >>       int added = (mode == LCK_NL);
> >>       int overlaps = 0;
> >>       int splitted = 0;
> >> -     const struct ldlm_callback_suite null_cbs = { NULL };
> >> +     const struct ldlm_callback_suite null_cbs = { };
> >>
> >>       CDEBUG(D_DLMTRACE,
> >>              "flags %#llx owner %llu pid %u mode %u start %llu end %llu\n",
> >
> > Nak. Filling null_cbs with random data is a bad idea. If you look at
> > ldlm_lock_create() where this is used you have
> >
> > if (cbs) {
> >         lock->l_blocking_ast = cbs->lcs_blocking;
> >         lock->l_completion_ast = cbs->lcs_completion;
> >         lock->l_glimpse_ast = cbs->lcs_glimpse;
> > }
> >
> > Having lock->l_* point to random addresses is a bad idea.
> > What really needs to be done is proper initialization of that
> > structure. A bunch of patches will be coming to address this.
> 
> I'm not understanding the effect of the original difference.  If you
> specify any initializer, then all fields not specified are filled with
> zero bits. Any pointers are, perforce, NULL.  That should make both "{
> NULL }" and "{}" equivalent.  Maybe a worthwhile change would be to:
> 
>     static const struct ldlm_callback_suite null_cbs;

I perfer this as well.
 
> then it is not even necessary to specify an initializer.