linux-kernel - Re: [PATCH] srcu: remove never used variable

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Date:   Fri, 23 Feb 2018 09:58:49 +0800
From:   Zhouyi Zhou <zhouzhouyi@...il.com>
To:     Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc:     "josh@...htriplett.org" <josh@...htriplett.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "mathieu.desnoyers@...icios.com" <mathieu.desnoyers@...icios.com>,
        "jiangshanlai@...il.com" <jiangshanlai@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] srcu: remove never used variable

Thanks Paul's encouragement, I will keep studying SRCU code.

On Fri, Feb 23, 2018 at 9:20 AM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
> On Fri, Feb 23, 2018 at 09:04:05AM +0800, Zhouyi Zhou wrote:
>> Thanks Paul for reviewing
>
> And thank you for your interest in SRCU!  I am pretty sure that other
> bugs still remain.  ;-)
>
>                                                         Thanx, Paul
>
>> Cheers
>> Zhouyi
>>
>> On Friday, February 23, 2018, Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
>> wrote:
>>
>> > On Thu, Feb 22, 2018 at 06:52:37AM +0000, zhouzhouyi@...il.com wrote:
>> > > From: Zhouyi Zhou <zhouzhouyi@...il.com>
>> > >
>> > > In function srcu_gp_end, the variable idxnext is never used after assign,
>> > > remove it and its assign statement.
>> > >
>> > > Signed-off-by: Zhouyi Zhou <zhouzhouyi@...il.com>
>> >
>> > Good catch, but Byungchul Park beat you to it.  Please see commit
>> > a72da917f186 ("srcu: Remove dead code in srcu_gp_end()") in -rcu.
>> >
>> >                                                         Thanx, Paul
>> >
>> > > ---
>> > >  kernel/rcu/srcutree.c | 2 --
>> > >  1 file changed, 2 deletions(-)
>> > >
>> > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
>> > > index d5cea81..1241715 100644
>> > > --- a/kernel/rcu/srcutree.c
>> > > +++ b/kernel/rcu/srcutree.c
>> > > @@ -531,7 +531,6 @@ static void srcu_gp_end(struct srcu_struct *sp)
>> > >       unsigned long flags;
>> > >       unsigned long gpseq;
>> > >       int idx;
>> > > -     int idxnext;
>> > >       unsigned long mask;
>> > >       struct srcu_data *sdp;
>> > >       struct srcu_node *snp;
>> > > @@ -555,7 +554,6 @@ static void srcu_gp_end(struct srcu_struct *sp)
>> > >
>> > >       /* Initiate callback invocation as needed. */
>> > >       idx = rcu_seq_ctr(gpseq) % ARRAY_SIZE(snp->srcu_have_cbs);
>> > > -     idxnext = (idx + 1) % ARRAY_SIZE(snp->srcu_have_cbs);
>> > >       rcu_for_each_node_breadth_first(sp, snp) {
>> > >               spin_lock_irq_rcu_node(snp);
>> > >               cbs = false;
>> > > --
>> > > 2.1.4
>> > >
>> >
>> >
>