From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: Query regarding srcu_funnel_exp_start()
Date: Fri, 27 Oct 2017 05:26:01 -0700 [thread overview]
Message-ID: <20171027122601.GJ3659@linux.vnet.ibm.com> (raw)
In-Reply-To: <481c3c8d-2385-2e38-dfe6-0cb9b6855b8a@codeaurora.org>
On Fri, Oct 27, 2017 at 02:23:07PM +0530, Neeraj Upadhyay wrote:
> Hi,
>
> One query regarding srcu_funnel_exp_start() function in
> kernel/rcu/srcutree.c.
>
> static void srcu_funnel_exp_start(struct srcu_struct *sp, struct
> srcu_node *snp,
> unsigned long s)
> {
> <snip>
> if (!ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
> sp->srcu_gp_seq_needed_exp = s;
> <snip>
> }
>
> Why is sp->srcu_gp_seq_needed_exp set to 's' if srcu_gp_seq_needed_exp is >=
> 's'. Shouldn't srcu_gp_seq_needed_exp be equal to the greater of both?
Let's suppose that it is incorrect as currently written. Can you
construct a test case demonstrating a failure of some sort, then provide
a fix?
To start with, if it is currently incorrect, what would be the nature
of the failure?
Thanx, Paul
next prev parent reply other threads:[~2017-10-27 12:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-27 8:53 Neeraj Upadhyay
2017-10-27 12:26 ` Paul E. McKenney [this message]
2017-10-27 16:45 ` Neeraj Upadhyay
2017-10-27 22:20 ` Paul E. McKenney
2017-10-28 3:49 ` Neeraj Upadhyay
2017-10-29 19:24 ` Paul E. McKenney
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