From: Frederic Weisbecker <frederic@kernel.org>
To: "Zhang, Qiang1" <qiang1.zhang@intel.com>
Cc: "paulmck@kernel.org" <paulmck@kernel.org>,
"quic_neeraju@quicinc.com" <quic_neeraju@quicinc.com>,
"joel@joelfernandes.org" <joel@joelfernandes.org>,
"rcu@vger.kernel.org" <rcu@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] rcu: Fix race in set and clear TICK_DEP_BIT_RCU_EXP bitmask
Date: Tue, 3 Jan 2023 13:13:53 +0100 [thread overview]
Message-ID: <Y7QcAe+l2J3NtRB6@lothringen> (raw)
In-Reply-To: <PH0PR11MB588001E32A306F2166D55622DAF69@PH0PR11MB5880.namprd11.prod.outlook.com>
On Sun, Jan 01, 2023 at 09:41:57AM +0000, Zhang, Qiang1 wrote:
> > > >On Sat, Dec 31, 2022 at 07:25:08PM +0100, Frederic Weisbecker wrote:
>
> Yes, and I have a question, we forcing the tick dependency because the expedited grace period
> is not end for the first time, this means that it is not to set the tick dependency every time.
> if we set the tick dependency in rcu_exp_handler(), does this mean that every time the expedited
> grace period starts the tick dependency will be set unconditionally ?
>
> Thoughts ?
Only if rcu_exp_handler() fails to report a quiescent state. Then it means we
must poll on the CPU looking for a future one.
In fact the tick dependency should be set when rdp->cpu_no_qs.b.exp is set to
true and cleared when rdp->cpu_no_qs.b.exp is set to false.
Thanks.
>
> Thanks
> Zqiang
>
> >
> > Thanx, Paul
prev parent reply other threads:[~2023-01-03 12:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-20 11:25 [PATCH] rcu: Fix race in set and clear TICK_DEP_BIT_RCU_EXP bitmask Zqiang
2022-12-21 20:08 ` Paul E. McKenney
2022-12-22 9:48 ` Zhang, Qiang1
2022-12-22 15:18 ` Paul E. McKenney
2022-12-31 18:25 ` Frederic Weisbecker
2022-12-31 19:01 ` Paul E. McKenney
2023-01-01 9:41 ` Zhang, Qiang1
2023-01-03 12:13 ` Frederic Weisbecker [this message]
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