From: "Paul E. McKenney" <paulmck@kernel.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
Josh Triplett <josh@joshtriplett.org>,
Stable <stable@vger.kernel.org>,
Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH 07/16] rcu/nocb: Rename nocb_gp_update_state to nocb_gp_update_state_deoffloading
Date: Thu, 28 Jan 2021 16:49:44 -0800 [thread overview]
Message-ID: <20210129004944.GZ2743@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20210128171222.131380-8-frederic@kernel.org>
On Thu, Jan 28, 2021 at 06:12:13PM +0100, Frederic Weisbecker wrote:
> Unconfuse a bit the name of this function which suggests returning true
> when the state is updated. It actually returns true when the rdp is in
> the process of deoffloading and we must ignore it.
>
> Reported-by: Paul E. McKenney <paulmck@kernel.org>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> Cc: Joel Fernandes <joel@joelfernandes.org>
> Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Fair point, thank you! I have queued this one for further review and
testing, with the usual wordsmithing shown below.
Thanx, Paul
------------------------------------------------------------------------
commit 142d159f544763140e0f498936bca8f71563e0e0
Author: Frederic Weisbecker <frederic@kernel.org>
Date: Thu Jan 28 18:12:13 2021 +0100
rcu/nocb: Rename nocb_gp_update_state to nocb_gp_update_state_deoffloading
The name nocb_gp_update_state() is unenlightening, so this commit changes
it to nocb_gp_update_state_deoffloading(). This function now does what
its name says, updates state and returns true if the CPU corresponding to
the specified rcu_data structure is in the process of being de-offloaded.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index a3db700..9c0ee82 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2014,7 +2014,8 @@ static inline bool nocb_gp_enabled_cb(struct rcu_data *rdp)
return rcu_segcblist_test_flags(&rdp->cblist, flags);
}
-static inline bool nocb_gp_update_state(struct rcu_data *rdp, bool *needwake_state)
+static inline bool nocb_gp_update_state_deoffloading(struct rcu_data *rdp,
+ bool *needwake_state)
{
struct rcu_segcblist *cblist = &rdp->cblist;
@@ -2024,7 +2025,7 @@ static inline bool nocb_gp_update_state(struct rcu_data *rdp, bool *needwake_sta
if (rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB))
*needwake_state = true;
}
- return true;
+ return false;
}
/*
@@ -2035,7 +2036,7 @@ static inline bool nocb_gp_update_state(struct rcu_data *rdp, bool *needwake_sta
rcu_segcblist_clear_flags(cblist, SEGCBLIST_KTHREAD_GP);
if (!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB))
*needwake_state = true;
- return false;
+ return true;
}
@@ -2073,7 +2074,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
continue;
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
rcu_nocb_lock_irqsave(rdp, flags);
- if (!nocb_gp_update_state(rdp, &needwake_state)) {
+ if (nocb_gp_update_state_deoffloading(rdp, &needwake_state)) {
rcu_nocb_unlock_irqrestore(rdp, flags);
if (needwake_state)
swake_up_one(&rdp->nocb_state_wq);
next prev parent reply other threads:[~2021-01-29 0:51 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 17:12 [PATCH 00/16] rcu/nocb updates Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 01/16] rcu/nocb: Fix potential missed nocb_timer rearm Frederic Weisbecker
[not found] ` <20210128184834.GP2743@paulmck-ThinkPad-P72>
2021-01-28 21:23 ` Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 02/16] rcu/nocb: Comment the reason behind BH disablement on batch processing Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 03/16] rcu/nocb: Forbid NOCB toggling on offline CPUs Frederic Weisbecker
2021-01-28 19:52 ` Paul E. McKenney
2021-01-28 17:12 ` [PATCH 04/16] rcu/nocb: Only (re-)initialize segcblist when needed on CPU up Frederic Weisbecker
[not found] ` <20210128191228.GQ2743@paulmck-ThinkPad-P72>
2021-01-28 21:34 ` Frederic Weisbecker
2021-01-28 21:45 ` Paul E. McKenney
2021-01-29 0:26 ` Paul E. McKenney
2021-01-28 17:12 ` [PATCH 05/16] rcu/nocb: Disable bypass when CPU isn't completely offloaded Frederic Weisbecker
2021-01-28 21:31 ` Paul E. McKenney
2021-01-28 22:25 ` Frederic Weisbecker
2021-01-29 0:19 ` Paul E. McKenney
2021-01-28 17:12 ` [PATCH 06/16] rcu/nocb: Avoid confusing double write of rdp->nocb_cb_sleep Frederic Weisbecker
2021-01-28 21:42 ` Paul E. McKenney
2021-01-28 17:12 ` [PATCH 07/16] rcu/nocb: Rename nocb_gp_update_state to nocb_gp_update_state_deoffloading Frederic Weisbecker
2021-01-29 0:49 ` Paul E. McKenney [this message]
2021-01-28 17:12 ` [PATCH 08/16] rcu/nocb: Move trace_rcu_nocb_wake() calls outside nocb_lock when possible Frederic Weisbecker
2021-01-29 0:51 ` Paul E. McKenney
2021-01-28 17:12 ` [PATCH 09/16] rcu/nocb: Merge nocb_timer to the rdp leader Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 10/16] rcu/nocb: Directly call __wake_nocb_gp() from bypass timer Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 11/16] rcu/nocb: Allow de-offloading rdp leader Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 12/16] rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 13/16] rcu/nocb: Delete bypass_timer " Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 14/16] rcu/nocb: Only cancel nocb timer if not polling Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 15/16] rcu/nocb: Prepare for finegrained deferred wakeup Frederic Weisbecker
2021-01-28 17:12 ` [PATCH 16/16] rcu/nocb: Unify timers Frederic Weisbecker
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