From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 10/21] rcu/nocb: Set SEGCBLIST_SOFTIRQ_ONLY at the very last stage of de-offloading
Date: Tue, 5 Jan 2021 20:48:42 -0800 [thread overview]
Message-ID: <20210106044853.20812-10-paulmck@kernel.org> (raw)
In-Reply-To: <20210106013950.GA14663@paulmck-ThinkPad-P72>
From: Frederic Weisbecker <frederic@kernel.org>
This commit sets SEGCBLIST_SOFTIRQ_ONLY once toggling is otherwise fully
complete, allowing further RCU callback manipulation to be carried out
locklessly and locally.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree_plugin.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 35dc9b3..8641b72 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2352,7 +2352,14 @@ static int __rcu_nocb_rdp_deoffload(struct rcu_data *rdp)
*/
rcu_nocb_lock_irqsave(rdp, flags);
rcu_nocb_flush_bypass(rdp, NULL, jiffies);
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ rcu_segcblist_set_flags(cblist, SEGCBLIST_SOFTIRQ_ONLY);
+ /*
+ * With SEGCBLIST_SOFTIRQ_ONLY, we can't use
+ * rcu_nocb_unlock_irqrestore() anymore. Theoretically we
+ * could set SEGCBLIST_SOFTIRQ_ONLY with cb unlocked and IRQs
+ * disabled now, but let's be paranoid.
+ */
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
return ret;
}
--
2.9.5
next prev parent reply other threads:[~2021-01-06 4:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 1:39 [PATCH tip/core/rcu 0/21] Provide runtime switching of offloaded CPUs Paul E. McKenney
2021-01-06 4:48 ` [PATCH tip/core/rcu 01/21] rcu/nocb: Turn enabled/offload states into a common flag paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 02/21] rcu/nocb: Provide basic callback offloading state machine bits paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 03/21] rcu/nocb: Always init segcblist on CPU up paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 04/21] rcu/nocb: De-offloading CB kthread paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 05/21] rcu/nocb: Don't deoffload an offline CPU with pending work paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 06/21] rcu/nocb: De-offloading GP kthread paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 07/21] rcu/nocb: Re-offload support paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 08/21] rcu/nocb: Shutdown nocb timer on de-offloading paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 09/21] rcu/nocb: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY paulmck
2021-01-06 4:48 ` paulmck [this message]
2021-01-06 4:48 ` [PATCH tip/core/rcu 11/21] rcu/nocb: Only cond_resched() from actual offloaded batch processing paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 12/21] rcu/nocb: Process batch locally as long as offloading isn't complete paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 13/21] rcu/nocb: Locally accelerate callbacks " paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 14/21] cpu/hotplug: Add lockdep_is_cpus_held() paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 15/21] timer: Add timer_curr_running() paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 16/21] rcutorture: Test runtime toggling of CPUs' callback offloading paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 17/21] tools/rcutorture: Support nocb toggle in TREE01 paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 18/21] rcu/nocb: Add grace period and task state to show_rcu_nocb_state() output paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 19/21] rcu/nocb: Add nocb CB kthread list " paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 20/21] rcu/nocb: Code-style nits in callback-offloading toggling paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 21/21] rcu: Do any deferred nocb wakeups at CPU offline time paulmck
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