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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.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,
	dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
	bobby.prani@gmail.com,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 4/9] rcu: Remove redundant offline check
Date: Tue, 12 May 2015 14:50:02 -0700	[thread overview]
Message-ID: <1431467407-1223-4-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <1431467407-1223-1-git-send-email-paulmck@linux.vnet.ibm.com>

From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

Because offline CPUs are propagated up the rcu_node tree's ->qsmaskinit
bits just before each grace period starts, the ->qsmaskinit bit cannot
be clear when the corresponding ->qsmask bit is set.  Furthermore, this
condition used to correspond to a CPU that was on its way offline, and
making RCU's notion of an offline CPU more precise has eliminated this
situation.  This commit therefore removes the now-redundant offline
check from force_qs_rnp().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 20aeb6f9fe38..1eb1029a5464 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2747,8 +2747,6 @@ static void force_qs_rnp(struct rcu_state *rsp,
 		bit = 1;
 		for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
 			if ((rnp->qsmask & bit) != 0) {
-				if ((rnp->qsmaskinit & bit) == 0)
-					*isidle = false; /* Pending hotplug. */
 				if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
 					mask |= bit;
 			}
-- 
1.8.1.5


  parent reply	other threads:[~2015-05-12 21:50 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-12 21:49 [PATCH tip/core/rcu 0/9] CPU-hotplug updates for 4.2 Paul E. McKenney
2015-05-12 21:49 ` [PATCH tip/core/rcu 1/9] rcu: Eliminate HOTPLUG_CPU #ifdef in favor of IS_ENABLED() Paul E. McKenney
2015-05-12 21:50   ` [PATCH tip/core/rcu 2/9] rcu: Adjust ->lock acquisition for tasks no longer migrating Paul E. McKenney
2015-05-12 21:50   ` [PATCH tip/core/rcu 3/9] rcu: Remove dead code from force_qs_rnp() Paul E. McKenney
2015-05-12 21:50   ` Paul E. McKenney [this message]
2015-05-12 21:50   ` [PATCH tip/core/rcu 5/9] rcu: Correctly initialize ->rcu_qs_ctr_snap at online time Paul E. McKenney
2015-05-12 21:50   ` [PATCH tip/core/rcu 6/9] cpu: Handle smpboot_unpark_threads() uniformly Paul E. McKenney
2015-05-12 21:50   ` [PATCH tip/core/rcu 7/9] arm64: Use common outgoing-CPU-notification code Paul E. McKenney
2015-05-12 21:50     ` Paul E. McKenney
2015-05-21  8:58     ` Will Deacon
2015-05-21  8:58       ` Will Deacon
2015-05-21 12:48       ` Paul E. McKenney
2015-05-21 12:48         ` Paul E. McKenney
2015-05-21 13:25         ` Catalin Marinas
2015-05-21 13:25           ` Catalin Marinas
2015-05-22  3:26           ` Paul E. McKenney
2015-05-22  3:26             ` Paul E. McKenney
2015-05-12 21:50   ` [PATCH tip/core/rcu 8/9] arm: " Paul E. McKenney
2015-05-12 21:50     ` Paul E. McKenney
2015-12-14 12:18     ` Geert Uytterhoeven
2015-12-14 12:18       ` Geert Uytterhoeven
2015-12-14 12:18       ` Geert Uytterhoeven
2015-05-12 21:50   ` [PATCH tip/core/rcu 9/9] cpu: Remove new instance of __cpuinit that crept back in Paul E. McKenney

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