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
next prev parent reply other threads:[~2015-05-12 21:50 UTC|newest]
Thread overview: 15+ 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
2015-05-21 8:58 ` Will Deacon
2015-05-21 12:48 ` Paul E. McKenney
2015-05-21 13:25 ` Catalin Marinas
2015-05-22 3:26 ` Paul E. McKenney
2015-05-12 21:50 ` [PATCH tip/core/rcu 8/9] arm: " Paul E. McKenney
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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