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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.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 v2 tip/core/rcu 03/14] rcu: Simplify rcu_sched_qs() control flow
Date: Wed,  9 Dec 2015 15:10:01 -0800	[thread overview]
Message-ID: <1449702612-1661-3-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20151209230940.GA1251@linux.vnet.ibm.com>

This commit applies an early-exit approach to rcu_sched_qs(), reducing
the nesting level and saving a line of code.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 23df2661c899..ed3bc0578cc5 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -244,22 +244,21 @@ void rcu_sched_qs(void)
 {
 	unsigned long flags;
 
-	if (__this_cpu_read(rcu_sched_data.cpu_no_qs.s)) {
-		trace_rcu_grace_period(TPS("rcu_sched"),
-				       __this_cpu_read(rcu_sched_data.gpnum),
-				       TPS("cpuqs"));
-		__this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
-		if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
-			return;
-		local_irq_save(flags);
-		if (__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp)) {
-			__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, false);
-			rcu_report_exp_rdp(&rcu_sched_state,
-					   this_cpu_ptr(&rcu_sched_data),
-					   true);
-		}
-		local_irq_restore(flags);
+	if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.s))
+		return;
+	trace_rcu_grace_period(TPS("rcu_sched"),
+			       __this_cpu_read(rcu_sched_data.gpnum),
+			       TPS("cpuqs"));
+	__this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
+	if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
+		return;
+	local_irq_save(flags);
+	if (__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp)) {
+		__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, false);
+		rcu_report_exp_rdp(&rcu_sched_state,
+				   this_cpu_ptr(&rcu_sched_data), true);
 	}
+	local_irq_restore(flags);
 }
 
 void rcu_bh_qs(void)
-- 
2.5.2


  parent reply	other threads:[~2015-12-09 23:10 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-09 23:09 [PATCH v2 tip/core/rcu 0/14] Miscellaneous fixes for 4.5 Paul E. McKenney
2015-12-09 23:09 ` [PATCH v2 tip/core/rcu 01/14] rcu: Move lock_class_key to local scope Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 02/14] kernel: Make rcu/tree_trace.c explicitly non-modular Paul E. McKenney
2015-12-09 23:10 ` Paul E. McKenney [this message]
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 04/14] rcu: Remove lock-acquisition loop from rcu_read_unlock_special() Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 05/14] rcu: Fix obsolete rcu_bootup_announce_oddness() comment Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 06/14] rcu: Avoid tick_nohz_active checks on NOCBs CPUs Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 07/14] rcu: Stop disabling interrupts in scheduler fastpaths Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 08/14] rcu: Eliminate unused rcu_init_one() argument Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 09/14] rcu: Make cpu_needs_another_gp() be bool Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 10/14] rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}() Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 11/14] rcu: Fix comment for rcu_dereference_raw_notrace Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 12/14] rcu: Move wakeup out from under rnp->lock Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 13/14] rcu: Make rcu_gp_init() be bool rather than int Paul E. McKenney
2015-12-09 23:10 ` [PATCH v2 tip/core/rcu 14/14] list: Add lockless list traversal primitives Paul E. McKenney

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