linux-kernel - [PATCH tip/core/rcu 13/13] rcu: Shrink TINY

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Date:	Mon, 20 May 2013 07:58:20 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, edumazet@...gle.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 13/13] rcu: Shrink TINY_RCU by reworking CPU-stall ifdefs

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

TINY_RCU's reset_cpu_stall_ticks() and check_cpu_stalls() functions
are defined unconditionally, and are empty functions if CONFIG_RCU_TRACE
is disabled (which in turns disables detection of RCU CPU stalls).
These empty functions can add a bit of bloat to TINY_RCU, so this
commit reworks the ifdefs so that these functions are defined only
if they actually do something.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcutiny.c        | 4 ++--
 kernel/rcutiny_plugin.h | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 4adc9e2..aa34411 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -204,7 +204,7 @@ static int rcu_is_cpu_rrupt_from_idle(void)
  */
 static int rcu_qsctr_help(struct rcu_ctrlblk *rcp)
 {
-	reset_cpu_stall_ticks(rcp);
+	RCU_TRACE(reset_cpu_stall_ticks(rcp));
 	if (rcp->rcucblist != NULL &&
 	    rcp->donetail != rcp->curtail) {
 		rcp->donetail = rcp->curtail;
@@ -251,7 +251,7 @@ void rcu_bh_qs(int cpu)
  */
 void rcu_check_callbacks(int cpu, int user)
 {
-	check_cpu_stalls();
+	RCU_TRACE(check_cpu_stalls());
 	if (user || rcu_is_cpu_rrupt_from_idle())
 		rcu_sched_qs(cpu);
 	else if (!in_softirq())
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index 65ef180..0cd385a 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -158,15 +158,11 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp)
 		rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
 }
 
-#endif /* #ifdef CONFIG_RCU_TRACE */
-
 static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
 {
-#ifdef CONFIG_RCU_TRACE
 	rcp->ticks_this_gp = 0;
 	rcp->gp_start = jiffies;
 	rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
-#endif /* #ifdef CONFIG_RCU_TRACE */
 }
 
 static void check_cpu_stalls(void)
@@ -174,3 +170,5 @@ static void check_cpu_stalls(void)
 	RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk));
 	RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk));
 }
+
+#endif /* #ifdef CONFIG_RCU_TRACE */
-- 
1.8.1.5

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