linux-kernel - [RFC PATCH v2 8/9] smp: refactor on_each

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Date:	Sun,  8 Jan 2012 15:32:28 +0200
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	linux-kernel@...r.kernel.org
Cc:	Gilad Ben-Yossef <gilad@...yossef.com>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	linuxppc-dev@...ts.ozlabs.org, devicetree-discuss@...ts.ozlabs.org,
	Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Matt Turner <mattst88@...il.com>, linux-alpha@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>, linux-ia64@...r.kernel.org,
	Will Deacon <will.deacon@....com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: [RFC PATCH v2 8/9] smp: refactor on_each_cpu to void returning func

on_each_cpu returns the retunr value of smp_call_function
which is hard coded to 0.

Refactor on_each_cpu to a void function and the few callers
that check the return value to save compares and branches.

Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Reviewed-by: Michal Nazarewicz <mina86@...a86.com>
CC: David Airlie <airlied@...ux.ie>
CC: dri-devel@...ts.freedesktop.org
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC: Paul Mackerras <paulus@...ba.org>
CC: Grant Likely <grant.likely@...retlab.ca>
CC: Rob Herring <rob.herring@...xeda.com>
CC: linuxppc-dev@...ts.ozlabs.org
CC: devicetree-discuss@...ts.ozlabs.org
CC: Richard Henderson <rth@...ddle.net>
CC: Ivan Kokshaysky <ink@...assic.park.msu.ru>
CC: Matt Turner <mattst88@...il.com>
CC: linux-alpha@...r.kernel.org
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: x86@...nel.org
CC: Tony Luck <tony.luck@...el.com>
CC: Fenghua Yu <fenghua.yu@...el.com>
CC: linux-ia64@...r.kernel.org
CC: Will Deacon <will.deacon@....com>
CC: Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC: Russell King <linux@....linux.org.uk>
CC: linux-arm-kernel@...ts.infradead.org
---
 include/linux/smp.h |    7 +++----
 kernel/smp.c        |    6 ++----
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 8cc38d3..050ddd4 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -99,7 +99,7 @@ static inline void call_function_init(void) { }
 /*
  * Call a function on all processors
  */
-int on_each_cpu(smp_call_func_t func, void *info, int wait);
+void on_each_cpu(smp_call_func_t func, void *info, int wait);
 
 /*
  * Mark the boot cpu "online" so that it can call console drivers in
@@ -126,12 +126,11 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info)
 #define smp_call_function(func, info, wait) \
 			(up_smp_call_function(func, info))
 #define on_each_cpu(func,info,wait)		\
-	({					\
+	{					\
 		local_irq_disable();		\
 		func(info);			\
 		local_irq_enable();		\
-		0;				\
-	})
+	}
 static inline void smp_send_reschedule(int cpu) { }
 #define num_booting_cpus()			1
 #define smp_prepare_boot_cpu()			do {} while (0)
diff --git a/kernel/smp.c b/kernel/smp.c
index db197d6..f66a1b2 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -687,17 +687,15 @@ void __init smp_init(void)
  * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
  * of local_irq_disable/enable().
  */
-int on_each_cpu(void (*func) (void *info), void *info, int wait)
+void on_each_cpu(void (*func) (void *info), void *info, int wait)
 {
 	unsigned long flags;
-	int ret = 0;
 
 	preempt_disable();
-	ret = smp_call_function(func, info, wait);
+	smp_call_function(func, info, wait);
 	local_irq_save(flags);
 	func(info);
 	local_irq_restore(flags);
 	preempt_enable();
-	return ret;
 }
 EXPORT_SYMBOL(on_each_cpu);
-- 
1.7.0.4

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