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Date: Sun, 12 Dec 2004 22:32:49 -0800
From: Andrew Morton <akpm@osdl.org>
To: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Cc: paulmck@us.ibm.com, sfr@canb.auug.org.au, linux-kernel@vger.kernel.org,
       dipankar@in.ibm.com, shaohua.li@intel.com, len.brown@intel.com
Subject: Re: [PATCH] Remove RCU abuse in cpu_idle()
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Zwane Mwaikambo <zwane@arm.linux.org.uk> wrote:
>
> The idle thread is special in the sense that it can't get migrated so the 
>  cached values of smp_processor_id are fine.

duh, knew that.

We can use the cached value throughout, no?

--- 25/arch/i386/kernel/process.c~remove-rcu-abuse-in-cpu_idle-warning-fix	2004-12-12 22:30:10.200626944 -0800
+++ 25-akpm/arch/i386/kernel/process.c	2004-12-12 22:31:22.417648288 -0800
@@ -146,7 +146,7 @@ static void poll_idle (void)
  */
 void cpu_idle (void)
 {
-	int cpu = smp_processor_id();
+	int cpu = _smp_processor_id();
 
 	/* endless idle loop with no priority at all */
 	while (1) {
@@ -161,7 +161,7 @@ void cpu_idle (void)
 			if (!idle)
 				idle = default_idle;
 
-			irq_stat[smp_processor_id()].idle_timestamp = jiffies;
+			irq_stat[cpu].idle_timestamp = jiffies;
 			idle();
 		}
 		schedule();
_