linux-kernel - Straggler: Connector: Use this_cpu

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Message-ID: <alpine.DEB.2.00.1012070945150.26552@router.home>
Date:	Tue, 7 Dec 2010 09:46:29 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Tejun Heo <tj@...nel.org>
cc:	akpm@...ux-foundation.org, Pekka Enberg <penberg@...helsinki.fi>,
	linux-kernel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Straggler: Connector: Use this_cpu_operations

The patch was originally in the use cpuops patchset but it needs an
inc_return and is therefore dependant on an extension of the cpu ops.
Fixed up and verified that it compiles.


Subject: Connector: Use this_cpu operations

get_seq can benefit from this_cpu_operations. Address calculation is avoided
and the increment is done using an xadd.

Cc: Scott James Remnant <scott@...ntu.com>
Cc: Mike Frysinger <vapier@...too.org>
Signed-off-by: Christoph Lameter <cl@...ux.com>

---
 drivers/connector/cn_proc.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/connector/cn_proc.c
===================================================================
--- linux-2.6.orig/drivers/connector/cn_proc.c	2010-12-07 09:40:48.000000000 -0600
+++ linux-2.6/drivers/connector/cn_proc.c	2010-12-07 09:41:13.000000000 -0600
@@ -43,9 +43,10 @@ static DEFINE_PER_CPU(__u32, proc_event_

 static inline void get_seq(__u32 *ts, int *cpu)
 {
-	*ts = get_cpu_var(proc_event_counts)++;
+	preempt_disable();
+	*ts = __this_cpu_inc_return(proc_event_counts) -1;
 	*cpu = smp_processor_id();
-	put_cpu_var(proc_event_counts);
+	preempt_enable();
 }

 void proc_fork_connector(struct task_struct *task)

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