linux-kernel - [PATCH] x86, percpu: Fix __this_cpu

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Date:	Fri, 10 Sep 2010 01:31:04 -0400
From:	Brian Gerst <brgerst@...il.com>
To:	tj@...nel.org
Cc:	linux-kernel@...r.kernel.org,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [PATCH] x86, percpu: Fix __this_cpu_ptr with const pointers

Fix this error when the pointer is marked const:
error: read-only variable 'tcp_ptr__' used as 'asm' output

Signed-off-by: Brian Gerst <brgerst@...il.com>
CC: Stephen Rothwell <sfr@...b.auug.org.au>
---
 arch/x86/include/asm/percpu.h |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index fe418dd..f62b52c 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -54,12 +54,12 @@
  */
 #define __this_cpu_ptr(ptr)				\
 ({							\
-	typeof(ptr) tcp_ptr__ = (ptr);			\
+	unsigned long tcp_ptr__;			\
 	__verify_pcpu_ptr(ptr);				\
 	asm volatile("add " __percpu_arg(1) ", %0"	\
-		     : "+r" (tcp_ptr__)			\
-		     : "m" (this_cpu_off));		\
-	tcp_ptr__;					\
+		     : "=r" (tcp_ptr__)			\
+		     : "m" (this_cpu_off), "0" (ptr));	\
+	(typeof(ptr) __kernel __force) tcp_ptr__;	\
 })
 #else
 #define __percpu_arg(x)		"%P" #x
-- 
1.7.2.2

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