linux-kernel - [PATCH] i386: avoid redundant preempt_disable in __unlazy

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Date:	Mon, 30 Apr 2007 13:16:42 +0200
From:	Jan Kiszka <jan.kiszka@....de>
To:	linux-kernel@...r.kernel.org
CC:	Andi Kleen <ak@...e.de>
Subject: [PATCH] i386: avoid redundant preempt_disable in __unlazy_fpu

There are two callers of __unlazy_fpu, unlazy_fpu and __switch_to, and
none of them appear to require additional preempt_disable/enable here.
Let's open-code save_init_fpu in __unlazy_fpu to save a few ops.

Signed-off-by: Jan Kiszka <jan.kiszka@....de>

---
 include/asm-i386/i387.h |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Index: linux-2.6/include/asm-i386/i387.h
===================================================================
--- linux-2.6.orig/include/asm-i386/i387.h
+++ linux-2.6/include/asm-i386/i387.h
@@ -74,11 +74,12 @@ static inline void __save_init_fpu( stru
 	task_thread_info(tsk)->status &= ~TS_USEDFPU;
 }
 
-#define __unlazy_fpu( tsk ) do { \
-	if (task_thread_info(tsk)->status & TS_USEDFPU) \
-		save_init_fpu( tsk ); 			\
-	else						\
-		tsk->fpu_counter = 0;			\
+#define __unlazy_fpu( tsk ) do {				\
+	if (task_thread_info(tsk)->status & TS_USEDFPU) {	\
+		__save_init_fpu(tsk);				\
+		stts();						\
+	} else							\
+		tsk->fpu_counter = 0;				\
 } while (0)
 
 #define __clear_fpu( tsk )					\


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