Commit 8aef36da authored by Al Viro's avatar Al Viro
Browse files

x86: don't reload after cmpxchg in unsafe_atomic_op2() loop 



lock cmpxchg leaves the current value in eax; no need to reload it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 0ec33c01

arch/x86/include/asm/futex.h

+8 −8
Original line number Diff line number Diff line
@@ -34,17 +34,17 @@ do { \ 
do {								\

	int oldval = 0, ret, tem;				\

	asm volatile("1:\tmovl	%2, %0\n"			\

		     "\tmovl\t%0, %3\n"				\

		     "2:\tmovl\t%0, %3\n"			\

		     "\t" insn "\n"				\

		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\

		     "\tjnz\t1b\n"				\

		     "3:\n"					\

		     "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\

		     "\tjnz\t2b\n"				\

		     "4:\n"					\

		     "\t.section .fixup,\"ax\"\n"		\

		     "4:\tmov\t%5, %1\n"			\

		     "\tjmp\t3b\n"				\

		     "5:\tmov\t%5, %1\n"			\

		     "\tjmp\t4b\n"				\

		     "\t.previous\n"				\

		     _ASM_EXTABLE_UA(1b, 4b)			\

		     _ASM_EXTABLE_UA(2b, 4b)			\

		     _ASM_EXTABLE_UA(1b, 5b)			\

		     _ASM_EXTABLE_UA(3b, 5b)			\

		     : "=&a" (oldval), "=&r" (ret),		\

		       "+m" (*uaddr), "=&r" (tem)		\

		     : "r" (oparg), "i" (-EFAULT), "1" (0));	\

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