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Commit 50952026 authored by Ralf Baechle's avatar Ralf Baechle
Browse files

[MIPS] Fix bug in atomic_sub_if_positive. 



The branch optimization fixes in 2.6.21 introduced a bug in
atomic_sub_if_positive that causes it to return even when the sc
instruction fails. The result is that e.g. down_trylock becomes unreliable
as the semaphore counter is not always decremented.

Original MUA-shredded patch from Morten Larsen <mlarsen@broadcom.com>.

Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent bf9127c3

include/asm-mips/atomic.h

+2 −2
Original line number Diff line number Diff line
@@ -283,10 +283,10 @@ static __inline__ int atomic_sub_if_positive(int i, atomic_t * v) 
		"	beqz	%0, 2f					\n"

		"	 subu	%0, %1, %3				\n"

		"	.set	reorder					\n"

		"1:							\n"

		"	.subsection 2					\n"

		"2:	b	1b					\n"

		"	.previous					\n"

		"1:							\n"

		"	.set	mips0					\n"

		: "=&r" (result), "=&r" (temp), "=m" (v->counter)

		: "Ir" (i), "m" (v->counter)
@@ -664,10 +664,10 @@ static __inline__ long atomic64_sub_if_positive(long i, atomic64_t * v) 
		"	beqz	%0, 2f					\n"

		"	 dsubu	%0, %1, %3				\n"

		"	.set	reorder					\n"

		"1:							\n"

		"	.subsection 2					\n"

		"2:	b	1b					\n"

		"	.previous					\n"

		"1:							\n"

		"	.set	mips0					\n"

		: "=&r" (result), "=&r" (temp), "=m" (v->counter)

		: "Ir" (i), "m" (v->counter)