From: Ralf Baechle <ralf@linux-mips.org>
To: Thomas Koeller <thomas.koeller@baslerweb.com>
Cc: linux-mips@linux-mips.org
Subject: Re: [PATCH] atomic functions broken
Date: Thu, 23 Feb 2006 14:09:47 +0000 [thread overview]
Message-ID: <20060223140947.GB6272@linux-mips.org> (raw)
In-Reply-To: <200602222125.39999.thomas.koeller@baslerweb.com>
On Wed, Feb 22, 2006 at 09:25:39PM +0100, Thomas Koeller wrote:
> The ll/sc versions of atomic_sub_if_positive(), and the corresponding 64-bit functions,
> are broken. The value returned by those functions is always one, no matter what.
Good catch - and I wonder how you found this bug since it didn't seem to
cause any obvious damage. I just went for a different fix though - I was
able to get away without an extra register and squeeze the needed extra
instruction into a delay slot, so no code size penalty either.
Ralf
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
--- a/include/asm-mips/atomic.h
+++ b/include/asm-mips/atomic.h
@@ -250,7 +250,10 @@ static __inline__ int atomic_sub_if_posi
" subu %0, %1, %3 \n"
" bltz %0, 1f \n"
" sc %0, %2 \n"
+ " .set noreorder \n"
" beqzl %0, 1b \n"
+ " subu %0, %1, %3 \n"
+ " .set reorder \n"
" sync \n"
"1: \n"
" .set mips0 \n"
@@ -266,7 +269,10 @@ static __inline__ int atomic_sub_if_posi
" subu %0, %1, %3 \n"
" bltz %0, 1f \n"
" sc %0, %2 \n"
+ " .set noreorder \n"
" beqz %0, 1b \n"
+ " subu %0, %1, %3 \n"
+ " .set reorder \n"
" sync \n"
"1: \n"
" .set mips0 \n"
@@ -598,7 +604,10 @@ static __inline__ long atomic64_sub_if_p
" dsubu %0, %1, %3 \n"
" bltz %0, 1f \n"
" scd %0, %2 \n"
+ " .set noreorder \n"
" beqzl %0, 1b \n"
+ " dsubu %0, %1, %3 \n"
+ " .set reorder \n"
" sync \n"
"1: \n"
" .set mips0 \n"
@@ -614,7 +623,10 @@ static __inline__ long atomic64_sub_if_p
" dsubu %0, %1, %3 \n"
" bltz %0, 1f \n"
" scd %0, %2 \n"
+ " .set noreorder \n"
" beqz %0, 1b \n"
+ " dsubu %0, %1, %3 \n"
+ " .set reorder \n"
" sync \n"
"1: \n"
" .set mips0 \n"
prev parent reply other threads:[~2006-02-23 14:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-22 20:25 [PATCH] atomic functions broken Thomas Koeller
2006-02-23 14:09 ` Ralf Baechle [this message]
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