MIPS: Fix mips_atomic_set() retry condition

The inline asm retry check in the MIPS_ATOMIC_SET operation of the
sysmips system call has been backwards since commit f1e39a4a616c ("MIPS:
Rewrite sysmips(MIPS_ATOMIC_SET, ...) in C with inline assembler")
merged in v2.6.32, resulting in the non R10000_LLSC_WAR case retrying
until the operation was inatomic, before returning the new value that
was probably just written multiple times instead of the old value.

Invert the branch condition to fix that particular issue.

Fixes: f1e39a4a616c ("MIPS: Rewrite sysmips(MIPS_ATOMIC_SET, ...) in C with inline assembler")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16148/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index 1dfa7f5796c7c69dea60b531be757419d6780760..95e1b300ac0d00de5af9d29a8c54cdc8e5c8110a 100644 (file)
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -134,7 +134,7 @@ static inline int mips_atomic_set(unsigned long addr, unsigned long new)
                "1:     ll      %[old], (%[addr])                       \n"
                "       move    %[tmp], %[new]                          \n"
                "2:     sc      %[tmp], (%[addr])                       \n"
-               "       bnez    %[tmp], 4f                              \n"
+               "       beqz    %[tmp], 4f                              \n"
                "3:                                                     \n"
                "       .insn                                           \n"
                "       .subsection 2                                   \n"