MIPS: Fix mips_atomic_set() retry condition

commit 2ec420b26f7b6ff332393f0bb5a7d245f7ad87f0 upstream.

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
Patchwork: https://patchwork.linux-mips.org/patch/16148/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index 4a4f9dda5658af8297b66981532c01f288609306..4b88ba95dfa01404155bd06c4dce79b78bd440d2 100644 (file)
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -140,7 +140,7 @@ 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"
                "       .subsection 2                                   \n"
                "4:     b       1b                                      \n"