Patch "MIPS: Fix mips_atomic_set() retry condition" has been added to the 4.9-stable tree

Patch "MIPS: Fix mips_atomic_set() retry condition" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    MIPS: Fix mips_atomic_set() retry condition

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-fix-mips_atomic_set-retry-condition.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 2ec420b26f7b6ff332393f0bb5a7d245f7ad87f0 Mon Sep 17 00:00:00 2001
From: James Hogan <james.hogan@imgtec.com>
Date: Wed, 31 May 2017 16:19:47 +0100
Subject: MIPS: Fix mips_atomic_set() retry condition

From: James Hogan <james.hogan@imgtec.com>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/syscall.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -141,7 +141,7 @@ static inline int mips_atomic_set(unsign
 		"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"


Patches currently in stable-queue which might be from james.hogan@imgtec.com are

queue-4.9/mips-send-sigill-for-bposge32-in-__compute_return_epc_for_insn.patch
queue-4.9/mips-actually-decode-jalx-in-__compute_return_epc_for_insn.patch
queue-4.9/mips-fix-mips_atomic_set-retry-condition.patch
queue-4.9/mips-fix-a-typo-s-preset-present-in-r2-to-r6-emulation-error-message.patch
queue-4.9/mips-fix-mips_atomic_set-with-eva.patch
queue-4.9/mips-save-static-registers-before-sysmips.patch
queue-4.9/mips-fix-unaligned-pc-interpretation-in-compute_return_epc.patch
queue-4.9/mips-fix-mips-i-isa-proc-cpuinfo-reporting.patch
queue-4.9/mips-rename-sigill_r6-to-sigill_r2r6-in-__compute_return_epc_for_insn.patch
queue-4.9/mips-negate-error-syscall-return-in-trace.patch
queue-4.9/mips-send-sigill-for-r6-branches-in-__compute_return_epc_for_insn.patch
queue-4.9/mips-send-sigill-for-linked-branches-in-__compute_return_epc_for_insn.patch
queue-4.9/mips-math-emu-prevent-wrong-isa-mode-instruction-emulation.patch