This is a note to let you know that I've just added the patch titled
s390/percpu: add READ_ONCE() to arch_this_cpu_to_op_simple()
to the 4.19-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:
s390-percpu-add-read_once-to-arch_this_cpu_to_op_simple.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e3f360db08d55a14112bd27454e616a24296a8b0 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@xxxxxxxxxxxxx>
Date: Mon, 9 Jan 2023 11:51:20 +0100
Subject: s390/percpu: add READ_ONCE() to arch_this_cpu_to_op_simple()
From: Heiko Carstens <hca@xxxxxxxxxxxxx>
commit e3f360db08d55a14112bd27454e616a24296a8b0 upstream.
Make sure that *ptr__ within arch_this_cpu_to_op_simple() is only
dereferenced once by using READ_ONCE(). Otherwise the compiler could
generate incorrect code.
Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/percpu.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/include/asm/percpu.h
+++ b/arch/s390/include/asm/percpu.h
@@ -31,7 +31,7 @@
pcp_op_T__ *ptr__; \
preempt_disable_notrace(); \
ptr__ = raw_cpu_ptr(&(pcp)); \
- prev__ = *ptr__; \
+ prev__ = READ_ONCE(*ptr__); \
do { \
old__ = prev__; \
new__ = old__ op (val); \
Patches currently in stable-queue which might be from hca@xxxxxxxxxxxxx are
queue-4.19/s390-percpu-add-read_once-to-arch_this_cpu_to_op_simple.patch
