s390/percpu: add READ_ONCE() to arch_this_cpu_to_op_simple()

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: <[email protected]> Reviewed-by: Alexander Gordeev <[email protected]> Signed-off-by: Heiko Carstens <[email protected]>
wafgo · Jan 11, 2023 · e3f360d · e3f360d
1 parent 82d3edb
commit e3f360d
Showing 1 changed file with 1 addition and 1 deletion.
diff --git 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);					\