[PATCH v6 02/12] this_cpu_cmpxchg: loongarch: switch this_cpu_cmpxchg to locked, add _local function

[Marcelo Tosatti]

Goal is to have vmstat_shepherd to transfer from
per-CPU counters to global counters remotely. For this,
an atomic this_cpu_cmpxchg is necessary.

Following the kernel convention for cmpxchg/cmpxchg_local,
add this_cpu_cmpxchg_local helpers to Loongarch.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

Index: linux-vmstat-remote/arch/loongarch/include/asm/percpu.h
===================================================================
--- linux-vmstat-remote.orig/arch/loongarch/include/asm/percpu.h
+++ linux-vmstat-remote/arch/loongarch/include/asm/percpu.h
@@ -150,6 +150,16 @@ static inline unsigned long __percpu_xch
 }
 
 /* this_cpu_cmpxchg */
+#define _protect_cmpxchg(pcp, o, n)				\
+({								\
+	typeof(*raw_cpu_ptr(&(pcp))) __ret;			\
+	preempt_disable_notrace();				\
+	__ret = cmpxchg(raw_cpu_ptr(&(pcp)), o, n);		\
+	preempt_enable_notrace();				\
+	__ret;							\
+})
+
+/* this_cpu_cmpxchg_local */
 #define _protect_cmpxchg_local(pcp, o, n)			\
 ({								\
 	typeof(*raw_cpu_ptr(&(pcp))) __ret;			\
@@ -222,10 +232,15 @@ do {									\
 #define this_cpu_xchg_4(pcp, val) _percpu_xchg(pcp, val)
 #define this_cpu_xchg_8(pcp, val) _percpu_xchg(pcp, val)
 
-#define this_cpu_cmpxchg_1(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
-#define this_cpu_cmpxchg_2(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
-#define this_cpu_cmpxchg_4(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
-#define this_cpu_cmpxchg_8(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
+#define this_cpu_cmpxchg_local_1(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
+#define this_cpu_cmpxchg_local_2(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
+#define this_cpu_cmpxchg_local_4(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
+#define this_cpu_cmpxchg_local_8(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
+
+#define this_cpu_cmpxchg_1(ptr, o, n) _protect_cmpxchg(ptr, o, n)
+#define this_cpu_cmpxchg_2(ptr, o, n) _protect_cmpxchg(ptr, o, n)
+#define this_cpu_cmpxchg_4(ptr, o, n) _protect_cmpxchg(ptr, o, n)
+#define this_cpu_cmpxchg_8(ptr, o, n) _protect_cmpxchg(ptr, o, n)
 
 #include <asm-generic/percpu.h>