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Subject[cpuops UPDATED 1/9] percpu: Generic support for this_cpu_add,sub,dec,inc_return
From: Christoph Lameter <cl@linux.com>
Subject: percpu: Generic support for this_cpu_add, sub, dec, inc_return

Introduce generic support for this_cpu_add_return etc.

The fallback is to realize these operations with simpler __this_cpu_ops.

tj: - Reformatted __cpu_size_call_return2() to make it more consistent
with its neighbors.

- Dropped unnecessary temp variable ret__ from
__this_cpu_generic_add_return().

Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
I updated it a bit. If you don't like it, please scream.
Thanks.

include/linux/percpu.h | 71 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 71 insertions(+)
Index: percpu/include/linux/percpu.h
===================================================================
--- percpu.orig/include/linux/percpu.h
+++ percpu/include/linux/percpu.h
@@ -240,6 +240,21 @@ extern void __bad_size_call_parameter(vo
pscr_ret__; \
})

+#define __pcpu_size_call_return2(stem, variable, ...) \
+({ \
+ typeof(variable) pscr2_ret__; \
+ __verify_pcpu_ptr(&(variable)); \
+ switch(sizeof(variable)) { \
+ case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \
+ case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \
+ case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \
+ case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \
+ default: \
+ __bad_size_call_parameter(); break; \
+ } \
+ pscr2_ret__; \
+})
+
#define __pcpu_size_call(stem, variable, ...) \
do { \
__verify_pcpu_ptr(&(variable)); \
@@ -529,6 +544,62 @@ do { \
# define __this_cpu_xor(pcp, val) __pcpu_size_call(__this_cpu_xor_, (pcp), (val))
#endif

+#define _this_cpu_generic_add_return(pcp, val) \
+({ \
+ typeof(pcp) ret__; \
+ preempt_disable(); \
+ __this_cpu_add(pcp, val); \
+ ret__ = __this_cpu_read(pcp); \
+ preempt_enable(); \
+ ret__; \
+})
+
+#ifndef this_cpu_add_return
+# ifndef this_cpu_add_return_1
+# define this_cpu_add_return_1(pcp, val) _this_cpu_generic_add_return(pcp, val)
+# endif
+# ifndef this_cpu_add_return_2
+# define this_cpu_add_return_2(pcp, val) _this_cpu_generic_add_return(pcp, val)
+# endif
+# ifndef this_cpu_add_return_4
+# define this_cpu_add_return_4(pcp, val) _this_cpu_generic_add_return(pcp, val)
+# endif
+# ifndef this_cpu_add_return_8
+# define this_cpu_add_return_8(pcp, val) _this_cpu_generic_add_return(pcp, val)
+# endif
+# define this_cpu_add_return(pcp, val) __pcpu_size_call_return2(this_cpu_add_return_, pcp, val)
+#endif
+
+#define this_cpu_sub_return(pcp, val) this_cpu_add_return(pcp, -(val))
+#define this_cpu_inc_return(pcp) this_cpu_add_return(pcp, 1)
+#define this_cpu_dec_return(pcp) this_cpu_add_return(pcp, -1)
+
+#define __this_cpu_generic_add_return(pcp, val) \
+({ \
+ __this_cpu_add(pcp, val); \
+ __this_cpu_read(pcp); \
+})
+
+#ifndef __this_cpu_add_return
+# ifndef __this_cpu_add_return_1
+# define __this_cpu_add_return_1(pcp, val) __this_cpu_generic_add_return(pcp, val)
+# endif
+# ifndef __this_cpu_add_return_2
+# define __this_cpu_add_return_2(pcp, val) __this_cpu_generic_add_return(pcp, val)
+# endif
+# ifndef __this_cpu_add_return_4
+# define __this_cpu_add_return_4(pcp, val) __this_cpu_generic_add_return(pcp, val)
+# endif
+# ifndef __this_cpu_add_return_8
+# define __this_cpu_add_return_8(pcp, val) __this_cpu_generic_add_return(pcp, val)
+# endif
+# define __this_cpu_add_return(pcp, val) __pcpu_size_call_return2(this_cpu_add_return_, pcp, val)
+#endif
+
+#define __this_cpu_sub_return(pcp, val) this_cpu_add_return(pcp, -(val))
+#define __this_cpu_inc_return(pcp) this_cpu_add_return(pcp, 1)
+#define __this_cpu_dec_return(pcp) this_cpu_add_return(pcp, -1)
+
/*
* IRQ safe versions of the per cpu RMW operations. Note that these operations
* are *not* safe against modification of the same variable from another

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