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>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 5095b83..4d593de 100644 (file)
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -240,6 +240,21 @@ extern void __bad_size_call_parameter(void);
        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