1 #include <linux/module.h>
3 /* validate @native and @pcp counter values match @expected */
4 #define CHECK(native, pcp, expected) \
6 WARN((native) != (expected), \
7 "raw %ld (0x%lx) != expected %lld (0x%llx)", \
9 (long long)(expected), (long long)(expected)); \
10 WARN(__this_cpu_read(pcp) != (expected), \
11 "pcp %ld (0x%lx) != expected %lld (0x%llx)", \
12 __this_cpu_read(pcp), __this_cpu_read(pcp), \
13 (long long)(expected), (long long)(expected)); \
16 static DEFINE_PER_CPU(long, long_counter
);
17 static DEFINE_PER_CPU(unsigned long, ulong_counter
);
19 static int __init
percpu_test_init(void)
22 * volatile prevents compiler from optimizing it uses, otherwise the
23 * +ul_one/-ul_one below would replace with inc/dec instructions.
25 volatile unsigned int ui_one
= 1;
29 pr_info("percpu test start\n");
34 __this_cpu_add(long_counter
, -1);
35 CHECK(l
, long_counter
, -1);
38 __this_cpu_add(long_counter
, 1);
39 CHECK(l
, long_counter
, 0);
42 __this_cpu_write(ulong_counter
, 0);
45 __this_cpu_add(ulong_counter
, 1UL);
46 CHECK(ul
, ulong_counter
, 1);
49 __this_cpu_add(ulong_counter
, -1UL);
50 CHECK(ul
, ulong_counter
, 0);
52 ul
+= -(unsigned long)1;
53 __this_cpu_add(ulong_counter
, -(unsigned long)1);
54 CHECK(ul
, ulong_counter
, -1);
57 __this_cpu_write(ulong_counter
, 0);
60 __this_cpu_dec(ulong_counter
);
61 CHECK(ul
, ulong_counter
, -1);
62 CHECK(ul
, ulong_counter
, ULONG_MAX
);
65 __this_cpu_add(long_counter
, -ui_one
);
66 CHECK(l
, long_counter
, 0xffffffff);
69 __this_cpu_add(long_counter
, ui_one
);
70 CHECK(l
, long_counter
, (long)0x100000000LL
);
74 __this_cpu_write(long_counter
, 0);
77 __this_cpu_sub(long_counter
, ui_one
);
78 CHECK(l
, long_counter
, -1);
81 __this_cpu_write(long_counter
, 0);
84 __this_cpu_add(long_counter
, ui_one
);
85 CHECK(l
, long_counter
, 1);
88 __this_cpu_add(long_counter
, -ui_one
);
89 CHECK(l
, long_counter
, (long)0x100000000LL
);
92 __this_cpu_write(long_counter
, 0);
95 this_cpu_sub(long_counter
, ui_one
);
96 CHECK(l
, long_counter
, -1);
97 CHECK(l
, long_counter
, ULONG_MAX
);
100 __this_cpu_write(ulong_counter
, 0);
103 __this_cpu_add(ulong_counter
, ui_one
);
104 CHECK(ul
, ulong_counter
, 1);
107 __this_cpu_write(ulong_counter
, 0);
110 __this_cpu_sub(ulong_counter
, ui_one
);
111 CHECK(ul
, ulong_counter
, -1);
112 CHECK(ul
, ulong_counter
, ULONG_MAX
);
115 __this_cpu_write(ulong_counter
, 3);
117 ul
= this_cpu_sub_return(ulong_counter
, ui_one
);
118 CHECK(ul
, ulong_counter
, 2);
120 ul
= __this_cpu_sub_return(ulong_counter
, ui_one
);
121 CHECK(ul
, ulong_counter
, 1);
125 pr_info("percpu test done\n");
126 return -EAGAIN
; /* Fail will directly unload the module */
129 static void __exit
percpu_test_exit(void)
133 module_init(percpu_test_init
)
134 module_exit(percpu_test_exit
)
136 MODULE_LICENSE("GPL");
137 MODULE_AUTHOR("Greg Thelen");
138 MODULE_DESCRIPTION("percpu operations test");
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