1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
4 /* validate @native and @pcp counter values match @expected */
5 #define CHECK(native, pcp, expected) \
7 WARN((native) != (expected), \
8 "raw %ld (0x%lx) != expected %lld (0x%llx)", \
10 (long long)(expected), (long long)(expected)); \
11 WARN(__this_cpu_read(pcp) != (expected), \
12 "pcp %ld (0x%lx) != expected %lld (0x%llx)", \
13 __this_cpu_read(pcp), __this_cpu_read(pcp), \
14 (long long)(expected), (long long)(expected)); \
17 static DEFINE_PER_CPU(long, long_counter);
18 static DEFINE_PER_CPU(unsigned long, ulong_counter);
20 static int __init percpu_test_init(void)
23 * volatile prevents compiler from optimizing it uses, otherwise the
24 * +ul_one/-ul_one below would replace with inc/dec instructions.
26 volatile unsigned int ui_one = 1;
30 pr_info("percpu test start\n");
35 __this_cpu_add(long_counter, -1);
36 CHECK(l, long_counter, -1);
39 __this_cpu_add(long_counter, 1);
40 CHECK(l, long_counter, 0);
43 __this_cpu_write(ulong_counter, 0);
46 __this_cpu_add(ulong_counter, 1UL);
47 CHECK(ul, ulong_counter, 1);
50 __this_cpu_add(ulong_counter, -1UL);
51 CHECK(ul, ulong_counter, 0);
53 ul += -(unsigned long)1;
54 __this_cpu_add(ulong_counter, -(unsigned long)1);
55 CHECK(ul, ulong_counter, -1);
58 __this_cpu_write(ulong_counter, 0);
61 __this_cpu_dec(ulong_counter);
62 CHECK(ul, ulong_counter, -1);
63 CHECK(ul, ulong_counter, ULONG_MAX);
66 __this_cpu_add(long_counter, -ui_one);
67 CHECK(l, long_counter, 0xffffffff);
70 __this_cpu_add(long_counter, ui_one);
71 CHECK(l, long_counter, (long)0x100000000LL);
75 __this_cpu_write(long_counter, 0);
78 __this_cpu_sub(long_counter, ui_one);
79 CHECK(l, long_counter, -1);
82 __this_cpu_write(long_counter, 0);
85 __this_cpu_add(long_counter, ui_one);
86 CHECK(l, long_counter, 1);
89 __this_cpu_add(long_counter, -ui_one);
90 CHECK(l, long_counter, (long)0x100000000LL);
93 __this_cpu_write(long_counter, 0);
96 this_cpu_sub(long_counter, ui_one);
97 CHECK(l, long_counter, -1);
98 CHECK(l, long_counter, ULONG_MAX);
101 __this_cpu_write(ulong_counter, 0);
104 __this_cpu_add(ulong_counter, ui_one);
105 CHECK(ul, ulong_counter, 1);
108 __this_cpu_write(ulong_counter, 0);
111 __this_cpu_sub(ulong_counter, ui_one);
112 CHECK(ul, ulong_counter, -1);
113 CHECK(ul, ulong_counter, ULONG_MAX);
116 __this_cpu_write(ulong_counter, 3);
118 ul = this_cpu_sub_return(ulong_counter, ui_one);
119 CHECK(ul, ulong_counter, 2);
121 ul = __this_cpu_sub_return(ulong_counter, ui_one);
122 CHECK(ul, ulong_counter, 1);
126 pr_info("percpu test done\n");
127 return -EAGAIN; /* Fail will directly unload the module */
130 static void __exit percpu_test_exit(void)
134 module_init(percpu_test_init)
135 module_exit(percpu_test_exit)
137 MODULE_LICENSE("GPL");
138 MODULE_AUTHOR("Greg Thelen");
139 MODULE_DESCRIPTION("percpu operations test");