1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | #include <linux/module.h> |
3 | |
4 | /* validate @native and @pcp counter values match @expected */ |
5 | #define CHECK(native, pcp, expected) \ |
6 | do { \ |
7 | WARN((native) != (expected), \ |
8 | "raw %ld (0x%lx) != expected %lld (0x%llx)", \ |
9 | (native), (native), \ |
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)); \ |
15 | } while (0) |
16 | |
17 | static DEFINE_PER_CPU(long, long_counter); |
18 | static DEFINE_PER_CPU(unsigned long, ulong_counter); |
19 | |
20 | static int __init percpu_test_init(void) |
21 | { |
22 | /* |
23 | * volatile prevents compiler from optimizing it uses, otherwise the |
24 | * +ul_one/-ul_one below would replace with inc/dec instructions. |
25 | */ |
26 | volatile unsigned int ui_one = 1; |
27 | long l = 0; |
28 | unsigned long ul = 0; |
29 | |
30 | pr_info("percpu test start\n" ); |
31 | |
32 | preempt_disable(); |
33 | |
34 | l += -1; |
35 | __this_cpu_add(long_counter, -1); |
36 | CHECK(l, long_counter, -1); |
37 | |
38 | l += 1; |
39 | __this_cpu_add(long_counter, 1); |
40 | CHECK(l, long_counter, 0); |
41 | |
42 | ul = 0; |
43 | __this_cpu_write(ulong_counter, 0); |
44 | |
45 | ul += 1UL; |
46 | __this_cpu_add(ulong_counter, 1UL); |
47 | CHECK(ul, ulong_counter, 1); |
48 | |
49 | ul += -1UL; |
50 | __this_cpu_add(ulong_counter, -1UL); |
51 | CHECK(ul, ulong_counter, 0); |
52 | |
53 | ul += -(unsigned long)1; |
54 | __this_cpu_add(ulong_counter, -(unsigned long)1); |
55 | CHECK(ul, ulong_counter, -1); |
56 | |
57 | ul = 0; |
58 | __this_cpu_write(ulong_counter, 0); |
59 | |
60 | ul -= 1; |
61 | __this_cpu_dec(ulong_counter); |
62 | CHECK(ul, ulong_counter, -1); |
63 | CHECK(ul, ulong_counter, ULONG_MAX); |
64 | |
65 | l += -ui_one; |
66 | __this_cpu_add(long_counter, -ui_one); |
67 | CHECK(l, long_counter, 0xffffffff); |
68 | |
69 | l += ui_one; |
70 | __this_cpu_add(long_counter, ui_one); |
71 | CHECK(l, long_counter, (long)0x100000000LL); |
72 | |
73 | |
74 | l = 0; |
75 | __this_cpu_write(long_counter, 0); |
76 | |
77 | l -= ui_one; |
78 | __this_cpu_sub(long_counter, ui_one); |
79 | CHECK(l, long_counter, -1); |
80 | |
81 | l = 0; |
82 | __this_cpu_write(long_counter, 0); |
83 | |
84 | l += ui_one; |
85 | __this_cpu_add(long_counter, ui_one); |
86 | CHECK(l, long_counter, 1); |
87 | |
88 | l += -ui_one; |
89 | __this_cpu_add(long_counter, -ui_one); |
90 | CHECK(l, long_counter, (long)0x100000000LL); |
91 | |
92 | l = 0; |
93 | __this_cpu_write(long_counter, 0); |
94 | |
95 | l -= ui_one; |
96 | this_cpu_sub(long_counter, ui_one); |
97 | CHECK(l, long_counter, -1); |
98 | CHECK(l, long_counter, ULONG_MAX); |
99 | |
100 | ul = 0; |
101 | __this_cpu_write(ulong_counter, 0); |
102 | |
103 | ul += ui_one; |
104 | __this_cpu_add(ulong_counter, ui_one); |
105 | CHECK(ul, ulong_counter, 1); |
106 | |
107 | ul = 0; |
108 | __this_cpu_write(ulong_counter, 0); |
109 | |
110 | ul -= ui_one; |
111 | __this_cpu_sub(ulong_counter, ui_one); |
112 | CHECK(ul, ulong_counter, -1); |
113 | CHECK(ul, ulong_counter, ULONG_MAX); |
114 | |
115 | ul = 3; |
116 | __this_cpu_write(ulong_counter, 3); |
117 | |
118 | ul = this_cpu_sub_return(ulong_counter, ui_one); |
119 | CHECK(ul, ulong_counter, 2); |
120 | |
121 | ul = __this_cpu_sub_return(ulong_counter, ui_one); |
122 | CHECK(ul, ulong_counter, 1); |
123 | |
124 | preempt_enable(); |
125 | |
126 | pr_info("percpu test done\n" ); |
127 | return -EAGAIN; /* Fail will directly unload the module */ |
128 | } |
129 | |
130 | static void __exit percpu_test_exit(void) |
131 | { |
132 | } |
133 | |
134 | module_init(percpu_test_init) |
135 | module_exit(percpu_test_exit) |
136 | |
137 | MODULE_LICENSE("GPL" ); |
138 | MODULE_AUTHOR("Greg Thelen" ); |
139 | MODULE_DESCRIPTION("percpu operations test" ); |
140 | |