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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 | // SPDX-License-Identifier: GPL-2.0-only #include <linux/module.h> /* validate @native and @pcp counter values match @expected */ #define CHECK(native, pcp, expected) \ do { \ WARN((native) != (expected), \ "raw %ld (0x%lx) != expected %lld (0x%llx)", \ (native), (native), \ (long long)(expected), (long long)(expected)); \ WARN(__this_cpu_read(pcp) != (expected), \ "pcp %ld (0x%lx) != expected %lld (0x%llx)", \ __this_cpu_read(pcp), __this_cpu_read(pcp), \ (long long)(expected), (long long)(expected)); \ } while (0) static DEFINE_PER_CPU(long, long_counter); static DEFINE_PER_CPU(unsigned long, ulong_counter); static int __init percpu_test_init(void) { /* * volatile prevents compiler from optimizing it uses, otherwise the * +ul_one/-ul_one below would replace with inc/dec instructions. */ volatile unsigned int ui_one = 1; long l = 0; unsigned long ul = 0; pr_info("percpu test start\n"); preempt_disable(); l += -1; __this_cpu_add(long_counter, -1); CHECK(l, long_counter, -1); l += 1; __this_cpu_add(long_counter, 1); CHECK(l, long_counter, 0); ul = 0; __this_cpu_write(ulong_counter, 0); ul += 1UL; __this_cpu_add(ulong_counter, 1UL); CHECK(ul, ulong_counter, 1); ul += -1UL; __this_cpu_add(ulong_counter, -1UL); CHECK(ul, ulong_counter, 0); ul += -(unsigned long)1; __this_cpu_add(ulong_counter, -(unsigned long)1); CHECK(ul, ulong_counter, -1); ul = 0; __this_cpu_write(ulong_counter, 0); ul -= 1; __this_cpu_dec(ulong_counter); CHECK(ul, ulong_counter, -1); CHECK(ul, ulong_counter, ULONG_MAX); l += -ui_one; __this_cpu_add(long_counter, -ui_one); CHECK(l, long_counter, 0xffffffff); l += ui_one; __this_cpu_add(long_counter, ui_one); CHECK(l, long_counter, (long)0x100000000LL); l = 0; __this_cpu_write(long_counter, 0); l -= ui_one; __this_cpu_sub(long_counter, ui_one); CHECK(l, long_counter, -1); l = 0; __this_cpu_write(long_counter, 0); l += ui_one; __this_cpu_add(long_counter, ui_one); CHECK(l, long_counter, 1); l += -ui_one; __this_cpu_add(long_counter, -ui_one); CHECK(l, long_counter, (long)0x100000000LL); l = 0; __this_cpu_write(long_counter, 0); l -= ui_one; this_cpu_sub(long_counter, ui_one); CHECK(l, long_counter, -1); CHECK(l, long_counter, ULONG_MAX); ul = 0; __this_cpu_write(ulong_counter, 0); ul += ui_one; __this_cpu_add(ulong_counter, ui_one); CHECK(ul, ulong_counter, 1); ul = 0; __this_cpu_write(ulong_counter, 0); ul -= ui_one; __this_cpu_sub(ulong_counter, ui_one); CHECK(ul, ulong_counter, -1); CHECK(ul, ulong_counter, ULONG_MAX); ul = 3; __this_cpu_write(ulong_counter, 3); ul = this_cpu_sub_return(ulong_counter, ui_one); CHECK(ul, ulong_counter, 2); ul = __this_cpu_sub_return(ulong_counter, ui_one); CHECK(ul, ulong_counter, 1); preempt_enable(); pr_info("percpu test done\n"); return -EAGAIN; /* Fail will directly unload the module */ } static void __exit percpu_test_exit(void) { } module_init(percpu_test_init) module_exit(percpu_test_exit) MODULE_LICENSE("GPL"); MODULE_AUTHOR("Greg Thelen"); MODULE_DESCRIPTION("percpu operations test"); |