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- #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");
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