cregit-Linux how code gets into the kernel

Release 4.18 lib/percpu_test.c

Directory: lib
#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 */ }

Contributors

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Greg Thelen508100.00%1100.00%
Total508100.00%1100.00%


static void __exit percpu_test_exit(void) { }

Contributors

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Greg Thelen8100.00%1100.00%
Total8100.00%1100.00%

module_init(percpu_test_init) module_exit(percpu_test_exit) MODULE_LICENSE("GPL"); MODULE_AUTHOR("Greg Thelen"); MODULE_DESCRIPTION("percpu operations test");

Overall Contributors

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Greg Thelen571100.00%1100.00%
Total571100.00%1100.00%
Directory: lib
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