623fd8072c
Tests various percpu operations. Enable with CONFIG_PERCPU_TEST=m. Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
138 lines
3.2 KiB
C
138 lines
3.2 KiB
C
#include <linux/module.h>
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/* validate @native and @pcp counter values match @expected */
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#define CHECK(native, pcp, expected) \
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do { \
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WARN((native) != (expected), \
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"raw %ld (0x%lx) != expected %lld (0x%llx)", \
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(native), (native), \
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(long long)(expected), (long long)(expected)); \
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WARN(__this_cpu_read(pcp) != (expected), \
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"pcp %ld (0x%lx) != expected %lld (0x%llx)", \
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__this_cpu_read(pcp), __this_cpu_read(pcp), \
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(long long)(expected), (long long)(expected)); \
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} while (0)
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static DEFINE_PER_CPU(long, long_counter);
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static DEFINE_PER_CPU(unsigned long, ulong_counter);
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static int __init percpu_test_init(void)
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{
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/*
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* volatile prevents compiler from optimizing it uses, otherwise the
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* +ul_one/-ul_one below would replace with inc/dec instructions.
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*/
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volatile unsigned int ui_one = 1;
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long l = 0;
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unsigned long ul = 0;
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pr_info("percpu test start\n");
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preempt_disable();
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l += -1;
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__this_cpu_add(long_counter, -1);
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CHECK(l, long_counter, -1);
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l += 1;
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__this_cpu_add(long_counter, 1);
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CHECK(l, long_counter, 0);
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ul = 0;
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__this_cpu_write(ulong_counter, 0);
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ul += 1UL;
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__this_cpu_add(ulong_counter, 1UL);
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CHECK(ul, ulong_counter, 1);
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ul += -1UL;
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__this_cpu_add(ulong_counter, -1UL);
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CHECK(ul, ulong_counter, 0);
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ul += -(unsigned long)1;
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__this_cpu_add(ulong_counter, -(unsigned long)1);
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CHECK(ul, ulong_counter, -1);
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ul = 0;
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__this_cpu_write(ulong_counter, 0);
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ul -= 1;
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__this_cpu_dec(ulong_counter);
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CHECK(ul, ulong_counter, -1);
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CHECK(ul, ulong_counter, ULONG_MAX);
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l += -ui_one;
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__this_cpu_add(long_counter, -ui_one);
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CHECK(l, long_counter, 0xffffffff);
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l += ui_one;
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__this_cpu_add(long_counter, ui_one);
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CHECK(l, long_counter, (long)0x100000000LL);
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l = 0;
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__this_cpu_write(long_counter, 0);
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l -= ui_one;
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__this_cpu_sub(long_counter, ui_one);
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CHECK(l, long_counter, -1);
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l = 0;
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__this_cpu_write(long_counter, 0);
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l += ui_one;
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__this_cpu_add(long_counter, ui_one);
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CHECK(l, long_counter, 1);
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l += -ui_one;
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__this_cpu_add(long_counter, -ui_one);
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CHECK(l, long_counter, (long)0x100000000LL);
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l = 0;
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__this_cpu_write(long_counter, 0);
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l -= ui_one;
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this_cpu_sub(long_counter, ui_one);
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CHECK(l, long_counter, -1);
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CHECK(l, long_counter, ULONG_MAX);
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ul = 0;
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__this_cpu_write(ulong_counter, 0);
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ul += ui_one;
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__this_cpu_add(ulong_counter, ui_one);
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CHECK(ul, ulong_counter, 1);
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ul = 0;
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__this_cpu_write(ulong_counter, 0);
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ul -= ui_one;
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__this_cpu_sub(ulong_counter, ui_one);
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CHECK(ul, ulong_counter, -1);
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CHECK(ul, ulong_counter, ULONG_MAX);
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ul = 3;
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__this_cpu_write(ulong_counter, 3);
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ul = this_cpu_sub_return(ulong_counter, ui_one);
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CHECK(ul, ulong_counter, 2);
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ul = __this_cpu_sub_return(ulong_counter, ui_one);
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CHECK(ul, ulong_counter, 1);
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preempt_enable();
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pr_info("percpu test done\n");
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return -EAGAIN; /* Fail will directly unload the module */
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}
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static void __exit percpu_test_exit(void)
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{
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}
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module_init(percpu_test_init)
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module_exit(percpu_test_exit)
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Greg Thelen");
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MODULE_DESCRIPTION("percpu operations test");
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