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It might be a corner case when we add UINT_MAX as 64-bit unsigned value to the percpu variable as it's not the same as -1 (ULONG_LONG_MAX). Add a test case for that. Link: https://lkml.kernel.org/r/20241016182635.1156168-3-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Christoph Lameter <cl@linux.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Uros Bizjak <ubizjak@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
148 lines
3.4 KiB
C
148 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/limits.h>
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#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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unsigned long long ull = 0;
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unsigned long ul = 0;
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long l = 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 = ull = 0;
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__this_cpu_write(ulong_counter, 0);
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ul = ull += UINT_MAX;
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__this_cpu_add(ulong_counter, ull);
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CHECK(ul, ulong_counter, UINT_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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