From 4a7bba1df00163ecbdf4994bc42b879ade4aeed2 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Wed, 16 Oct 2024 21:23:52 +0300 Subject: [PATCH] percpu: add a test case for the specific 64-bit value addition 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 Cc: Borislav Petkov (AMD) Cc: Christoph Lameter Cc: Dave Hansen Cc: Dennis Zhou Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Ingo Molnar Cc: Tejun Heo Cc: Thomas Gleixner Cc: Uros Bizjak Signed-off-by: Andrew Morton --- lib/percpu_test.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/lib/percpu_test.c b/lib/percpu_test.c index 4a3d70bbc1a0..ce7124b16dab 100644 --- a/lib/percpu_test.c +++ b/lib/percpu_test.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-only +#include #include /* validate @native and @pcp counter values match @expected */ @@ -24,8 +25,9 @@ static int __init percpu_test_init(void) * +ul_one/-ul_one below would replace with inc/dec instructions. */ volatile unsigned int ui_one = 1; - long l = 0; + unsigned long long ull = 0; unsigned long ul = 0; + long l = 0; pr_info("percpu test start\n"); @@ -112,6 +114,13 @@ static int __init percpu_test_init(void) CHECK(ul, ulong_counter, -1); CHECK(ul, ulong_counter, ULONG_MAX); + ul = ull = 0; + __this_cpu_write(ulong_counter, 0); + + ul = ull += UINT_MAX; + __this_cpu_add(ulong_counter, ull); + CHECK(ul, ulong_counter, UINT_MAX); + ul = 3; __this_cpu_write(ulong_counter, 3);