Re: [PATCH v3 05/19] perf test: Add deterministic workload

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Signed integer overflow in 'dt_work' multiplications.
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commit 89c17c87c140a5545531995cc6d206a8c6fffd71
Author: James Clark <james.clark@linaro.org>

perf test: Add deterministic workload

This commit adds a deterministic workload to the perf test suite for testing
CPU trace decoding. It introduces a new test file that performs repeated
multiplications on a global variable to ensure a predictable execution path.

> diff --git a/tools/perf/tests/workloads/deterministic.c b/tools/perf/tests/workloads/deterministic.c
> new file mode 100644
> index 0000000000000..3caea8564043c
> --- /dev/null
> +++ b/tools/perf/tests/workloads/deterministic.c
> @@ -0,0 +1,39 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/compiler.h>
> +#include "../tests.h"
> +
> +int dt_work = 1234;

[Severity: Medium]
Will this signed integer overflow during the repeated multiplications?

Since dt_work is a 32-bit signed integer initialized to 1234 and is multiplied
by 7 repeatedly across deterministic(), function1(), and function2(), the 8th
multiplication operation attempts to evaluate to 7,113,764,434.

This exceeds the maximum signed 32-bit integer limit of 2,147,483,647 and
triggers undefined behavior in C.

Could dt_work be declared as an unsigned int instead? If the perf tools are
compiled with Undefined Behavior Sanitizer enabled, this signed integer
overflow will cause the test workload to crash.

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260603-james-cs-context-tracking-fix-v3-0-c392945d9ed5@linaro.org?part=5