Re: [PATCH 08/15] perf test: Show snippet failure output for verbose=1

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] O(N^2) time complexity in `find_next_keyword` when processing long lines.
--

commit 2095066ea9915f694a9267e1143ad972e358c87f
Author: Ian Rogers <irogers@google.com>

perf test: Show snippet failure output for verbose=1

This patch introduces a smart failure snippet processor for perf tests running
in verbose mode. It dynamically parses the raw error buffer to extract up to a
configurable number of lines containing failure keywords, highlighting them in
red. This prevents massive log dumps from hiding important diagnostic keywords.

> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c

[ ... ]

> @@ -400,6 +402,192 @@ static int print_test_result(struct test_suite *t, int curr_suite, int curr_test
>  	return 0;
>  }
>  
> +static const char * const fail_keywords[] = {
> +	"error", "fail", "segv", "abort",
> +	"signal", "fatal", "panic", "corrupt", NULL
> +};
> +
> +static const char *find_next_keyword(const char *str, size_t max_len, size_t *kw_len)
> +{
> +	const char *best = NULL;
> +	size_t best_len = 0;
> +	int k;
> +
> +	for (k = 0; fail_keywords[k]; k++) {
> +		const char *s = str;
> +		size_t len = strlen(fail_keywords[k]);
> +
> +		while ((size_t)(s - str) + len <= max_len) {

[Severity: Medium]
The find_next_keyword function searches for multiple keywords independently.
If an earlier keyword match (best) has already been found, this loop continues
scanning the remainder of the string for the other keywords up to max_len.

Could this loop be optimized to stop when the search pointer passes the best
match so far?

> +			size_t i;
> +
> +			for (i = 0; i < len; i++) {
> +				if (tolower(s[i]) != fail_keywords[k][i])
> +					break;
> +			}

[ ... ]

> +static void print_line_highlighted(FILE *fp, const char *line, size_t len)
> +{
> +	const char *s = line;
> +
> +	while (len > 0) {
> +		size_t kw_len = 0;
> +		const char *match = find_next_keyword(s, len, &kw_len);

[Severity: Medium]
Since print_line_highlighted repeatedly invokes find_next_keyword after each
match, and find_next_keyword scans the entire remaining max_len for every
missing keyword, a line with many occurrences of one keyword (e.g., error)
but lacking others could cause repeated full-length scans.

Can this lead to excessive processing time and quadratic behavior for very
long lines?

> +
> +		if (!match) {
> +			fwrite(s, 1, len, fp);
> +			break;
> +		}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260601061401.1541457-1-irogers@google.com?part=8