linux-kernel - Re: [PATCH v3 7/7] selftests/resctrl: Cleanup benchmark argument parsing

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Date:   Tue, 29 Aug 2023 16:04:29 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Maciej Wieczór-Retman 
        <maciej.wieczor-retman@...el.com>
cc:     Reinette Chatre <reinette.chatre@...el.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-kselftest@...r.kernel.org, Shuah Khan <shuah@...nel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Babu Moger <babu.moger@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH v3 7/7] selftests/resctrl: Cleanup benchmark argument
 parsing

On Tue, 29 Aug 2023, Maciej Wieczór-Retman wrote:
> On 2023-08-23 at 16:15:56 +0300, Ilpo Järvinen wrote:
> >Benchmark argument is handled by custom argument parsing code which is
> >more complicated than it needs to be.
> >
> >Process benchmark argument within the normal getopt() handling and drop
> >entirely unnecessary ben_ind and has_ben variables. If -b is not given,
> >setup the default benchmark command right after the switch statement
> >and make -b to goto over it while it terminates the getopt() loop.
> >
> >Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> >Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
> >---
> > .../testing/selftests/resctrl/resctrl_tests.c | 71 ++++++++++---------
> > 1 file changed, 36 insertions(+), 35 deletions(-)
> >
> >diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
> >index 94516d1f4307..ae9001ef7b0a 100644
> >--- a/tools/testing/selftests/resctrl/resctrl_tests.c
> >+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> >@@ -169,28 +169,35 @@ static void run_cat_test(int cpu_no, int no_of_bits)
> > 
> > int main(int argc, char **argv)
> > {
> >-	bool has_ben = false, mbm_test = true, mba_test = true, cmt_test = true;
> >-	int c, cpu_no = 1, argc_new = argc, i, no_of_bits = 0;
> >+	bool mbm_test = true, mba_test = true, cmt_test = true;
> >+	int c, cpu_no = 1, i, no_of_bits = 0;
> > 	const char *benchmark_cmd[BENCHMARK_ARGS];
> >-	int ben_ind, tests = 0;
> > 	char *span_str = NULL;
> > 	bool cat_test = true;
> > 	char *skip_reason;
> >+	int tests = 0;
> > 	int ret;
> > 
> >-	for (i = 0; i < argc; i++) {
> >-		if (strcmp(argv[i], "-b") == 0) {
> >-			ben_ind = i + 1;
> >-			argc_new = ben_ind - 1;
> >-			has_ben = true;
> >-			break;
> >-		}
> >-	}
> >-
> >-	while ((c = getopt(argc_new, argv, "ht:b:n:p:")) != -1) {
> >+	while ((c = getopt(argc, argv, "ht:b:n:p:")) != -1) {
> > 		char *token;
> > 
> > 		switch (c) {
> >+		case 'b':
> >+			/*
> >+			 * First move optind back to the (first) optarg and
> >+			 * then build the benchmark command using the
> >+			 * remaining arguments.
> >+			 */
> >+			optind--;
> >+			if (argc - optind >= BENCHMARK_ARGS - 1)
> >+				ksft_exit_fail_msg("Too long benchmark command");
> 
> Isn't this condition off by two?
> 
> I did some testing and the maximum amount of benchmark arguments is 62
> while the array of const char* has 64 spaces. Is it supposed to have
> less than the maximum capacity?
> 
> Wouldn't something like this be more valid with BENCHMARK_ARGS equal to
> 64? :
> 			if (argc - optind > BENCHMARK_ARGS)

Certainly not off by two as the array must be NULL terminated but it seems 
to be off-by-one (to the safe direction), yes.

-- 
 i.