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b=NHw7z6Jtm0S3j/LisGOhusIOB9ZWtoB7YVtGXxeqY83Gc6054WhFtvzuGmLL3ZTbe 5ngHxfyZ/FU9nu0R/x+AU+XXKLHfKDkUh1XsFGcB4EkXa6iKRVh6cE5Lcj+5yinfJt XL/HqBb2TkAhOIhpDiv1DBK+dVaZqKTweNqdg/jQ= Date: Mon, 22 Dec 2025 18:05:09 -0800 From: Andrew Morton To: Li Wang Cc: David Laight , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Mark Brown , Shuah Khan , Waiman Long Subject: Re: [PATCH v3 1/3] selftests/mm/write_to_hugetlbfs: parse -s as size_t Message-Id: <20251222180509.b12684e112195ac3f7ee9389@linux-foundation.org> In-Reply-To: References: <20251221122639.3168038-1-liwang@redhat.com> <20251221122639.3168038-2-liwang@redhat.com> <20251221221052.3b769fc2@pumpkin> <20251222094828.2783d9e5@pumpkin> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 87149C0003 X-Rspamd-Server: rspam10 X-Stat-Signature: 957oqermcwnsdm8dirans9q5fkwchcmh X-HE-Tag: 1766455511-215552 X-HE-Meta: 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 +GdJewiY 6xnQn6wnJXV21YLj0k/Am3p1O9mqlr/X/8YDa5Blybm2bJbvVKCaRKKjFbeMHSZhkr3xjm8kO1PF3SyIItLFQQq2uToAUNZiycgD5f/BYLixmjhsLHR1fk63UWJBBiY8kUlJLJmBIQcKuUsVCYRt6whRQvsPt9Cufr4cDwJLC4g43iY73ys/nWZhWMsuODwa9pxWz5G5ys2filK+lf4c7zthmQO0yMMvG28K9sIIdNEX91xo7zp0ztlKZ/6At57YqRdNNTZ+UZ3+tV42cJ769JeJ5aDVdxrn8Gn/WEfu6jC+qc45IMAmTJopmbEhMH1pK+U/LqO6bQ2EOhBkx5hXlv3g1DlBzqxTO82Lv X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 22 Dec 2025 18:56:49 +0800 Li Wang wrote: > > It reality scanf() is 'not the function you are lookign for'. > > > > IIRC the 'SUS' (used to) say that this was absolutely fine for command > > line parsing for 'standard utilities'. > > > > It is best to use strtoul() and check the 'end' character is '\0'. > > Hmm, that sounds like we need to go back to the patch V1 [1] method. > But I am not sure, @Andrew Morton, do you think so? > > --- a/tools/testing/selftests/mm/write_to_hugetlbfs.c > +++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c > @@ -86,10 +86,17 @@ int main(int argc, char **argv) > while ((c = getopt(argc, argv, "s:p:m:owlrn")) != -1) { > switch (c) { > case 's': > - if (sscanf(optarg, "%zu", &size) != 1) { > - perror("Invalid -s."); > + char *end = NULL; > + unsigned long tmp = strtoul(optarg, &end, 10); > + if (errno || end == optarg || *end != '\0') { > + perror("Invalid -s size"); > exit_usage(); > } > + if (tmp == 0) { > + perror("size not found"); > + exit_usage(); > + } > + size = (size_t)tmp; > break; > case 'p': Geeze guys, it's just a selftest. hp2:/usr/src/linux-6.19-rc1> grep -r scanf tools/testing/selftests | wc -l 177 if your command line breaks the selftest, fix your command line?