On Tue, 23 Dec 2025 10:41:22 +0800 Li Wang liwang@redhat.com wrote:
Andrew Morton akpm@linux-foundation.org wrote:
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;
Initialiser not needed.
unsigned long tmp = strtoul(optarg, &end, 10);if (errno || end == optarg || *end != '\0') {
I doubt that use of errno is correct. Library functions that set errno on error don't set it to zero. The only test needed there is *end != ''. (end == optarg will be picked up by size == 0 later - if that is actually needed to stop things breaking.)
perror("Invalid -s size"); exit_usage(); }if (tmp == 0) {
No point checking for zero before the assigning the 'unsigned long' to 'size_t'. So the result of strtoul() can just be just assigned to 'size'. (Ignoring the fact that size_t will be unsigned long.)
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?
Yes, I am ok with sscanf() :-).
What was wrong with atoi() ? Or, at most, strtoul() with a check that *end == 0.
David
In fact, write_to hugetlbfs currently only accepts arguments from charge_reserved_hugetlb.sh, and the way the '-s' is used is not very diverse.
-- Regards, Li Wang