On Tue, 23 Dec 2025 10:41:22 +0800 Li Wang <[email protected]> wrote:
> Andrew Morton <[email protected]> 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 >
