| Message ID | 20230603021558.95299-4-jhubbard@nvidia.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b764253c18821da31c49a260f92f5d093cf1637e |
| Headers | show |
| Series | A minor flurry of selftest/mm fixes | expand |
On 03.06.23 04:15, John Hubbard wrote: > The stop variable is a char*, and the code was assigning a char value to > it. This was generating a warning when compiling with clang. > > However, as both David and Peter pointed out, stop is not even used > after the problematic assignment to a char type. So just delete that > line entirely. > > Cc: David Hildenbrand <david@redhat.com> > Cc: Peter Xu <peterx@redhat.com> > Signed-off-by: John Hubbard <jhubbard@nvidia.com> > --- Reviewed-by: David Hildenbrand <david@redhat.com>
On Fri, Jun 02, 2023 at 07:15:50PM -0700, John Hubbard wrote: > The stop variable is a char*, and the code was assigning a char value to > it. This was generating a warning when compiling with clang. > > However, as both David and Peter pointed out, stop is not even used > after the problematic assignment to a char type. So just delete that > line entirely. > > Cc: David Hildenbrand <david@redhat.com> > Cc: Peter Xu <peterx@redhat.com> > Signed-off-by: John Hubbard <jhubbard@nvidia.com> > --- > tools/testing/selftests/mm/mlock2-tests.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/tools/testing/selftests/mm/mlock2-tests.c b/tools/testing/selftests/mm/mlock2-tests.c > index 11b2301f3aa3..80cddc0de206 100644 > --- a/tools/testing/selftests/mm/mlock2-tests.c > +++ b/tools/testing/selftests/mm/mlock2-tests.c > @@ -50,7 +50,6 @@ static int get_vm_area(unsigned long addr, struct vm_boundaries *area) > printf("cannot parse /proc/self/maps\n"); > goto out; > } > - stop = '\0'; > > sscanf(line, "%lx", &start); > sscanf(end_addr, "%lx", &end); I'd rather simply make it "*stop = '\0'", or as David suggested dropping stop completely when we're it (assumes that scanf() will always work with number ending with space ' '). No strong opinion here, though.
On 6/5/23 08:43, Peter Xu wrote: > On Fri, Jun 02, 2023 at 07:15:50PM -0700, John Hubbard wrote: >> The stop variable is a char*, and the code was assigning a char value to >> it. This was generating a warning when compiling with clang. >> >> However, as both David and Peter pointed out, stop is not even used >> after the problematic assignment to a char type. So just delete that >> line entirely. >> >> Cc: David Hildenbrand <david@redhat.com> >> Cc: Peter Xu <peterx@redhat.com> >> Signed-off-by: John Hubbard <jhubbard@nvidia.com> >> --- >> tools/testing/selftests/mm/mlock2-tests.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/tools/testing/selftests/mm/mlock2-tests.c b/tools/testing/selftests/mm/mlock2-tests.c >> index 11b2301f3aa3..80cddc0de206 100644 >> --- a/tools/testing/selftests/mm/mlock2-tests.c >> +++ b/tools/testing/selftests/mm/mlock2-tests.c >> @@ -50,7 +50,6 @@ static int get_vm_area(unsigned long addr, struct vm_boundaries *area) >> printf("cannot parse /proc/self/maps\n"); >> goto out; >> } >> - stop = '\0'; >> >> sscanf(line, "%lx", &start); >> sscanf(end_addr, "%lx", &end); > > I'd rather simply make it "*stop = '\0'", or as David suggested dropping > stop completely when we're it (assumes that scanf() will always work with > number ending with space ' '). Actually it does not assume that. Rather, it follows the documented behavior of strchr(3), which is: The strchr() and strrchr() functions return a pointer to the matched character or NULL if the character is not found. The terminating null byte is considered part of the string, so that if c is specified as '\0', these functions return a pointer to the terminator. And we have this code now: stop = strchr(end_addr, ' '); if (!stop) { printf("cannot parse /proc/self/maps\n"); goto out; } So, either stop has a valid char* in it, or we goto out. There are no fragile assumptions in there, as far as I can see anyway. > > No strong opinion here, though. > OK, I think it's kind of a flip of the coin whether to write this: stop = strchr(end_addr, ' '); if (!stop) { or this: if (!strchr(end_addr, ' ')) { So I'll just leave it as the first one, which (depending on the day of the week) might read slightly clearer. :) thanks,
diff --git a/tools/testing/selftests/mm/mlock2-tests.c b/tools/testing/selftests/mm/mlock2-tests.c index 11b2301f3aa3..80cddc0de206 100644 --- a/tools/testing/selftests/mm/mlock2-tests.c +++ b/tools/testing/selftests/mm/mlock2-tests.c @@ -50,7 +50,6 @@ static int get_vm_area(unsigned long addr, struct vm_boundaries *area) printf("cannot parse /proc/self/maps\n"); goto out; } - stop = '\0'; sscanf(line, "%lx", &start); sscanf(end_addr, "%lx", &end);
The stop variable is a char*, and the code was assigning a char value to it. This was generating a warning when compiling with clang. However, as both David and Peter pointed out, stop is not even used after the problematic assignment to a char type. So just delete that line entirely. Cc: David Hildenbrand <david@redhat.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- tools/testing/selftests/mm/mlock2-tests.c | 1 - 1 file changed, 1 deletion(-)