| Message ID | 20220718192844.1805158-3-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce DEBUG_BITMAP config option and bitmap_check_params() | expand |
On Mon, Jul 18, 2022 at 12:28:30PM -0700, Yury Norov wrote: > bitmap_parselist() format allows passing 0-length regions, but because > len == 0 is not covered by small_const_nbits() macro, we have to call > __bitmap_set() and do some prologue calculations just for nothing. ... > static void bitmap_set_region(const struct region *r, unsigned long *bitmap) > { > - unsigned int start; > + unsigned int start, len; > > - for (start = r->start; start <= r->end; start += r->group_len) > - bitmap_set(bitmap, start, min(r->end - start + 1, r->off)); > + for (start = r->start; start <= r->end; start += r->group_len) { > + len = min(r->end - start + 1, r->off); > + if (len > 0) > + bitmap_set(bitmap, start, len); Maybe I'm missing something, but how small_const_nbits() can possible be useful here? I mean in which cases the compiler would be able to prove that len is a const with < sizeof(unsigned long) bits? > + } > }
diff --git a/lib/bitmap.c b/lib/bitmap.c index cd4dd848ea6a..790df2ea02df 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -712,10 +712,13 @@ struct region { static void bitmap_set_region(const struct region *r, unsigned long *bitmap) { - unsigned int start; + unsigned int start, len; - for (start = r->start; start <= r->end; start += r->group_len) - bitmap_set(bitmap, start, min(r->end - start + 1, r->off)); + for (start = r->start; start <= r->end; start += r->group_len) { + len = min(r->end - start + 1, r->off); + if (len > 0) + bitmap_set(bitmap, start, len); + } } static int bitmap_check_region(const struct region *r)
bitmap_parselist() format allows passing 0-length regions, but because len == 0 is not covered by small_const_nbits() macro, we have to call __bitmap_set() and do some prologue calculations just for nothing. Signed-off-by: Yury Norov <yury.norov@gmail.com> --- lib/bitmap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)