Le 03/12/2021 à 22:04, Boris Ostrovsky a écrit :
On 12/3/21 10:54 AM, Christophe JAILLET wrote:
Le 03/12/2021 à 04:03, Joe Perches a écrit :
I get your point now, and I agree with you.
Maybe something as what is done in mc-entity.c?
Explicitly require more bits (which will be allocated anyway), instead
of taking advantage (read "hoping") that it will be done.
Could be:
@@ -440,26 +440,25 @@ static int xlbd_reserve_minors(unsigned int
minor, unsigned int nr)
int rc;
if (end > nr_minors) {
unsigned long *bitmap, *old;
- bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
- GFP_KERNEL);
+ end = ALIGN(end, BITS_PER_LONG);
+ bitmap = bitmap_zalloc(end, GFP_KERNEL);
if (bitmap == NULL)
return -ENOMEM;
spin_lock(&minor_lock);
if (end > nr_minors) {
old = minors;
- memcpy(bitmap, minors,
- BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
+ bitmap_copy(bitmap, minors, nr_minors);
minors = bitmap;
- nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
+ nr_minors = end;
} else
old = bitmap;
spin_unlock(&minor_lock);
- kfree(old);
+ bitmap_free(old);
}
spin_lock(&minor_lock);
if (find_next_bit(minors, end, minor) >= end) {
I don't think this will work anymore, we may now fail if another thread
gets a minor above the original (i.e. no aligned) @end.
So, maybe adding an "official" 'bitmap_size()' (which is already
existing and duplicated in a few places) would ease things.
It would replace the 'nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;'
and hide the implementation details of the bitmap API.
Something like:
static __always_inline size_t bitmap_size(unsigned long nr_bits)
{
return BITS_TO_LONGS(nr_bits) * sizeof(long);
}
CJ
-boris
