On 2024/7/16 1:26, Bart Van Assche wrote:
On 7/15/24 2:11 AM, Yang Yang wrote:
+
+ /**
+ * @swap_lock: serializes simultaneous updates of ->word and ->cleared
+ */
+ spinlock_t swap_lock;
} ____cacheline_aligned_in_smp;
Thank you for having updated this comment.
-static inline bool sbitmap_deferred_clear(struct sbitmap_word *map)
+static inline bool sbitmap_deferred_clear(struct sbitmap_word *map,
+ unsigned int depth, unsigned int alloc_hint, bool wrap)
{
- unsigned long mask;
+ unsigned long mask, word_mask;
+ bool ret = false;
- if (!READ_ONCE(map->cleared))
- return false;
+ guard(spinlock_irqsave)(&map->swap_lock);
+
+ if (!map->cleared) {
+ if (depth > 0) {
+ word_mask = (~0UL) >> (BITS_PER_LONG - depth);
+ /*
+ * The current behavior is to always retry after moving
+ * ->cleared to word, and we change it to retry in case
+ * of any free bits. To avoid an infinite loop, we need
+ * to take wrap & alloc_hint into account, otherwise a
+ * soft lockup may occur.
+ */
+ if (!wrap && alloc_hint)
+ word_mask &= ~((1UL << alloc_hint) - 1);
+
+ if ((READ_ONCE(map->word) & word_mask) == word_mask)
+ ret = false;
+ else
+ ret = true;
+ }
+
+ return ret;
+ }
Now that guard()() is being used, the local variable 'ret' can be eliminated. The if
(READ_ONCE() ...) statement can be changed into the
following: return (READ_ONCE(map->word) & word_mask) != word_mask;
and "return ret;" can be changed into "return false;". Additionally,
the indentation depth can be reduced by changing "if (depth > 0) {" ...
into "if (depth == 0) return false;".
This looks much better, I will make these changes in the next version.
Thanks.
Otherwise this patch looks good to me.
Thanks,
Bart.
