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    SubjectRe: [PATCH v4 05/66] Maple Tree: Add new data structure
    Date
    * Vlastimil Babka <vbabka@suse.cz> [211215 07:54]:
    > On 12/1/21 15:29, Liam Howlett wrote:
    > > +/*
    > > + * mt_find() - Search from the start up until an entry is found.
    > > + * @mt: The maple tree
    > > + * @*index: Pointer which contains the start location of the search
    > > + * @max: The maximum value to check
    > > + *
    > > + * Handles locking.
    > > + *
    > > + * Return: The entry at or after the @*index or %NULL
    >
    > Noticed later that the comment doesn't say how *index is updated.

    Good point. I will add to the comment what happens to *index.

    >
    > > + */
    > > +void *mt_find(struct maple_tree *mt, unsigned long *index, unsigned long max)
    > > +{
    > > + MA_STATE(mas, mt, *index, *index);
    > > + void *entry;
    > > +#ifdef CONFIG_DEBUG_MAPLE_TREE
    > > + unsigned long copy = *index;
    > > +#endif
    > > +
    > > + trace_ma_read(__func__, &mas);
    > > +
    > > + if ((*index) > max)
    > > + return NULL;
    > > +
    > > + rcu_read_lock();
    > > +retry:
    > > + entry = mas_state_walk(&mas);
    > > + if (mas_is_start(&mas))
    > > + goto retry;
    > > +
    > > + if (unlikely(xa_is_zero(entry)))
    > > + entry = NULL;
    > > +
    > > + if (entry)
    > > + goto unlock;
    > > +
    > > + while (mas_searchable(&mas) && (mas.index < max)) {
    > > + entry = mas_next_entry(&mas, max);
    > > + if (likely(entry && !xa_is_zero(entry)))
    > > + break;
    > > + }
    > > +
    > > + if (unlikely(xa_is_zero(entry)))
    > > + entry = NULL;
    > > +unlock:
    > > + rcu_read_unlock();
    > > + if (likely(entry)) {
    > > + *index = mas.last + 1;
    > > +#ifdef CONFIG_DEBUG_MAPLE_TREE
    > > + if ((*index) && (*index) <= copy)
    > > + printk("index not increased! %lx <= %lx\n",
    > > + *index, copy);
    > > + MT_BUG_ON(mt, (*index) && ((*index) <= copy));
    > > +#endif
    > > + }
    > > +
    > > + return entry;
    > > +}
    > > +EXPORT_SYMBOL(mt_find);
    >
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