xarray: Extract entries from an XArray (80a0a1a9) · Commits · 戴 / test

include/linux/xarray.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -284,6 +284,8 @@ void xa_find(struct xarray xa, unsigned long *index,
		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
		void xa_find_after(struct xarray xa, unsigned long *index,
		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
		unsigned int xa_extract(struct xarray , void *dst, unsigned long start,
		unsigned long max, unsigned int n, xa_mark_t);

		/**
		* xa_init() - Initialise an empty XArray.

lib/xarray.c

+80 −0

Original line number	Diff line number	Diff line
		@@ -1444,6 +1444,86 @@ void xa_find_after(struct xarray xa, unsigned long *indexp,
		}
		EXPORT_SYMBOL(xa_find_after);

		static unsigned int xas_extract_present(struct xa_state xas, void *dst,
		unsigned long max, unsigned int n)
		{
		void *entry;
		unsigned int i = 0;

		rcu_read_lock();
		xas_for_each(xas, entry, max) {
		if (xas_retry(xas, entry))
		continue;
		dst[i++] = entry;
		if (i == n)
		break;
		}
		rcu_read_unlock();

		return i;
		}

		static unsigned int xas_extract_marked(struct xa_state xas, void *dst,
		unsigned long max, unsigned int n, xa_mark_t mark)
		{
		void *entry;
		unsigned int i = 0;

		rcu_read_lock();
		xas_for_each_marked(xas, entry, max, mark) {
		if (xas_retry(xas, entry))
		continue;
		dst[i++] = entry;
		if (i == n)
		break;
		}
		rcu_read_unlock();

		return i;
		}

		/**
		* xa_extract() - Copy selected entries from the XArray into a normal array.
		* @xa: The source XArray to copy from.
		* @dst: The buffer to copy entries into.
		* @start: The first index in the XArray eligible to be selected.
		* @max: The last index in the XArray eligible to be selected.
		* @n: The maximum number of entries to copy.
		* @filter: Selection criterion.
		*
		* Copies up to @n entries that match @filter from the XArray. The
		* copied entries will have indices between @start and @max, inclusive.
		*
		* The @filter may be an XArray mark value, in which case entries which are
		* marked with that mark will be copied. It may also be %XA_PRESENT, in
		* which case all entries which are not NULL will be copied.
		*
		* The entries returned may not represent a snapshot of the XArray at a
		* moment in time. For example, if another thread stores to index 5, then
		* index 10, calling xa_extract() may return the old contents of index 5
		* and the new contents of index 10. Indices not modified while this
		* function is running will not be skipped.
		*
		* If you need stronger guarantees, holding the xa_lock across calls to this
		* function will prevent concurrent modification.
		*
		* Context: Any context. Takes and releases the RCU lock.
		* Return: The number of entries copied.
		*/
		unsigned int xa_extract(struct xarray xa, void *dst, unsigned long start,
		unsigned long max, unsigned int n, xa_mark_t filter)
		{
		XA_STATE(xas, xa, start);

		if (!n)
		return 0;

		if ((__force unsigned int)filter < XA_MAX_MARKS)
		return xas_extract_marked(&xas, dst, max, n, filter);
		return xas_extract_present(&xas, dst, max, n);
		}
		EXPORT_SYMBOL(xa_extract);

		#ifdef XA_DEBUG
		void xa_dump_node(const struct xa_node *node)
		{

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