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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-01-12 23:54:10 +0300
committerMatthew Wilcox (Oracle) <willy@infradead.org>2020-01-18 06:33:37 +0300
commit00ed452c210a0bc1ff3ee79e1ce6b199f00a0638 (patch)
tree519e830435204683e32c9ded6ff4e7d4778f3922 /include
parentc44aa5e8ab58b5f4cf473970ec784c3333496a2e (diff)
downloadlinux-00ed452c210a0bc1ff3ee79e1ce6b199f00a0638.tar.xz
XArray: Add xa_for_each_range
This function supports iterating over a range of an array. Also add documentation links for xa_for_each_start(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/xarray.h37
1 files changed, 32 insertions, 5 deletions
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 736afd3aa56f..f73e1775ded0 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -417,6 +417,36 @@ static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
}
/**
+ * xa_for_each_range() - Iterate over a portion of an XArray.
+ * @xa: XArray.
+ * @index: Index of @entry.
+ * @entry: Entry retrieved from array.
+ * @start: First index to retrieve from array.
+ * @last: Last index to retrieve from array.
+ *
+ * During the iteration, @entry will have the value of the entry stored
+ * in @xa at @index. You may modify @index during the iteration if you
+ * want to skip or reprocess indices. It is safe to modify the array
+ * during the iteration. At the end of the iteration, @entry will be set
+ * to NULL and @index will have a value less than or equal to max.
+ *
+ * xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n). You have
+ * to handle your own locking with xas_for_each(), and if you have to unlock
+ * after each iteration, it will also end up being O(n.log(n)).
+ * xa_for_each_range() will spin if it hits a retry entry; if you intend to
+ * see retry entries, you should use the xas_for_each() iterator instead.
+ * The xas_for_each() iterator will expand into more inline code than
+ * xa_for_each_range().
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ */
+#define xa_for_each_range(xa, index, entry, start, last) \
+ for (index = start, \
+ entry = xa_find(xa, &index, last, XA_PRESENT); \
+ entry; \
+ entry = xa_find_after(xa, &index, last, XA_PRESENT))
+
+/**
* xa_for_each_start() - Iterate over a portion of an XArray.
* @xa: XArray.
* @index: Index of @entry.
@@ -439,11 +469,8 @@ static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
*
* Context: Any context. Takes and releases the RCU lock.
*/
-#define xa_for_each_start(xa, index, entry, start) \
- for (index = start, \
- entry = xa_find(xa, &index, ULONG_MAX, XA_PRESENT); \
- entry; \
- entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT))
+#define xa_for_each_start(xa, index, entry, start) \
+ xa_for_each_range(xa, index, entry, start, ULONG_MAX)
/**
* xa_for_each() - Iterate over present entries in an XArray.