xarray: Destroy an XArray

This function frees all the internal memory allocated to the xarray
and reinitialises it to be empty.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 82ceed9819245de8f268a8d4afb6a2f9d17515de..0a758fa3ed2c783ebe86cd7a8bc58af49feafde2 100644 (file)
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -286,6 +286,7 @@ 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);
+void xa_destroy(struct xarray *);
 
 /**
  * xa_init() - Initialise an empty XArray.

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index e3c2d4d00b15cc9421e19139a94563c7a78b6558..a96f67caa1c2e94d95c86c4809e38a8904834246 100644 (file)
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -465,6 +465,39 @@ static noinline void check_find(struct xarray *xa)
        check_multi_find_2(xa);
 }
 
+static noinline void check_destroy(struct xarray *xa)
+{
+       unsigned long index;
+
+       XA_BUG_ON(xa, !xa_empty(xa));
+
+       /* Destroying an empty array is a no-op */
+       xa_destroy(xa);
+       XA_BUG_ON(xa, !xa_empty(xa));
+
+       /* Destroying an array with a single entry */
+       for (index = 0; index < 1000; index++) {
+               xa_store_index(xa, index, GFP_KERNEL);
+               XA_BUG_ON(xa, xa_empty(xa));
+               xa_destroy(xa);
+               XA_BUG_ON(xa, !xa_empty(xa));
+       }
+
+       /* Destroying an array with a single entry at ULONG_MAX */
+       xa_store(xa, ULONG_MAX, xa, GFP_KERNEL);
+       XA_BUG_ON(xa, xa_empty(xa));
+       xa_destroy(xa);
+       XA_BUG_ON(xa, !xa_empty(xa));
+
+#ifdef CONFIG_XARRAY_MULTI
+       /* Destroying an array with a multi-index entry */
+       xa_store_order(xa, 1 << 11, 11, xa, GFP_KERNEL);
+       XA_BUG_ON(xa, xa_empty(xa));
+       xa_destroy(xa);
+       XA_BUG_ON(xa, !xa_empty(xa));
+#endif
+}
+
 static DEFINE_XARRAY(array);
 
 static int xarray_checks(void)
@@ -478,6 +511,7 @@ static int xarray_checks(void)
        check_cmpxchg(&array);
        check_multi_store(&array);
        check_find(&array);
+       check_destroy(&array);
 
        printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
        return (tests_run == tests_passed) ? 0 : -EINVAL;

diff --git a/lib/xarray.c b/lib/xarray.c
index 70e04810c8c26c5610200dc5b26e0021041cc3a6..057dbe0d3bf61ed18b9e1cc019f4e61e3fcc51ef 100644 (file)
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1524,6 +1524,34 @@ unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
 }
 EXPORT_SYMBOL(xa_extract);
 
+/**
+ * xa_destroy() - Free all internal data structures.
+ * @xa: XArray.
+ *
+ * After calling this function, the XArray is empty and has freed all memory
+ * allocated for its internal data structures.  You are responsible for
+ * freeing the objects referenced by the XArray.
+ *
+ * Context: Any context.  Takes and releases the xa_lock, interrupt-safe.
+ */
+void xa_destroy(struct xarray *xa)
+{
+       XA_STATE(xas, xa, 0);
+       unsigned long flags;
+       void *entry;
+
+       xas.xa_node = NULL;
+       xas_lock_irqsave(&xas, flags);
+       entry = xa_head_locked(xa);
+       RCU_INIT_POINTER(xa->xa_head, NULL);
+       xas_init_marks(&xas);
+       /* lockdep checks we're still holding the lock in xas_free_nodes() */
+       if (xa_is_node(entry))
+               xas_free_nodes(&xas, xa_to_node(entry));
+       xas_unlock_irqrestore(&xas, flags);
+}
+EXPORT_SYMBOL(xa_destroy);
+
 #ifdef XA_DEBUG
 void xa_dump_node(const struct xa_node *node)
 {