flex_array: add flex_array_clear function
Add a new function to the flex_array API:
int flex_array_clear(struct flex_array *fa,
unsigned int element_nr)
This function will zero the element at element_nr in the flex_array.
Although this is equivalent to using flex_array_put() and passing a
pointer to zero'd memory, flex_array_clear() does not require such a
pointer to memory that would most likely need to be allocated on the
caller's stack which could be significantly large depending on
element_size.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/flex_array.c b/lib/flex_array.c
index 7baed2f..b68f99b 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -207,6 +207,32 @@
}
/**
+ * flex_array_clear - clear element in array at @element_nr
+ * @element_nr: index of the position to clear.
+ *
+ * Locking must be provided by the caller.
+ */
+int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
+{
+ int part_nr = fa_element_to_part_nr(fa, element_nr);
+ struct flex_array_part *part;
+ void *dst;
+
+ if (element_nr >= fa->total_nr_elements)
+ return -ENOSPC;
+ if (elements_fit_in_base(fa))
+ part = (struct flex_array_part *)&fa->parts[0];
+ else {
+ part = fa->parts[part_nr];
+ if (!part)
+ return -EINVAL;
+ }
+ dst = &part->elements[index_inside_part(fa, element_nr)];
+ memset(dst, 0, fa->element_size);
+ return 0;
+}
+
+/**
* flex_array_prealloc - guarantee that array space exists
* @start: index of first array element for which space is allocated
* @end: index of last (inclusive) element for which space is allocated