From e6de3988aa52debb25a427d085061f3bf1181d54 Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Mon, 21 Sep 2009 17:04:30 -0700
Subject: [PATCH] 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>
---
include/linux/flex_array.h | 1 +
lib/flex_array.c | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
index 45ff18491514..3887b21f883f 100644
--- a/include/linux/flex_array.h
+++ b/include/linux/flex_array.h
@@ -44,6 +44,7 @@ void flex_array_free(struct flex_array *fa);
void flex_array_free_parts(struct flex_array *fa);
int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
gfp_t flags);
+int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
#endif /* _FLEX_ARRAY_H */
diff --git a/lib/flex_array.c b/lib/flex_array.c
index 7baed2fc3bc8..b68f99be4080 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -206,6 +206,32 @@ int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
return 0;
}
+/**
+ * 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
--
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