diff options
authorEric Paris <eparis@redhat.com>2010-08-09 17:20:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-09 20:45:09 -0700
commitea98eed9bcb62d1319db8b1210712c6a110a886c (patch)
parent559b140a36613bb5b63f258b2ad833dad8cd11d9 (diff)
flex_array: add helpers to get and put to make pointers easy to use
Getting and putting arrays of pointers with flex arrays is a PITA. You have to remember to pass &ptr to the _put and you have to do weird and wacky casting to get the ptr back from the _get. Add two functions flex_array_get_ptr() and flex_array_put_ptr() to handle all of the magic. [akpm@linux-foundation.org: simplification suggested by Joe] Signed-off-by: Eric Paris <eparis@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Joe Perches <joe@perches.com> Cc: James Morris <jmorris@namei.org> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2 files changed, 29 insertions, 1 deletions
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
index 1d747f72298b..631b77f2ac70 100644
--- a/include/linux/flex_array.h
+++ b/include/linux/flex_array.h
@@ -70,4 +70,9 @@ int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
int flex_array_shrink(struct flex_array *fa);
+#define flex_array_put_ptr(fa, nr, src, gfp) \
+ flex_array_put(fa, nr, &(void *)(src), gfp)
+void *flex_array_get_ptr(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 41b1804fa728..77a6fea7481e 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -171,6 +171,8 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags)
* Note that this *copies* the contents of @src into
* the array. If you are trying to store an array of
* pointers, make sure to pass in &ptr instead of ptr.
+ * You may instead wish to use the flex_array_put_ptr()
+ * helper function.
* Locking must be provided by the caller.
@@ -265,7 +267,8 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start,
* Returns a pointer to the data at index @element_nr. Note
* that this is a copy of the data that was passed in. If you
- * are using this to store pointers, you'll get back &ptr.
+ * are using this to store pointers, you'll get back &ptr. You
+ * may instead wish to use the flex_array_get_ptr helper.
* Locking must be provided by the caller.
@@ -286,6 +289,26 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
return &part->elements[index_inside_part(fa, element_nr)];
+ * flex_array_get_ptr - pull a ptr back out of the array
+ * @fa: the flex array from which to extract data
+ * @element_nr: index of the element to fetch from the array
+ *
+ * Returns the pointer placed in the flex array at element_nr using
+ * flex_array_put_ptr(). This function should not be called if the
+ * element in question was not set using the _put_ptr() helper.
+ */
+void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr)
+ void **tmp;
+ tmp = flex_array_get(fa, element_nr);
+ if (!tmp)
+ return NULL;
+ return *tmp;
static int part_is_free(struct flex_array_part *part)
int i;

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