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flex_array: add flex_array_clear function

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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>
This commit is contained in:
David Rientjes 2009-09-21 17:04:30 -07:00 committed by Linus Torvalds
parent 2f30b1f9e1
commit e6de3988aa
2 changed files with 27 additions and 0 deletions
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1
include/linux/flex_array.h
View file

@ -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 */

26
lib/flex_array.c
View file

@ -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