Commit e6de3988 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

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: default avatarDavid Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2f30b1f9

include/linux/flex_array.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

lib/flex_array.c

+26 −0
Original line number Diff line number Diff line
@@ -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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