Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5806f07c authored by Jeff Mahoney's avatar Jeff Mahoney Committed by Linus Torvalds
Browse files

[PATCH] lib: add idr_replace 



This patch adds idr_replace() to replace an existing pointer in a single
operation.

Device-mapper will use this to update the pointer it stored against a given
id.

Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c51c2752

include/linux/idr.h

+1 −0
Original line number Diff line number Diff line
@@ -78,6 +78,7 @@ void *idr_find(struct idr *idp, int id); 
int idr_pre_get(struct idr *idp, gfp_t gfp_mask);

int idr_get_new(struct idr *idp, void *ptr, int *id);

int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);

void *idr_replace(struct idr *idp, void *ptr, int id);

void idr_remove(struct idr *idp, int id);

void idr_destroy(struct idr *idp);

void idr_init(struct idr *idp);

lib/idr.c

+43 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/init.h>

#include <linux/module.h>

#endif

#include <linux/err.h>

#include <linux/string.h>

#include <linux/idr.h>
@@ -398,6 +399,48 @@ void *idr_find(struct idr *idp, int id) 
}

EXPORT_SYMBOL(idr_find);



/**

 * idr_replace - replace pointer for given id

 * @idp: idr handle

 * @ptr: pointer you want associated with the id

 * @id: lookup key

 *

 * Replace the pointer registered with an id and return the old value.

 * A -ENOENT return indicates that @id was not found.

 * A -EINVAL return indicates that @id was not within valid constraints.

 *

 * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().

 */

void *idr_replace(struct idr *idp, void *ptr, int id)

{

	int n;

	struct idr_layer *p, *old_p;



	n = idp->layers * IDR_BITS;

	p = idp->top;



	id &= MAX_ID_MASK;



	if (id >= (1 << n))

		return ERR_PTR(-EINVAL);



	n -= IDR_BITS;

	while ((n > 0) && p) {

		p = p->ary[(id >> n) & IDR_MASK];

		n -= IDR_BITS;

	}



	n = id & IDR_MASK;

	if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))

		return ERR_PTR(-ENOENT);



	old_p = p->ary[n];

	p->ary[n] = ptr;



	return old_p;

}

EXPORT_SYMBOL(idr_replace);



static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache,

		unsigned long flags)

{