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-rw-r--r--lib/idr.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/lib/idr.c b/lib/idr.c
index de19030a999b..4d096819511a 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -29,6 +29,7 @@
29#include <linux/init.h> 29#include <linux/init.h>
30#include <linux/module.h> 30#include <linux/module.h>
31#endif 31#endif
32#include <linux/err.h>
32#include <linux/string.h> 33#include <linux/string.h>
33#include <linux/idr.h> 34#include <linux/idr.h>
34 35
@@ -398,6 +399,48 @@ void *idr_find(struct idr *idp, int id)
398} 399}
399EXPORT_SYMBOL(idr_find); 400EXPORT_SYMBOL(idr_find);
400 401
402/**
403 * idr_replace - replace pointer for given id
404 * @idp: idr handle
405 * @ptr: pointer you want associated with the id
406 * @id: lookup key
407 *
408 * Replace the pointer registered with an id and return the old value.
409 * A -ENOENT return indicates that @id was not found.
410 * A -EINVAL return indicates that @id was not within valid constraints.
411 *
412 * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().
413 */
414void *idr_replace(struct idr *idp, void *ptr, int id)
415{
416 int n;
417 struct idr_layer *p, *old_p;
418
419 n = idp->layers * IDR_BITS;
420 p = idp->top;
421
422 id &= MAX_ID_MASK;
423
424 if (id >= (1 << n))
425 return ERR_PTR(-EINVAL);
426
427 n -= IDR_BITS;
428 while ((n > 0) && p) {
429 p = p->ary[(id >> n) & IDR_MASK];
430 n -= IDR_BITS;
431 }
432
433 n = id & IDR_MASK;
434 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
435 return ERR_PTR(-ENOENT);
436
437 old_p = p->ary[n];
438 p->ary[n] = ptr;
439
440 return old_p;
441}
442EXPORT_SYMBOL(idr_replace);
443
401static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache, 444static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache,
402 unsigned long flags) 445 unsigned long flags)
403{ 446{