This patch adds an idr_replace() method to the IDR library for replacing
a pointer already present in the IDR. Rather than do a remove/add pair, this
function simply updates the pointer for an ID.
Signed-off-by: Jeff Mahoney <[email protected]>
--
include/linux/idr.h | 1 +
lib/idr.c | 37 +++++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
diff -ruNpX ../dontdiff linux-2.6.16-staging1/include/linux/idr.h linux-2.6.16-staging2/include/linux/idr.h
--- linux-2.6.16-staging1/include/linux/idr.h 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.16-staging2/include/linux/idr.h 2006-04-13 16:18:14.000000000 -0400
@@ -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);
+int 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);
diff -ruNpX ../dontdiff linux-2.6.16-staging1/lib/idr.c linux-2.6.16-staging2/lib/idr.c
--- linux-2.6.16-staging1/lib/idr.c 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.16-staging2/lib/idr.c 2006-04-13 16:18:14.000000000 -0400
@@ -390,6 +390,43 @@ 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 ide
+ * @id: lookup key
+ *
+ * Replace the pointer registered with the id. A -ENOENT
+ * return indicates that @id was not found.
+ *
+ * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().
+ */
+int idr_replace(struct idr *idp, void *ptr, int id)
+{
+ int n;
+ struct idr_layer *p;
+ int shift = (idp->layers - 1) * IDR_BITS;
+
+ n = idp->layers * IDR_BITS;
+ p = idp->top;
+
+ id &= MAX_ID_MASK;
+
+ while ((shift > 0) && p) {
+ n = (id >> shift) & IDR_MASK;
+ p = p->ary[n];
+ shift -= IDR_BITS;
+ }
+
+ n = id & IDR_MASK;
+ if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
+ return -ENOENT;
+
+ p->ary[n] = ptr;
+ return 0;
+}
+EXPORT_SYMBOL(idr_replace);
+
static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache,
unsigned long flags)
{
-
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