diff options
Diffstat (limited to 'lib/idr.c')
| -rw-r--r-- | lib/idr.c | 43 |
1 files changed, 43 insertions, 0 deletions
@@ -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) { |