Messages in this thread Patch in this message | | | Date | Thu, 25 May 2006 20:10:12 +0100 | From | Alasdair G Kergon <> | Subject | [PATCH 2/10] lib: add idr_replace |
| |
From: Jeff Mahoney <jeffm@suse.com>
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: Jeff Mahoney <jeffm@suse.com> Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
Index: linux-2.6.17-rc4/include/linux/idr.h =================================================================== --- linux-2.6.17-rc4.orig/include/linux/idr.h 2006-05-23 18:16:31.000000000 +0100 +++ linux-2.6.17-rc4/include/linux/idr.h 2006-05-23 18:16:40.000000000 +0100 @@ -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); Index: linux-2.6.17-rc4/lib/idr.c =================================================================== --- linux-2.6.17-rc4.orig/lib/idr.c 2006-05-23 18:16:31.000000000 +0100 +++ linux-2.6.17-rc4/lib/idr.c 2006-05-23 18:16:40.000000000 +0100 @@ -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> @@ -390,6 +391,48 @@ 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 (void *)old_p; +} +EXPORT_SYMBOL(idr_replace); + static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache, unsigned long flags) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |