diff options
| -rw-r--r-- | include/linux/idr.h | 2 | ||||
| -rw-r--r-- | lib/idr.c | 27 |
2 files changed, 29 insertions, 0 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h index 2640c7e99e5..a470ac3ef49 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -42,6 +42,7 @@ struct idr { struct idr_layer *id_free; int layers; /* only valid w/o concurrent changes */ int id_free_cnt; + int cur; /* current pos for cyclic allocation */ spinlock_t lock; }; @@ -75,6 +76,7 @@ struct idr { void *idr_find_slowpath(struct idr *idp, int id); void idr_preload(gfp_t gfp_mask); int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); +int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask); int idr_for_each(struct idr *idp, int (*fn)(int id, void *p, void *data), void *data); void *idr_get_next(struct idr *idp, int *nextid); diff --git a/lib/idr.c b/lib/idr.c index 322e2816f2f..cca4b9302a7 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -495,6 +495,33 @@ int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask) } EXPORT_SYMBOL_GPL(idr_alloc); +/** + * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion + * @idr: the (initialized) idr + * @ptr: pointer to be associated with the new id + * @start: the minimum id (inclusive) + * @end: the maximum id (exclusive, <= 0 for max) + * @gfp_mask: memory allocation flags + * + * Essentially the same as idr_alloc, but prefers to allocate progressively + * higher ids if it can. If the "cur" counter wraps, then it will start again + * at the "start" end of the range and allocate one that has already been used. + */ +int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, + gfp_t gfp_mask) +{ + int id; + + id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask); + if (id == -ENOSPC) + id = idr_alloc(idr, ptr, start, end, gfp_mask); + + if (likely(id >= 0)) + idr->cur = id + 1; + return id; +} +EXPORT_SYMBOL(idr_alloc_cyclic); + static void idr_remove_warning(int id) { printk(KERN_WARNING |