diff options
Diffstat (limited to 'lib/idr.c')
| -rw-r--r-- | lib/idr.c | 255 |
1 files changed, 193 insertions, 62 deletions
diff --git a/lib/idr.c b/lib/idr.c index 2593ce513a18..c98d77fcf393 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -1,4 +1,5 @@ #include <linux/bitmap.h> +#include <linux/bug.h> #include <linux/export.h> #include <linux/idr.h> #include <linux/slab.h> @@ -7,71 +8,184 @@ DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap); static DEFINE_SPINLOCK(simple_ida_lock); -int idr_alloc_cmn(struct idr *idr, void *ptr, unsigned long *index, - unsigned long start, unsigned long end, gfp_t gfp, - bool ext) +/** + * idr_alloc_u32() - Allocate an ID. + * @idr: IDR handle. + * @ptr: Pointer to be associated with the new ID. + * @nextid: Pointer to an ID. + * @max: The maximum ID to allocate (inclusive). + * @gfp: Memory allocation flags. + * + * Allocates an unused ID in the range specified by @nextid and @max. + * Note that @max is inclusive whereas the @end parameter to idr_alloc() + * is exclusive. The new ID is assigned to @nextid before the pointer + * is inserted into the IDR, so if @nextid points into the object pointed + * to by @ptr, a concurrent lookup will not find an uninitialised ID. + * + * The caller should provide their own locking to ensure that two + * concurrent modifications to the IDR are not possible. Read-only + * accesses to the IDR may be done under the RCU read lock or may + * exclude simultaneous writers. + * + * Return: 0 if an ID was allocated, -ENOMEM if memory allocation failed, + * or -ENOSPC if no free IDs could be found. If an error occurred, + * @nextid is unchanged. + */ +int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid, + unsigned long max, gfp_t gfp) { struct radix_tree_iter iter; void __rcu **slot; + int base = idr->idr_base; + int id = *nextid; if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr))) return -EINVAL; + if (WARN_ON_ONCE(!(idr->idr_rt.gfp_mask & ROOT_IS_IDR))) + idr->idr_rt.gfp_mask |= IDR_RT_MARKER; - radix_tree_iter_init(&iter, start); - if (ext) - slot = idr_get_free_ext(&idr->idr_rt, &iter, gfp, end); - else - slot = idr_get_free(&idr->idr_rt, &iter, gfp, end); + id = (id < base) ? 0 : id - base; + radix_tree_iter_init(&iter, id); + slot = idr_get_free(&idr->idr_rt, &iter, gfp, max - base); if (IS_ERR(slot)) return PTR_ERR(slot); + *nextid = iter.index + base; + /* there is a memory barrier inside radix_tree_iter_replace() */ radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr); radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE); - if (index) - *index = iter.index; return 0; } -EXPORT_SYMBOL_GPL(idr_alloc_cmn); +EXPORT_SYMBOL_GPL(idr_alloc_u32); /** - * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion - * @idr: idr handle - * @ptr: pointer to be associated with the new id - * @start: the minimum id (inclusive) - * @end: the maximum id (exclusive) - * @gfp: memory allocation flags - * - * Allocates an ID larger than the last ID allocated if one is available. - * If not, it will attempt to allocate the smallest ID that is larger or - * equal to @start. + * idr_alloc() - Allocate an ID. + * @idr: IDR handle. + * @ptr: Pointer to be associated with the new ID. + * @start: The minimum ID (inclusive). + * @end: The maximum ID (exclusive). + * @gfp: Memory allocation flags. + * + * Allocates an unused ID in the range specified by @start and @end. If + * @end is <= 0, it is treated as one larger than %INT_MAX. This allows + * callers to use @start + N as @end as long as N is within integer range. + * + * The caller should provide their own locking to ensure that two + * concurrent modifications to the IDR are not possible. Read-only + * accesses to the IDR may be done under the RCU read lock or may + * exclude simultaneous writers. + * + * Return: The newly allocated ID, -ENOMEM if memory allocation failed, + * or -ENOSPC if no free IDs could be found. */ -int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) +int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) { - int id, curr = idr->idr_next; + u32 id = start; + int ret; + + if (WARN_ON_ONCE(start < 0)) + return -EINVAL; + + ret = idr_alloc_u32(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp); + if (ret) + return ret; + + return id; +} +EXPORT_SYMBOL_GPL(idr_alloc); - if (curr < start) - curr = start; +/** + * idr_alloc_cyclic() - Allocate an ID cyclically. + * @idr: IDR handle. + * @ptr: Pointer to be associated with the new ID. + * @start: The minimum ID (inclusive). + * @end: The maximum ID (exclusive). + * @gfp: Memory allocation flags. + * + * Allocates an unused ID in the range specified by @nextid and @end. If + * @end is <= 0, it is treated as one larger than %INT_MAX. This allows + * callers to use @start + N as @end as long as N is within integer range. + * The search for an unused ID will start at the last ID allocated and will + * wrap around to @start if no free IDs are found before reaching @end. + * + * The caller should provide their own locking to ensure that two + * concurrent modifications to the IDR are not possible. Read-only + * accesses to the IDR may be done under the RCU read lock or may + * exclude simultaneous writers. + * + * Return: The newly allocated ID, -ENOMEM if memory allocation failed, + * or -ENOSPC if no free IDs could be found. + */ +int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) +{ + u32 id = idr->idr_next; + int err, max = end > 0 ? end - 1 : INT_MAX; - id = idr_alloc(idr, ptr, curr, end, gfp); - if ((id == -ENOSPC) && (curr > start)) - id = idr_alloc(idr, ptr, start, curr, gfp); + if ((int)id < start) + id = start; - if (id >= 0) - idr->idr_next = id + 1U; + err = idr_alloc_u32(idr, ptr, &id, max, gfp); + if ((err == -ENOSPC) && (id > start)) { + id = start; + err = idr_alloc_u32(idr, ptr, &id, max, gfp); + } + if (err) + return err; + idr->idr_next = id + 1; return id; } EXPORT_SYMBOL(idr_alloc_cyclic); /** - * idr_for_each - iterate through all stored pointers - * @idr: idr handle - * @fn: function to be called for each pointer - * @data: data passed to callback function + * idr_remove() - Remove an ID from the IDR. + * @idr: IDR handle. + * @id: Pointer ID. + * + * Removes this ID from the IDR. If the ID was not previously in the IDR, + * this function returns %NULL. + * + * Since this function modifies the IDR, the caller should provide their + * own locking to ensure that concurrent modification of the same IDR is + * not possible. + * + * Return: The pointer formerly associated with this ID. + */ +void *idr_remove(struct idr *idr, unsigned long id) +{ + return radix_tree_delete_item(&idr->idr_rt, id - idr->idr_base, NULL); +} +EXPORT_SYMBOL_GPL(idr_remove); + +/** + * idr_find() - Return pointer for given ID. + * @idr: IDR handle. + * @id: Pointer ID. + * + * Looks up the pointer associated with this ID. A %NULL pointer may + * indicate that @id is not allocated or that the %NULL pointer was + * associated with this ID. + * + * This function can be called under rcu_read_lock(), given that the leaf + * pointers lifetimes are correctly managed. + * + * Return: The pointer associated with this ID. + */ +void *idr_find(const struct idr *idr, unsigned long id) +{ + return radix_tree_lookup(&idr->idr_rt, id - idr->idr_base); +} +EXPORT_SYMBOL_GPL(idr_find); + +/** + * idr_for_each() - Iterate through all stored pointers. + * @idr: IDR handle. + * @fn: Function to be called for each pointer. + * @data: Data passed to callback function. * * The callback function will be called for each entry in @idr, passing - * the id, the pointer and the data pointer passed to this function. + * the ID, the entry and @data. * * If @fn returns anything other than %0, the iteration stops and that * value is returned from this function. @@ -86,9 +200,14 @@ int idr_for_each(const struct idr *idr, { struct radix_tree_iter iter; void __rcu **slot; + int base = idr->idr_base; radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) { - int ret = fn(iter.index, rcu_dereference_raw(*slot), data); + int ret; + + if (WARN_ON_ONCE(iter.index > INT_MAX)) + break; + ret = fn(iter.index + base, rcu_dereference_raw(*slot), data); if (ret) return ret; } @@ -98,9 +217,9 @@ int idr_for_each(const struct idr *idr, EXPORT_SYMBOL(idr_for_each); /** - * idr_get_next - Find next populated entry - * @idr: idr handle - * @nextid: Pointer to lowest possible ID to return + * idr_get_next() - Find next populated entry. + * @idr: IDR handle. + * @nextid: Pointer to an ID. * * Returns the next populated entry in the tree with an ID greater than * or equal to the value pointed to by @nextid. On exit, @nextid is updated @@ -111,35 +230,55 @@ void *idr_get_next(struct idr *idr, int *nextid) { struct radix_tree_iter iter; void __rcu **slot; + int base = idr->idr_base; + int id = *nextid; - slot = radix_tree_iter_find(&idr->idr_rt, &iter, *nextid); + id = (id < base) ? 0 : id - base; + slot = radix_tree_iter_find(&idr->idr_rt, &iter, id); if (!slot) return NULL; + id = iter.index + base; + + if (WARN_ON_ONCE(id > INT_MAX)) + return NULL; - *nextid = iter.index; + *nextid = id; return rcu_dereference_raw(*slot); } EXPORT_SYMBOL(idr_get_next); -void *idr_get_next_ext(struct idr *idr, unsigned long *nextid) +/** + * idr_get_next_ul() - Find next populated entry. + * @idr: IDR handle. + * @nextid: Pointer to an ID. + * + * Returns the next populated entry in the tree with an ID greater than + * or equal to the value pointed to by @nextid. On exit, @nextid is updated + * to the ID of the found value. To use in a loop, the value pointed to by + * nextid must be incremented by the user. + */ +void *idr_get_next_ul(struct idr *idr, unsigned long *nextid) { struct radix_tree_iter iter; void __rcu **slot; + unsigned long base = idr->idr_base; + unsigned long id = *nextid; - slot = radix_tree_iter_find(&idr->idr_rt, &iter, *nextid); + id = (id < base) ? 0 : id - base; + slot = radix_tree_iter_find(&idr->idr_rt, &iter, id); if (!slot) return NULL; - *nextid = iter.index; + *nextid = iter.index + base; return rcu_dereference_raw(*slot); } -EXPORT_SYMBOL(idr_get_next_ext); +EXPORT_SYMBOL(idr_get_next_ul); /** - * idr_replace - replace pointer for given id - * @idr: idr handle - * @ptr: New pointer to associate with the ID - * @id: Lookup key + * idr_replace() - replace pointer for given ID. + * @idr: IDR handle. + * @ptr: New pointer to associate with the ID. + * @id: ID to change. * * Replace the pointer registered with an ID and return the old value. * This function can be called under the RCU read lock concurrently with @@ -147,18 +286,9 @@ EXPORT_SYMBOL(idr_get_next_ext); * the one being replaced!). * * Returns: the old value on success. %-ENOENT indicates that @id was not - * found. %-EINVAL indicates that @id or @ptr were not valid. + * found. %-EINVAL indicates that @ptr was not valid. */ -void *idr_replace(struct idr *idr, void *ptr, int id) -{ - if (id < 0) - return ERR_PTR(-EINVAL); - - return idr_replace_ext(idr, ptr, id); -} -EXPORT_SYMBOL(idr_replace); - -void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id) +void *idr_replace(struct idr *idr, void *ptr, unsigned long id) { struct radix_tree_node *node; void __rcu **slot = NULL; @@ -166,6 +296,7 @@ void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id) if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr))) return ERR_PTR(-EINVAL); + id -= idr->idr_base; entry = __radix_tree_lookup(&idr->idr_rt, id, &node, &slot); if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE)) @@ -175,7 +306,7 @@ void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id) return entry; } -EXPORT_SYMBOL(idr_replace_ext); +EXPORT_SYMBOL(idr_replace); /** * DOC: IDA description @@ -235,7 +366,7 @@ EXPORT_SYMBOL(idr_replace_ext); * bitmap, which is excessive. */ -#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS) +#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1) /** * ida_get_new_above - allocate new ID above or equal to a start id |