| // SPDX-License-Identifier: GPL-2.0-only |
| #include <linux/bitmap.h> |
| #include <linux/bug.h> |
| #include <linux/export.h> |
| #include <linux/idr.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/xarray.h> |
| |
| /** |
| * 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; |
| unsigned int base = idr->idr_base; |
| unsigned int id = *nextid; |
| |
| if (WARN_ON_ONCE(!(idr->idr_rt.xa_flags & ROOT_IS_IDR))) |
| idr->idr_rt.xa_flags |= IDR_RT_MARKER; |
| |
| 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); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(idr_alloc_u32); |
| |
| /** |
| * 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(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) |
| { |
| 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); |
| |
| /** |
| * 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; |
| |
| if ((int)id < start) |
| id = start; |
| |
| 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_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 entry and @data. |
| * |
| * If @fn returns anything other than %0, the iteration stops and that |
| * value is returned from this function. |
| * |
| * idr_for_each() can be called concurrently with idr_alloc() and |
| * idr_remove() if protected by RCU. Newly added entries may not be |
| * seen and deleted entries may be seen, but adding and removing entries |
| * will not cause other entries to be skipped, nor spurious ones to be seen. |
| */ |
| int idr_for_each(const struct idr *idr, |
| int (*fn)(int id, void *p, void *data), void *data) |
| { |
| 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; |
| unsigned long id = iter.index + base; |
| |
| if (WARN_ON_ONCE(id > INT_MAX)) |
| break; |
| ret = fn(id, rcu_dereference_raw(*slot), data); |
| if (ret) |
| return ret; |
| } |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(idr_for_each); |
| |
| /** |
| * 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; |
| void *entry = NULL; |
| unsigned long base = idr->idr_base; |
| unsigned long id = *nextid; |
| |
| id = (id < base) ? 0 : id - base; |
| radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, id) { |
| entry = rcu_dereference_raw(*slot); |
| if (!entry) |
| continue; |
| if (!xa_is_internal(entry)) |
| break; |
| if (slot != &idr->idr_rt.xa_head && !xa_is_retry(entry)) |
| break; |
| slot = radix_tree_iter_retry(&iter); |
| } |
| if (!slot) |
| return NULL; |
| |
| *nextid = iter.index + base; |
| return entry; |
| } |
| EXPORT_SYMBOL(idr_get_next_ul); |
| |
| /** |
| * 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 |
| * 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(struct idr *idr, int *nextid) |
| { |
| unsigned long id = *nextid; |
| void *entry = idr_get_next_ul(idr, &id); |
| |
| if (WARN_ON_ONCE(id > INT_MAX)) |
| return NULL; |
| *nextid = id; |
| return entry; |
| } |
| EXPORT_SYMBOL(idr_get_next); |
| |
| /** |
| * 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 |
| * idr_alloc() and idr_remove() (as long as the ID being removed is not |
| * the one being replaced!). |
| * |
| * Returns: the old value on success. %-ENOENT indicates that @id was not |
| * found. %-EINVAL indicates that @ptr was not valid. |
| */ |
| void *idr_replace(struct idr *idr, void *ptr, unsigned long id) |
| { |
| struct radix_tree_node *node; |
| void __rcu **slot = NULL; |
| void *entry; |
| |
| 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)) |
| return ERR_PTR(-ENOENT); |
| |
| __radix_tree_replace(&idr->idr_rt, node, slot, ptr); |
| |
| return entry; |
| } |
| EXPORT_SYMBOL(idr_replace); |
| |
| /** |
| * DOC: IDA description |
| * |
| * The IDA is an ID allocator which does not provide the ability to |
| * associate an ID with a pointer. As such, it only needs to store one |
| * bit per ID, and so is more space efficient than an IDR. To use an IDA, |
| * define it using DEFINE_IDA() (or embed a &struct ida in a data structure, |
| * then initialise it using ida_init()). To allocate a new ID, call |
| * ida_alloc(), ida_alloc_min(), ida_alloc_max() or ida_alloc_range(). |
| * To free an ID, call ida_free(). |
| * |
| * ida_destroy() can be used to dispose of an IDA without needing to |
| * free the individual IDs in it. You can use ida_is_empty() to find |
| * out whether the IDA has any IDs currently allocated. |
| * |
| * The IDA handles its own locking. It is safe to call any of the IDA |
| * functions without synchronisation in your code. |
| * |
| * IDs are currently limited to the range [0-INT_MAX]. If this is an awkward |
| * limitation, it should be quite straightforward to raise the maximum. |
| */ |
| |
| /* |
| * Developer's notes: |
| * |
| * The IDA uses the functionality provided by the XArray to store bitmaps in |
| * each entry. The XA_FREE_MARK is only cleared when all bits in the bitmap |
| * have been set. |
| * |
| * I considered telling the XArray that each slot is an order-10 node |
| * and indexing by bit number, but the XArray can't allow a single multi-index |
| * entry in the head, which would significantly increase memory consumption |
| * for the IDA. So instead we divide the index by the number of bits in the |
| * leaf bitmap before doing a radix tree lookup. |
| * |
| * As an optimisation, if there are only a few low bits set in any given |
| * leaf, instead of allocating a 128-byte bitmap, we store the bits |
| * as a value entry. Value entries never have the XA_FREE_MARK cleared |
| * because we can always convert them into a bitmap entry. |
| * |
| * It would be possible to optimise further; once we've run out of a |
| * single 128-byte bitmap, we currently switch to a 576-byte node, put |
| * the 128-byte bitmap in the first entry and then start allocating extra |
| * 128-byte entries. We could instead use the 512 bytes of the node's |
| * data as a bitmap before moving to that scheme. I do not believe this |
| * is a worthwhile optimisation; Rasmus Villemoes surveyed the current |
| * users of the IDA and almost none of them use more than 1024 entries. |
| * Those that do use more than the 8192 IDs that the 512 bytes would |
| * provide. |
| * |
| * The IDA always uses a lock to alloc/free. If we add a 'test_bit' |
| * equivalent, it will still need locking. Going to RCU lookup would require |
| * using RCU to free bitmaps, and that's not trivial without embedding an |
| * RCU head in the bitmap, which adds a 2-pointer overhead to each 128-byte |
| * bitmap, which is excessive. |
| */ |
| |
| /** |
| * ida_alloc_range() - Allocate an unused ID. |
| * @ida: IDA handle. |
| * @min: Lowest ID to allocate. |
| * @max: Highest ID to allocate. |
| * @gfp: Memory allocation flags. |
| * |
| * Allocate an ID between @min and @max, inclusive. The allocated ID will |
| * not exceed %INT_MAX, even if @max is larger. |
| * |
| * Context: Any context. It is safe to call this function without |
| * locking in your code. |
| * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, |
| * or %-ENOSPC if there are no free IDs. |
| */ |
| int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max, |
| gfp_t gfp) |
| { |
| XA_STATE(xas, &ida->xa, min / IDA_BITMAP_BITS); |
| unsigned bit = min % IDA_BITMAP_BITS; |
| unsigned long flags; |
| struct ida_bitmap *bitmap, *alloc = NULL; |
| |
| if ((int)min < 0) |
| return -ENOSPC; |
| |
| if ((int)max < 0) |
| max = INT_MAX; |
| |
| retry: |
| xas_lock_irqsave(&xas, flags); |
| next: |
| bitmap = xas_find_marked(&xas, max / IDA_BITMAP_BITS, XA_FREE_MARK); |
| if (xas.xa_index > min / IDA_BITMAP_BITS) |
| bit = 0; |
| if (xas.xa_index * IDA_BITMAP_BITS + bit > max) |
| goto nospc; |
| |
| if (xa_is_value(bitmap)) { |
| unsigned long tmp = xa_to_value(bitmap); |
| |
| if (bit < BITS_PER_XA_VALUE) { |
| bit = find_next_zero_bit(&tmp, BITS_PER_XA_VALUE, bit); |
| if (xas.xa_index * IDA_BITMAP_BITS + bit > max) |
| goto nospc; |
| if (bit < BITS_PER_XA_VALUE) { |
| tmp |= 1UL << bit; |
| xas_store(&xas, xa_mk_value(tmp)); |
| goto out; |
| } |
| } |
| bitmap = alloc; |
| if (!bitmap) |
| bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT); |
| if (!bitmap) |
| goto alloc; |
| bitmap->bitmap[0] = tmp; |
| xas_store(&xas, bitmap); |
| if (xas_error(&xas)) { |
| bitmap->bitmap[0] = 0; |
| goto out; |
| } |
| } |
| |
| if (bitmap) { |
| bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit); |
| if (xas.xa_index * IDA_BITMAP_BITS + bit > max) |
| goto nospc; |
| if (bit == IDA_BITMAP_BITS) |
| goto next; |
| |
| __set_bit(bit, bitmap->bitmap); |
| if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS)) |
| xas_clear_mark(&xas, XA_FREE_MARK); |
| } else { |
| if (bit < BITS_PER_XA_VALUE) { |
| bitmap = xa_mk_value(1UL << bit); |
| } else { |
| bitmap = alloc; |
| if (!bitmap) |
| bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT); |
| if (!bitmap) |
| goto alloc; |
| __set_bit(bit, bitmap->bitmap); |
| } |
| xas_store(&xas, bitmap); |
| } |
| out: |
| xas_unlock_irqrestore(&xas, flags); |
| if (xas_nomem(&xas, gfp)) { |
| xas.xa_index = min / IDA_BITMAP_BITS; |
| bit = min % IDA_BITMAP_BITS; |
| goto retry; |
| } |
| if (bitmap != alloc) |
| kfree(alloc); |
| if (xas_error(&xas)) |
| return xas_error(&xas); |
| return xas.xa_index * IDA_BITMAP_BITS + bit; |
| alloc: |
| xas_unlock_irqrestore(&xas, flags); |
| alloc = kzalloc(sizeof(*bitmap), gfp); |
| if (!alloc) |
| return -ENOMEM; |
| xas_set(&xas, min / IDA_BITMAP_BITS); |
| bit = min % IDA_BITMAP_BITS; |
| goto retry; |
| nospc: |
| xas_unlock_irqrestore(&xas, flags); |
| return -ENOSPC; |
| } |
| EXPORT_SYMBOL(ida_alloc_range); |
| |
| /** |
| * ida_free() - Release an allocated ID. |
| * @ida: IDA handle. |
| * @id: Previously allocated ID. |
| * |
| * Context: Any context. It is safe to call this function without |
| * locking in your code. |
| */ |
| void ida_free(struct ida *ida, unsigned int id) |
| { |
| XA_STATE(xas, &ida->xa, id / IDA_BITMAP_BITS); |
| unsigned bit = id % IDA_BITMAP_BITS; |
| struct ida_bitmap *bitmap; |
| unsigned long flags; |
| |
| BUG_ON((int)id < 0); |
| |
| xas_lock_irqsave(&xas, flags); |
| bitmap = xas_load(&xas); |
| |
| if (xa_is_value(bitmap)) { |
| unsigned long v = xa_to_value(bitmap); |
| if (bit >= BITS_PER_XA_VALUE) |
| goto err; |
| if (!(v & (1UL << bit))) |
| goto err; |
| v &= ~(1UL << bit); |
| if (!v) |
| goto delete; |
| xas_store(&xas, xa_mk_value(v)); |
| } else { |
| if (!test_bit(bit, bitmap->bitmap)) |
| goto err; |
| __clear_bit(bit, bitmap->bitmap); |
| xas_set_mark(&xas, XA_FREE_MARK); |
| if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) { |
| kfree(bitmap); |
| delete: |
| xas_store(&xas, NULL); |
| } |
| } |
| xas_unlock_irqrestore(&xas, flags); |
| return; |
| err: |
| xas_unlock_irqrestore(&xas, flags); |
| WARN(1, "ida_free called for id=%d which is not allocated.\n", id); |
| } |
| EXPORT_SYMBOL(ida_free); |
| |
| /** |
| * ida_destroy() - Free all IDs. |
| * @ida: IDA handle. |
| * |
| * Calling this function frees all IDs and releases all resources used |
| * by an IDA. When this call returns, the IDA is empty and can be reused |
| * or freed. If the IDA is already empty, there is no need to call this |
| * function. |
| * |
| * Context: Any context. It is safe to call this function without |
| * locking in your code. |
| */ |
| void ida_destroy(struct ida *ida) |
| { |
| XA_STATE(xas, &ida->xa, 0); |
| struct ida_bitmap *bitmap; |
| unsigned long flags; |
| |
| xas_lock_irqsave(&xas, flags); |
| xas_for_each(&xas, bitmap, ULONG_MAX) { |
| if (!xa_is_value(bitmap)) |
| kfree(bitmap); |
| xas_store(&xas, NULL); |
| } |
| xas_unlock_irqrestore(&xas, flags); |
| } |
| EXPORT_SYMBOL(ida_destroy); |
| |
| #ifndef __KERNEL__ |
| extern void xa_dump_index(unsigned long index, unsigned int shift); |
| #define IDA_CHUNK_SHIFT ilog2(IDA_BITMAP_BITS) |
| |
| static void ida_dump_entry(void *entry, unsigned long index) |
| { |
| unsigned long i; |
| |
| if (!entry) |
| return; |
| |
| if (xa_is_node(entry)) { |
| struct xa_node *node = xa_to_node(entry); |
| unsigned int shift = node->shift + IDA_CHUNK_SHIFT + |
| XA_CHUNK_SHIFT; |
| |
| xa_dump_index(index * IDA_BITMAP_BITS, shift); |
| xa_dump_node(node); |
| for (i = 0; i < XA_CHUNK_SIZE; i++) |
| ida_dump_entry(node->slots[i], |
| index | (i << node->shift)); |
| } else if (xa_is_value(entry)) { |
| xa_dump_index(index * IDA_BITMAP_BITS, ilog2(BITS_PER_LONG)); |
| pr_cont("value: data %lx [%px]\n", xa_to_value(entry), entry); |
| } else { |
| struct ida_bitmap *bitmap = entry; |
| |
| xa_dump_index(index * IDA_BITMAP_BITS, IDA_CHUNK_SHIFT); |
| pr_cont("bitmap: %p data", bitmap); |
| for (i = 0; i < IDA_BITMAP_LONGS; i++) |
| pr_cont(" %lx", bitmap->bitmap[i]); |
| pr_cont("\n"); |
| } |
| } |
| |
| static void ida_dump(struct ida *ida) |
| { |
| struct xarray *xa = &ida->xa; |
| pr_debug("ida: %p node %p free %d\n", ida, xa->xa_head, |
| xa->xa_flags >> ROOT_TAG_SHIFT); |
| ida_dump_entry(xa->xa_head, 0); |
| } |
| #endif |