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Release 4.12 lib/idr.c

Directory: lib
#include <linux/bitmap.h>
#include <linux/export.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);
static DEFINE_SPINLOCK(simple_ida_lock);

 * 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 [start, end).  Returns -ENOSPC
 * if there are no unused IDs in that range.
 * Note that @end is treated as max when <= 0.  This is to always allow
 * using @start + N as @end as long as N is inside integer range.
 * Simultaneous modifications to the @idr are not allowed and should be
 * prevented by the user, usually with a lock.  idr_alloc() may be called
 * concurrently with read-only accesses to the @idr, such as idr_find() and
 * idr_for_each_entry().

int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) { void __rcu **slot; struct radix_tree_iter iter; if (WARN_ON_ONCE(start < 0)) return -EINVAL; if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr))) return -EINVAL; radix_tree_iter_init(&iter, start); slot = idr_get_free(&idr->idr_rt, &iter, gfp, end); if (IS_ERR(slot)) return PTR_ERR(slot); radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr); radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE); return iter.index; }


Matthew Wilcox8161.83%215.38%
Tejun Heo2519.08%646.15%
George Anzinger1410.69%17.69%
Kamezawa Hiroyuki75.34%17.69%
Nadia Derbey21.53%17.69%
Sonny Rao10.76%17.69%
Roland Dreier10.76%17.69%

EXPORT_SYMBOL_GPL(idr_alloc); /** * 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. */
int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) { int id, curr = idr->idr_next; if (curr < start) curr = start; id = idr_alloc(idr, ptr, curr, end, gfp); if ((id == -ENOSPC) && (curr > start)) id = idr_alloc(idr, ptr, start, curr, gfp); if (id >= 0) idr->idr_next = id + 1U; return id; }


Matthew Wilcox6259.62%120.00%
Jeff Mahoney3331.73%120.00%
Tejun Heo43.85%120.00%
Lai Jiangshan32.88%120.00%
Manfred Spraul21.92%120.00%

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 * * The callback function will be called for each entry in @idr, passing * the id, the pointer and the data pointer passed to this function. * * 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; radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) { int ret = fn(iter.index, rcu_dereference_raw(*slot), data); if (ret) return ret; } return 0; }


Matthew Wilcox7084.34%266.67%
George Anzinger1315.66%133.33%

EXPORT_SYMBOL(idr_for_each); /** * idr_get_next - Find next populated entry * @idr: idr handle * @nextid: Pointer to lowest possible ID to return * * 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) { struct radix_tree_iter iter; void __rcu **slot; slot = radix_tree_iter_find(&idr->idr_rt, &iter, *nextid); if (!slot) return NULL; *nextid = iter.index; return rcu_dereference_raw(*slot); }


Matthew Wilcox4876.19%266.67%
Andreas Gruenbacher1523.81%133.33%

EXPORT_SYMBOL(idr_get_next); /** * idr_replace - replace pointer for given id * @idr: idr handle * @ptr: New pointer to associate with the ID * @id: Lookup key * * 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: 0 on success. %-ENOENT indicates that @id was not found. * %-EINVAL indicates that @id or @ptr were not valid. */
void *idr_replace(struct idr *idr, void *ptr, int id) { struct radix_tree_node *node; void __rcu **slot = NULL; void *entry; if (WARN_ON_ONCE(id < 0)) return ERR_PTR(-EINVAL); if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr))) return ERR_PTR(-EINVAL); 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, NULL, NULL); return entry; }


Matthew Wilcox10177.10%266.67%
Tejun Heo3022.90%133.33%

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_simple_get(). To free an ID, call ida_simple_remove(). * * If you have more complex locking requirements, use a loop around * ida_pre_get() and ida_get_new() to allocate a new ID. Then use * ida_remove() to free an ID. You must make sure that ida_get_new() and * ida_remove() cannot be called at the same time as each other for the * same IDA. * * You can also use ida_get_new_above() if you need an ID to be allocated * above a particular number. 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. * * 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 IDR & radix tree to store * bitmaps in each entry. The IDR_FREE tag means there is at least one bit * free, unlike the IDR where it means at least one entry is free. * * I considered telling the radix tree that each slot is an order-10 node * and storing the bit numbers in the radix tree, but the radix tree can't * allow a single multiorder entry at index 0, 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 use the 'exceptional * entry' functionality of the radix tree to store BITS_PER_LONG - 2 bits * directly in the entry. By being really tricksy, we could store * BITS_PER_LONG - 1 bits, but there're diminishing returns after optimising * for 0-3 allocated IDs. * * We allow the radix tree 'exceptional' count to get out of date. Nothing * in the IDA nor the radix tree code checks it. If it becomes important * to maintain an accurate exceptional count, switch the rcu_assign_pointer() * calls to radix_tree_iter_replace() which will correct the exceptional * count. * * The IDA always requires 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. */ #define IDA_MAX (0x80000000U / IDA_BITMAP_BITS) /** * ida_get_new_above - allocate new ID above or equal to a start id * @ida: ida handle * @start: id to start search at * @id: pointer to the allocated handle * * Allocate new ID above or equal to @start. It should be called * with any required locks to ensure that concurrent calls to * ida_get_new_above() / ida_get_new() / ida_remove() are not allowed. * Consider using ida_simple_get() if you do not have complex locking * requirements. * * If memory is required, it will return %-EAGAIN, you should unlock * and go back to the ida_pre_get() call. If the ida is full, it will * return %-ENOSPC. On success, it will return 0. * * @id returns a value in the range @start ... %0x7fffffff. */
int ida_get_new_above(struct ida *ida, int start, int *id) { struct radix_tree_root *root = &ida->ida_rt; void __rcu **slot; struct radix_tree_iter iter; struct ida_bitmap *bitmap; unsigned long index; unsigned bit, ebit; int new; index = start / IDA_BITMAP_BITS; bit = start % IDA_BITMAP_BITS; ebit = bit + RADIX_TREE_EXCEPTIONAL_SHIFT; slot = radix_tree_iter_init(&iter, index); for (;;) { if (slot) slot = radix_tree_next_slot(slot, &iter, RADIX_TREE_ITER_TAGGED); if (!slot) { slot = idr_get_free(root, &iter, GFP_NOWAIT, IDA_MAX); if (IS_ERR(slot)) { if (slot == ERR_PTR(-ENOMEM)) return -EAGAIN; return PTR_ERR(slot); } } if (iter.index > index) { bit = 0; ebit = RADIX_TREE_EXCEPTIONAL_SHIFT; } new = iter.index * IDA_BITMAP_BITS; bitmap = rcu_dereference_raw(*slot); if (radix_tree_exception(bitmap)) { unsigned long tmp = (unsigned long)bitmap; ebit = find_next_zero_bit(&tmp, BITS_PER_LONG, ebit); if (ebit < BITS_PER_LONG) { tmp |= 1UL << ebit; rcu_assign_pointer(*slot, (void *)tmp); *id = new + ebit - RADIX_TREE_EXCEPTIONAL_SHIFT; return 0; } bitmap = this_cpu_xchg(ida_bitmap, NULL); if (!bitmap) return -EAGAIN; memset(bitmap, 0, sizeof(*bitmap)); bitmap->bitmap[0] = tmp >> RADIX_TREE_EXCEPTIONAL_SHIFT; rcu_assign_pointer(*slot, bitmap); } if (bitmap) { bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit); new += bit; if (new < 0) return -ENOSPC; if (bit == IDA_BITMAP_BITS) continue; __set_bit(bit, bitmap->bitmap); if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS)) radix_tree_iter_tag_clear(root, &iter, IDR_FREE); } else { new += bit; if (new < 0) return -ENOSPC; if (ebit < BITS_PER_LONG) { bitmap = (void *)((1UL << ebit) | RADIX_TREE_EXCEPTIONAL_ENTRY); radix_tree_iter_replace(root, &iter, slot, bitmap); *id = new; return 0; } bitmap = this_cpu_xchg(ida_bitmap, NULL); if (!bitmap) return -EAGAIN; memset(bitmap, 0, sizeof(*bitmap)); __set_bit(bit, bitmap->bitmap); radix_tree_iter_replace(root, &iter, slot, bitmap); } *id = new; return 0; } }


Matthew Wilcox37875.75%457.14%
Tejun Heo12124.25%342.86%

EXPORT_SYMBOL(ida_get_new_above); /** * ida_remove - Free the given ID * @ida: ida handle * @id: ID to free * * This function should not be called at the same time as ida_get_new_above(). */
void ida_remove(struct ida *ida, int id) { unsigned long index = id / IDA_BITMAP_BITS; unsigned offset = id % IDA_BITMAP_BITS; struct ida_bitmap *bitmap; unsigned long *btmp; struct radix_tree_iter iter; void __rcu **slot; slot = radix_tree_iter_lookup(&ida->ida_rt, &iter, index); if (!slot) goto err; bitmap = rcu_dereference_raw(*slot); if (radix_tree_exception(bitmap)) { btmp = (unsigned long *)slot; offset += RADIX_TREE_EXCEPTIONAL_SHIFT; if (offset >= BITS_PER_LONG) goto err; } else { btmp = bitmap->bitmap; } if (!test_bit(offset, btmp)) goto err; __clear_bit(offset, btmp); radix_tree_iter_tag_set(&ida->ida_rt, &iter, IDR_FREE); if (radix_tree_exception(bitmap)) { if (rcu_dereference_raw(*slot) == (void *)RADIX_TREE_EXCEPTIONAL_ENTRY) radix_tree_iter_delete(&ida->ida_rt, &iter, slot); } else if (bitmap_empty(btmp, IDA_BITMAP_BITS)) { kfree(bitmap); radix_tree_iter_delete(&ida->ida_rt, &iter, slot); } return; err: WARN(1, "ida_remove called for id=%d which is not allocated.\n", id); }


Matthew Wilcox13558.70%350.00%
Tejun Heo8938.70%116.67%
Jean Delvare31.30%116.67%
Lai Jiangshan31.30%116.67%

EXPORT_SYMBOL(ida_remove); /** * ida_destroy - Free the contents of an ida * @ida: ida handle * * Calling this function releases all resources associated with an IDA. When * this call returns, the IDA is empty and can be reused or freed. The caller * should not allow ida_remove() or ida_get_new_above() to be called at the * same time. */
void ida_destroy(struct ida *ida) { struct radix_tree_iter iter; void __rcu **slot; radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) { struct ida_bitmap *bitmap = rcu_dereference_raw(*slot); if (!radix_tree_exception(bitmap)) kfree(bitmap); radix_tree_iter_delete(&ida->ida_rt, &iter, slot); } }


Matthew Wilcox5376.81%375.00%
Tejun Heo1623.19%125.00%

EXPORT_SYMBOL(ida_destroy); /** * ida_simple_get - get a new id. * @ida: the (initialized) ida. * @start: the minimum id (inclusive, < 0x8000000) * @end: the maximum id (exclusive, < 0x8000000 or 0) * @gfp_mask: memory allocation flags * * Allocates an id in the range start <= id < end, or returns -ENOSPC. * On memory allocation failure, returns -ENOMEM. * * Compared to ida_get_new_above() this function does its own locking, and * should be used unless there are special requirements. * * Use ida_simple_remove() to get rid of an id. */
int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, gfp_t gfp_mask) { int ret, id; unsigned int max; unsigned long flags; BUG_ON((int)start < 0); BUG_ON((int)end < 0); if (end == 0) max = 0x80000000; else { BUG_ON(end < start); max = end - 1; } again: if (!ida_pre_get(ida, gfp_mask)) return -ENOMEM; spin_lock_irqsave(&simple_ida_lock, flags); ret = ida_get_new_above(ida, start, &id); if (!ret) { if (id > max) { ida_remove(ida, id); ret = -ENOSPC; } else { ret = id; } } spin_unlock_irqrestore(&simple_ida_lock, flags); if (unlikely(ret == -EAGAIN)) goto again; return ret; }


Rusty Russell16494.25%150.00%
Tejun Heo105.75%150.00%

EXPORT_SYMBOL(ida_simple_get); /** * ida_simple_remove - remove an allocated id. * @ida: the (initialized) ida. * @id: the id returned by ida_simple_get. * * Use to release an id allocated with ida_simple_get(). * * Compared to ida_remove() this function does its own locking, and should be * used unless there are special requirements. */
void ida_simple_remove(struct ida *ida, unsigned int id) { unsigned long flags; BUG_ON((int)id < 0); spin_lock_irqsave(&simple_ida_lock, flags); ida_remove(ida, id); spin_unlock_irqrestore(&simple_ida_lock, flags); }


Rusty Russell4180.39%150.00%
Tejun Heo1019.61%150.00%


Overall Contributors

Matthew Wilcox96158.92%413.79%
Tejun Heo32619.99%1034.48%
Rusty Russell22213.61%13.45%
George Anzinger382.33%13.45%
Jeff Mahoney372.27%13.45%
Andreas Gruenbacher191.16%13.45%
Kamezawa Hiroyuki70.43%13.45%
Lai Jiangshan60.37%26.90%
Ben Hutchings30.18%13.45%
Jean Delvare30.18%13.45%
Daniel Vetter20.12%13.45%
Manfred Spraul20.12%13.45%
Nadia Derbey20.12%13.45%
Paul Gortmaker10.06%13.45%
Sonny Rao10.06%13.45%
Roland Dreier10.06%13.45%
Directory: lib
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