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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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);
     kfree(alloc);
     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;
 
     if ((int)id < 0)
         return;
 
     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

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