Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/lib/idr.c b/lib/idr.c
index fab2fd5..c2cf2c5 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
#include <linux/bitmap.h>
#include <linux/bug.h>
#include <linux/export.h>
@@ -6,8 +7,6 @@
#include <linux/spinlock.h>
#include <linux/xarray.h>
-DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);
-
/**
* idr_alloc_u32() - Allocate an ID.
* @idr: IDR handle.
@@ -39,10 +38,8 @@
unsigned int base = idr->idr_base;
unsigned 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;
+ 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);
@@ -218,37 +215,6 @@
EXPORT_SYMBOL(idr_for_each);
/**
- * 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)
-{
- struct radix_tree_iter iter;
- void __rcu **slot;
- unsigned long base = idr->idr_base;
- unsigned long id = *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 = id;
- return rcu_dereference_raw(*slot);
-}
-EXPORT_SYMBOL(idr_get_next);
-
-/**
* idr_get_next_ul() - Find next populated entry.
* @idr: IDR handle.
* @nextid: Pointer to an ID.
@@ -262,20 +228,52 @@
{
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;
- slot = radix_tree_iter_find(&idr->idr_rt, &iter, id);
+ 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 rcu_dereference_raw(*slot);
+ 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.
@@ -295,15 +293,13 @@
void __rcu **slot = NULL;
void *entry;
- 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))
return ERR_PTR(-ENOENT);
- __radix_tree_replace(&idr->idr_rt, node, slot, ptr, NULL);
+ __radix_tree_replace(&idr->idr_rt, node, slot, ptr);
return entry;
}
@@ -324,6 +320,9 @@
* 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.
*/
@@ -331,190 +330,38 @@
/*
* 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.
+ * 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 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.
+ * 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 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.
+ * 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.
*
- * 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.
+ * 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 requires a lock to alloc/free. If we add a 'test_bit'
+ * 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.
*/
-#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1)
-
-static int ida_get_new_above(struct ida *ida, int start)
-{
- 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);
- return new + ebit -
- RADIX_TREE_EXCEPTIONAL_SHIFT;
- }
- bitmap = this_cpu_xchg(ida_bitmap, NULL);
- if (!bitmap)
- return -EAGAIN;
- 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);
- return new;
- }
- bitmap = this_cpu_xchg(ida_bitmap, NULL);
- if (!bitmap)
- return -EAGAIN;
- __set_bit(bit, bitmap->bitmap);
- radix_tree_iter_replace(root, &iter, slot, bitmap);
- }
-
- return new;
- }
-}
-
-static 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_free called for id=%d which is not allocated.\n", id);
-}
-
-/**
- * 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.
- */
-void ida_destroy(struct ida *ida)
-{
- unsigned long flags;
- struct radix_tree_iter iter;
- void __rcu **slot;
-
- xa_lock_irqsave(&ida->ida_rt, flags);
- 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);
- }
- xa_unlock_irqrestore(&ida->ida_rt, flags);
-}
-EXPORT_SYMBOL(ida_destroy);
-
/**
* ida_alloc_range() - Allocate an unused ID.
* @ida: IDA handle.
@@ -532,8 +379,10 @@
int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
gfp_t gfp)
{
- int id = 0;
+ 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;
@@ -541,22 +390,87 @@
if ((int)max < 0)
max = INT_MAX;
-again:
- xa_lock_irqsave(&ida->ida_rt, flags);
- id = ida_get_new_above(ida, min);
- if (id > (int)max) {
- ida_remove(ida, id);
- id = -ENOSPC;
- }
- xa_unlock_irqrestore(&ida->ida_rt, flags);
+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 (unlikely(id == -EAGAIN)) {
- if (!ida_pre_get(ida, gfp))
- return -ENOMEM;
- goto again;
+ 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;
+ }
}
- return id;
+ 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);
@@ -569,11 +483,112 @@
*/
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);
- xa_lock_irqsave(&ida->ida_rt, flags);
- ida_remove(ida, id);
- xa_unlock_irqrestore(&ida->ida_rt, flags);
+
+ 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.
+ */
+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