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63b1898fff
There is a race between xas_split() and xas_load() which can result in
the wrong page being returned, and thus data corruption. Fortunately,
it's hard to hit (syzbot took three months to find it) and often guarded
with VM_BUG_ON().
The anatomy of this race is:
thread A thread B
order-9 page is stored at index 0x200
lookup of page at index 0x274
page split starts
load of sibling entry at offset 9
stores nodes at offsets 8-15
load of entry at offset 8
The entry at offset 8 turns out to be a node, and so we descend into it,
and load the page at index 0x234 instead of 0x274. This is hard to fix
on the split side; we could replace the entire node that contains the
order-9 page instead of replacing the eight entries. Fixing it on
the lookup side is easier; just disallow sibling entries that point
to nodes. This cannot ever be a useful thing as the descent would not
know the correct offset to use within the new node.
The test suite continues to pass, but I have not added a new test for
this bug.
Reported-by: syzbot+cf4cf13056f85dec2c40@syzkaller.appspotmail.com
Tested-by: syzbot+cf4cf13056f85dec2c40@syzkaller.appspotmail.com
Fixes: 6b24ca4a1a
("mm: Use multi-index entries in the page cache")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2305 lines
59 KiB
C
2305 lines
59 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* XArray implementation
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* Copyright (c) 2017-2018 Microsoft Corporation
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* Copyright (c) 2018-2020 Oracle
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* Author: Matthew Wilcox <willy@infradead.org>
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*/
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#include <linux/bitmap.h>
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#include <linux/export.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <linux/xarray.h>
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/*
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* Coding conventions in this file:
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*
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* @xa is used to refer to the entire xarray.
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* @xas is the 'xarray operation state'. It may be either a pointer to
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* an xa_state, or an xa_state stored on the stack. This is an unfortunate
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* ambiguity.
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* @index is the index of the entry being operated on
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* @mark is an xa_mark_t; a small number indicating one of the mark bits.
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* @node refers to an xa_node; usually the primary one being operated on by
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* this function.
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* @offset is the index into the slots array inside an xa_node.
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* @parent refers to the @xa_node closer to the head than @node.
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* @entry refers to something stored in a slot in the xarray
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*/
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static inline unsigned int xa_lock_type(const struct xarray *xa)
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{
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return (__force unsigned int)xa->xa_flags & 3;
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}
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static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
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{
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if (lock_type == XA_LOCK_IRQ)
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xas_lock_irq(xas);
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else if (lock_type == XA_LOCK_BH)
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xas_lock_bh(xas);
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else
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xas_lock(xas);
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}
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static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
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{
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if (lock_type == XA_LOCK_IRQ)
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xas_unlock_irq(xas);
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else if (lock_type == XA_LOCK_BH)
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xas_unlock_bh(xas);
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else
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xas_unlock(xas);
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}
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static inline bool xa_track_free(const struct xarray *xa)
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{
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return xa->xa_flags & XA_FLAGS_TRACK_FREE;
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}
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static inline bool xa_zero_busy(const struct xarray *xa)
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{
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return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
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}
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static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
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{
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if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
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xa->xa_flags |= XA_FLAGS_MARK(mark);
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}
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static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
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{
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if (xa->xa_flags & XA_FLAGS_MARK(mark))
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xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
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}
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static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
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{
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return node->marks[(__force unsigned)mark];
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}
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static inline bool node_get_mark(struct xa_node *node,
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unsigned int offset, xa_mark_t mark)
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{
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return test_bit(offset, node_marks(node, mark));
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}
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/* returns true if the bit was set */
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static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
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xa_mark_t mark)
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{
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return __test_and_set_bit(offset, node_marks(node, mark));
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}
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/* returns true if the bit was set */
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static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
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xa_mark_t mark)
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{
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return __test_and_clear_bit(offset, node_marks(node, mark));
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}
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static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
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{
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return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
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}
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static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
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{
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bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
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}
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#define mark_inc(mark) do { \
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mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
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} while (0)
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/*
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* xas_squash_marks() - Merge all marks to the first entry
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* @xas: Array operation state.
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*
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* Set a mark on the first entry if any entry has it set. Clear marks on
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* all sibling entries.
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*/
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static void xas_squash_marks(const struct xa_state *xas)
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{
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unsigned int mark = 0;
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unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
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if (!xas->xa_sibs)
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return;
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do {
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unsigned long *marks = xas->xa_node->marks[mark];
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if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
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continue;
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__set_bit(xas->xa_offset, marks);
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bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
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} while (mark++ != (__force unsigned)XA_MARK_MAX);
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}
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/* extracts the offset within this node from the index */
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static unsigned int get_offset(unsigned long index, struct xa_node *node)
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{
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return (index >> node->shift) & XA_CHUNK_MASK;
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}
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static void xas_set_offset(struct xa_state *xas)
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{
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xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
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}
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/* move the index either forwards (find) or backwards (sibling slot) */
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static void xas_move_index(struct xa_state *xas, unsigned long offset)
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{
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unsigned int shift = xas->xa_node->shift;
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xas->xa_index &= ~XA_CHUNK_MASK << shift;
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xas->xa_index += offset << shift;
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}
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static void xas_next_offset(struct xa_state *xas)
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{
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xas->xa_offset++;
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xas_move_index(xas, xas->xa_offset);
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}
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static void *set_bounds(struct xa_state *xas)
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{
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xas->xa_node = XAS_BOUNDS;
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return NULL;
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}
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/*
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* Starts a walk. If the @xas is already valid, we assume that it's on
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* the right path and just return where we've got to. If we're in an
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* error state, return NULL. If the index is outside the current scope
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* of the xarray, return NULL without changing @xas->xa_node. Otherwise
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* set @xas->xa_node to NULL and return the current head of the array.
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*/
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static void *xas_start(struct xa_state *xas)
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{
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void *entry;
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if (xas_valid(xas))
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return xas_reload(xas);
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if (xas_error(xas))
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return NULL;
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entry = xa_head(xas->xa);
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if (!xa_is_node(entry)) {
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if (xas->xa_index)
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return set_bounds(xas);
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} else {
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if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
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return set_bounds(xas);
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}
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xas->xa_node = NULL;
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return entry;
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}
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static void *xas_descend(struct xa_state *xas, struct xa_node *node)
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{
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unsigned int offset = get_offset(xas->xa_index, node);
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void *entry = xa_entry(xas->xa, node, offset);
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xas->xa_node = node;
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if (xa_is_sibling(entry)) {
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offset = xa_to_sibling(entry);
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entry = xa_entry(xas->xa, node, offset);
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if (node->shift && xa_is_node(entry))
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entry = XA_RETRY_ENTRY;
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}
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xas->xa_offset = offset;
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return entry;
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}
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/**
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* xas_load() - Load an entry from the XArray (advanced).
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* @xas: XArray operation state.
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*
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* Usually walks the @xas to the appropriate state to load the entry
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* stored at xa_index. However, it will do nothing and return %NULL if
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* @xas is in an error state. xas_load() will never expand the tree.
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*
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* If the xa_state is set up to operate on a multi-index entry, xas_load()
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* may return %NULL or an internal entry, even if there are entries
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* present within the range specified by @xas.
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*
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* Context: Any context. The caller should hold the xa_lock or the RCU lock.
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* Return: Usually an entry in the XArray, but see description for exceptions.
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*/
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void *xas_load(struct xa_state *xas)
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{
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void *entry = xas_start(xas);
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while (xa_is_node(entry)) {
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struct xa_node *node = xa_to_node(entry);
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if (xas->xa_shift > node->shift)
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break;
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entry = xas_descend(xas, node);
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if (node->shift == 0)
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break;
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}
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return entry;
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}
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EXPORT_SYMBOL_GPL(xas_load);
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/* Move the radix tree node cache here */
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extern struct kmem_cache *radix_tree_node_cachep;
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extern void radix_tree_node_rcu_free(struct rcu_head *head);
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#define XA_RCU_FREE ((struct xarray *)1)
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static void xa_node_free(struct xa_node *node)
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{
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XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
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node->array = XA_RCU_FREE;
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call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
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}
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/*
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* xas_destroy() - Free any resources allocated during the XArray operation.
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* @xas: XArray operation state.
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*
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* This function is now internal-only.
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*/
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static void xas_destroy(struct xa_state *xas)
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{
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struct xa_node *next, *node = xas->xa_alloc;
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while (node) {
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XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
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next = rcu_dereference_raw(node->parent);
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radix_tree_node_rcu_free(&node->rcu_head);
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xas->xa_alloc = node = next;
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}
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}
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/**
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* xas_nomem() - Allocate memory if needed.
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* @xas: XArray operation state.
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* @gfp: Memory allocation flags.
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*
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* If we need to add new nodes to the XArray, we try to allocate memory
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* with GFP_NOWAIT while holding the lock, which will usually succeed.
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* If it fails, @xas is flagged as needing memory to continue. The caller
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* should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
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* the caller should retry the operation.
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*
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* Forward progress is guaranteed as one node is allocated here and
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* stored in the xa_state where it will be found by xas_alloc(). More
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* nodes will likely be found in the slab allocator, but we do not tie
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* them up here.
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*
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* Return: true if memory was needed, and was successfully allocated.
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*/
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bool xas_nomem(struct xa_state *xas, gfp_t gfp)
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{
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if (xas->xa_node != XA_ERROR(-ENOMEM)) {
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xas_destroy(xas);
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return false;
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}
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if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
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gfp |= __GFP_ACCOUNT;
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xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
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if (!xas->xa_alloc)
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return false;
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xas->xa_alloc->parent = NULL;
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XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
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xas->xa_node = XAS_RESTART;
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return true;
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}
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EXPORT_SYMBOL_GPL(xas_nomem);
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/*
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* __xas_nomem() - Drop locks and allocate memory if needed.
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* @xas: XArray operation state.
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* @gfp: Memory allocation flags.
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*
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* Internal variant of xas_nomem().
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*
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* Return: true if memory was needed, and was successfully allocated.
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*/
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static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
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__must_hold(xas->xa->xa_lock)
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{
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unsigned int lock_type = xa_lock_type(xas->xa);
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if (xas->xa_node != XA_ERROR(-ENOMEM)) {
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xas_destroy(xas);
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return false;
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}
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if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
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gfp |= __GFP_ACCOUNT;
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if (gfpflags_allow_blocking(gfp)) {
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xas_unlock_type(xas, lock_type);
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xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
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xas_lock_type(xas, lock_type);
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} else {
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xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
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}
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if (!xas->xa_alloc)
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return false;
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xas->xa_alloc->parent = NULL;
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XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
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xas->xa_node = XAS_RESTART;
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return true;
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}
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static void xas_update(struct xa_state *xas, struct xa_node *node)
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{
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if (xas->xa_update)
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xas->xa_update(node);
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else
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XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
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}
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static void *xas_alloc(struct xa_state *xas, unsigned int shift)
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{
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struct xa_node *parent = xas->xa_node;
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struct xa_node *node = xas->xa_alloc;
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if (xas_invalid(xas))
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return NULL;
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if (node) {
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xas->xa_alloc = NULL;
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} else {
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gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
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if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
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gfp |= __GFP_ACCOUNT;
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node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
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if (!node) {
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xas_set_err(xas, -ENOMEM);
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return NULL;
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}
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}
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if (parent) {
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node->offset = xas->xa_offset;
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parent->count++;
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XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
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xas_update(xas, parent);
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}
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XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
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XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
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node->shift = shift;
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node->count = 0;
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node->nr_values = 0;
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RCU_INIT_POINTER(node->parent, xas->xa_node);
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node->array = xas->xa;
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return node;
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}
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#ifdef CONFIG_XARRAY_MULTI
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/* Returns the number of indices covered by a given xa_state */
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static unsigned long xas_size(const struct xa_state *xas)
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{
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return (xas->xa_sibs + 1UL) << xas->xa_shift;
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}
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#endif
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/*
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* Use this to calculate the maximum index that will need to be created
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* in order to add the entry described by @xas. Because we cannot store a
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* multi-index entry at index 0, the calculation is a little more complex
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* than you might expect.
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*/
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static unsigned long xas_max(struct xa_state *xas)
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{
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unsigned long max = xas->xa_index;
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#ifdef CONFIG_XARRAY_MULTI
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if (xas->xa_shift || xas->xa_sibs) {
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unsigned long mask = xas_size(xas) - 1;
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max |= mask;
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if (mask == max)
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max++;
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}
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#endif
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return max;
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}
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/* The maximum index that can be contained in the array without expanding it */
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static unsigned long max_index(void *entry)
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{
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if (!xa_is_node(entry))
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return 0;
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return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
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}
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static void xas_shrink(struct xa_state *xas)
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{
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struct xarray *xa = xas->xa;
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struct xa_node *node = xas->xa_node;
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for (;;) {
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void *entry;
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XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
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if (node->count != 1)
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break;
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entry = xa_entry_locked(xa, node, 0);
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if (!entry)
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break;
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if (!xa_is_node(entry) && node->shift)
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break;
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if (xa_is_zero(entry) && xa_zero_busy(xa))
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entry = NULL;
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xas->xa_node = XAS_BOUNDS;
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RCU_INIT_POINTER(xa->xa_head, entry);
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if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
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xa_mark_clear(xa, XA_FREE_MARK);
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node->count = 0;
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node->nr_values = 0;
|
|
if (!xa_is_node(entry))
|
|
RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
|
|
xas_update(xas, node);
|
|
xa_node_free(node);
|
|
if (!xa_is_node(entry))
|
|
break;
|
|
node = xa_to_node(entry);
|
|
node->parent = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* xas_delete_node() - Attempt to delete an xa_node
|
|
* @xas: Array operation state.
|
|
*
|
|
* Attempts to delete the @xas->xa_node. This will fail if xa->node has
|
|
* a non-zero reference count.
|
|
*/
|
|
static void xas_delete_node(struct xa_state *xas)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
|
|
for (;;) {
|
|
struct xa_node *parent;
|
|
|
|
XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
|
|
if (node->count)
|
|
break;
|
|
|
|
parent = xa_parent_locked(xas->xa, node);
|
|
xas->xa_node = parent;
|
|
xas->xa_offset = node->offset;
|
|
xa_node_free(node);
|
|
|
|
if (!parent) {
|
|
xas->xa->xa_head = NULL;
|
|
xas->xa_node = XAS_BOUNDS;
|
|
return;
|
|
}
|
|
|
|
parent->slots[xas->xa_offset] = NULL;
|
|
parent->count--;
|
|
XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
|
|
node = parent;
|
|
xas_update(xas, node);
|
|
}
|
|
|
|
if (!node->parent)
|
|
xas_shrink(xas);
|
|
}
|
|
|
|
/**
|
|
* xas_free_nodes() - Free this node and all nodes that it references
|
|
* @xas: Array operation state.
|
|
* @top: Node to free
|
|
*
|
|
* This node has been removed from the tree. We must now free it and all
|
|
* of its subnodes. There may be RCU walkers with references into the tree,
|
|
* so we must replace all entries with retry markers.
|
|
*/
|
|
static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
|
|
{
|
|
unsigned int offset = 0;
|
|
struct xa_node *node = top;
|
|
|
|
for (;;) {
|
|
void *entry = xa_entry_locked(xas->xa, node, offset);
|
|
|
|
if (node->shift && xa_is_node(entry)) {
|
|
node = xa_to_node(entry);
|
|
offset = 0;
|
|
continue;
|
|
}
|
|
if (entry)
|
|
RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
|
|
offset++;
|
|
while (offset == XA_CHUNK_SIZE) {
|
|
struct xa_node *parent;
|
|
|
|
parent = xa_parent_locked(xas->xa, node);
|
|
offset = node->offset + 1;
|
|
node->count = 0;
|
|
node->nr_values = 0;
|
|
xas_update(xas, node);
|
|
xa_node_free(node);
|
|
if (node == top)
|
|
return;
|
|
node = parent;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* xas_expand adds nodes to the head of the tree until it has reached
|
|
* sufficient height to be able to contain @xas->xa_index
|
|
*/
|
|
static int xas_expand(struct xa_state *xas, void *head)
|
|
{
|
|
struct xarray *xa = xas->xa;
|
|
struct xa_node *node = NULL;
|
|
unsigned int shift = 0;
|
|
unsigned long max = xas_max(xas);
|
|
|
|
if (!head) {
|
|
if (max == 0)
|
|
return 0;
|
|
while ((max >> shift) >= XA_CHUNK_SIZE)
|
|
shift += XA_CHUNK_SHIFT;
|
|
return shift + XA_CHUNK_SHIFT;
|
|
} else if (xa_is_node(head)) {
|
|
node = xa_to_node(head);
|
|
shift = node->shift + XA_CHUNK_SHIFT;
|
|
}
|
|
xas->xa_node = NULL;
|
|
|
|
while (max > max_index(head)) {
|
|
xa_mark_t mark = 0;
|
|
|
|
XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
|
|
node = xas_alloc(xas, shift);
|
|
if (!node)
|
|
return -ENOMEM;
|
|
|
|
node->count = 1;
|
|
if (xa_is_value(head))
|
|
node->nr_values = 1;
|
|
RCU_INIT_POINTER(node->slots[0], head);
|
|
|
|
/* Propagate the aggregated mark info to the new child */
|
|
for (;;) {
|
|
if (xa_track_free(xa) && mark == XA_FREE_MARK) {
|
|
node_mark_all(node, XA_FREE_MARK);
|
|
if (!xa_marked(xa, XA_FREE_MARK)) {
|
|
node_clear_mark(node, 0, XA_FREE_MARK);
|
|
xa_mark_set(xa, XA_FREE_MARK);
|
|
}
|
|
} else if (xa_marked(xa, mark)) {
|
|
node_set_mark(node, 0, mark);
|
|
}
|
|
if (mark == XA_MARK_MAX)
|
|
break;
|
|
mark_inc(mark);
|
|
}
|
|
|
|
/*
|
|
* Now that the new node is fully initialised, we can add
|
|
* it to the tree
|
|
*/
|
|
if (xa_is_node(head)) {
|
|
xa_to_node(head)->offset = 0;
|
|
rcu_assign_pointer(xa_to_node(head)->parent, node);
|
|
}
|
|
head = xa_mk_node(node);
|
|
rcu_assign_pointer(xa->xa_head, head);
|
|
xas_update(xas, node);
|
|
|
|
shift += XA_CHUNK_SHIFT;
|
|
}
|
|
|
|
xas->xa_node = node;
|
|
return shift;
|
|
}
|
|
|
|
/*
|
|
* xas_create() - Create a slot to store an entry in.
|
|
* @xas: XArray operation state.
|
|
* @allow_root: %true if we can store the entry in the root directly
|
|
*
|
|
* Most users will not need to call this function directly, as it is called
|
|
* by xas_store(). It is useful for doing conditional store operations
|
|
* (see the xa_cmpxchg() implementation for an example).
|
|
*
|
|
* Return: If the slot already existed, returns the contents of this slot.
|
|
* If the slot was newly created, returns %NULL. If it failed to create the
|
|
* slot, returns %NULL and indicates the error in @xas.
|
|
*/
|
|
static void *xas_create(struct xa_state *xas, bool allow_root)
|
|
{
|
|
struct xarray *xa = xas->xa;
|
|
void *entry;
|
|
void __rcu **slot;
|
|
struct xa_node *node = xas->xa_node;
|
|
int shift;
|
|
unsigned int order = xas->xa_shift;
|
|
|
|
if (xas_top(node)) {
|
|
entry = xa_head_locked(xa);
|
|
xas->xa_node = NULL;
|
|
if (!entry && xa_zero_busy(xa))
|
|
entry = XA_ZERO_ENTRY;
|
|
shift = xas_expand(xas, entry);
|
|
if (shift < 0)
|
|
return NULL;
|
|
if (!shift && !allow_root)
|
|
shift = XA_CHUNK_SHIFT;
|
|
entry = xa_head_locked(xa);
|
|
slot = &xa->xa_head;
|
|
} else if (xas_error(xas)) {
|
|
return NULL;
|
|
} else if (node) {
|
|
unsigned int offset = xas->xa_offset;
|
|
|
|
shift = node->shift;
|
|
entry = xa_entry_locked(xa, node, offset);
|
|
slot = &node->slots[offset];
|
|
} else {
|
|
shift = 0;
|
|
entry = xa_head_locked(xa);
|
|
slot = &xa->xa_head;
|
|
}
|
|
|
|
while (shift > order) {
|
|
shift -= XA_CHUNK_SHIFT;
|
|
if (!entry) {
|
|
node = xas_alloc(xas, shift);
|
|
if (!node)
|
|
break;
|
|
if (xa_track_free(xa))
|
|
node_mark_all(node, XA_FREE_MARK);
|
|
rcu_assign_pointer(*slot, xa_mk_node(node));
|
|
} else if (xa_is_node(entry)) {
|
|
node = xa_to_node(entry);
|
|
} else {
|
|
break;
|
|
}
|
|
entry = xas_descend(xas, node);
|
|
slot = &node->slots[xas->xa_offset];
|
|
}
|
|
|
|
return entry;
|
|
}
|
|
|
|
/**
|
|
* xas_create_range() - Ensure that stores to this range will succeed
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Creates all of the slots in the range covered by @xas. Sets @xas to
|
|
* create single-index entries and positions it at the beginning of the
|
|
* range. This is for the benefit of users which have not yet been
|
|
* converted to use multi-index entries.
|
|
*/
|
|
void xas_create_range(struct xa_state *xas)
|
|
{
|
|
unsigned long index = xas->xa_index;
|
|
unsigned char shift = xas->xa_shift;
|
|
unsigned char sibs = xas->xa_sibs;
|
|
|
|
xas->xa_index |= ((sibs + 1UL) << shift) - 1;
|
|
if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
|
|
xas->xa_offset |= sibs;
|
|
xas->xa_shift = 0;
|
|
xas->xa_sibs = 0;
|
|
|
|
for (;;) {
|
|
xas_create(xas, true);
|
|
if (xas_error(xas))
|
|
goto restore;
|
|
if (xas->xa_index <= (index | XA_CHUNK_MASK))
|
|
goto success;
|
|
xas->xa_index -= XA_CHUNK_SIZE;
|
|
|
|
for (;;) {
|
|
struct xa_node *node = xas->xa_node;
|
|
if (node->shift >= shift)
|
|
break;
|
|
xas->xa_node = xa_parent_locked(xas->xa, node);
|
|
xas->xa_offset = node->offset - 1;
|
|
if (node->offset != 0)
|
|
break;
|
|
}
|
|
}
|
|
|
|
restore:
|
|
xas->xa_shift = shift;
|
|
xas->xa_sibs = sibs;
|
|
xas->xa_index = index;
|
|
return;
|
|
success:
|
|
xas->xa_index = index;
|
|
if (xas->xa_node)
|
|
xas_set_offset(xas);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_create_range);
|
|
|
|
static void update_node(struct xa_state *xas, struct xa_node *node,
|
|
int count, int values)
|
|
{
|
|
if (!node || (!count && !values))
|
|
return;
|
|
|
|
node->count += count;
|
|
node->nr_values += values;
|
|
XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
|
|
XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
|
|
xas_update(xas, node);
|
|
if (count < 0)
|
|
xas_delete_node(xas);
|
|
}
|
|
|
|
/**
|
|
* xas_store() - Store this entry in the XArray.
|
|
* @xas: XArray operation state.
|
|
* @entry: New entry.
|
|
*
|
|
* If @xas is operating on a multi-index entry, the entry returned by this
|
|
* function is essentially meaningless (it may be an internal entry or it
|
|
* may be %NULL, even if there are non-NULL entries at some of the indices
|
|
* covered by the range). This is not a problem for any current users,
|
|
* and can be changed if needed.
|
|
*
|
|
* Return: The old entry at this index.
|
|
*/
|
|
void *xas_store(struct xa_state *xas, void *entry)
|
|
{
|
|
struct xa_node *node;
|
|
void __rcu **slot = &xas->xa->xa_head;
|
|
unsigned int offset, max;
|
|
int count = 0;
|
|
int values = 0;
|
|
void *first, *next;
|
|
bool value = xa_is_value(entry);
|
|
|
|
if (entry) {
|
|
bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
|
|
first = xas_create(xas, allow_root);
|
|
} else {
|
|
first = xas_load(xas);
|
|
}
|
|
|
|
if (xas_invalid(xas))
|
|
return first;
|
|
node = xas->xa_node;
|
|
if (node && (xas->xa_shift < node->shift))
|
|
xas->xa_sibs = 0;
|
|
if ((first == entry) && !xas->xa_sibs)
|
|
return first;
|
|
|
|
next = first;
|
|
offset = xas->xa_offset;
|
|
max = xas->xa_offset + xas->xa_sibs;
|
|
if (node) {
|
|
slot = &node->slots[offset];
|
|
if (xas->xa_sibs)
|
|
xas_squash_marks(xas);
|
|
}
|
|
if (!entry)
|
|
xas_init_marks(xas);
|
|
|
|
for (;;) {
|
|
/*
|
|
* Must clear the marks before setting the entry to NULL,
|
|
* otherwise xas_for_each_marked may find a NULL entry and
|
|
* stop early. rcu_assign_pointer contains a release barrier
|
|
* so the mark clearing will appear to happen before the
|
|
* entry is set to NULL.
|
|
*/
|
|
rcu_assign_pointer(*slot, entry);
|
|
if (xa_is_node(next) && (!node || node->shift))
|
|
xas_free_nodes(xas, xa_to_node(next));
|
|
if (!node)
|
|
break;
|
|
count += !next - !entry;
|
|
values += !xa_is_value(first) - !value;
|
|
if (entry) {
|
|
if (offset == max)
|
|
break;
|
|
if (!xa_is_sibling(entry))
|
|
entry = xa_mk_sibling(xas->xa_offset);
|
|
} else {
|
|
if (offset == XA_CHUNK_MASK)
|
|
break;
|
|
}
|
|
next = xa_entry_locked(xas->xa, node, ++offset);
|
|
if (!xa_is_sibling(next)) {
|
|
if (!entry && (offset > max))
|
|
break;
|
|
first = next;
|
|
}
|
|
slot++;
|
|
}
|
|
|
|
update_node(xas, node, count, values);
|
|
return first;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_store);
|
|
|
|
/**
|
|
* xas_get_mark() - Returns the state of this mark.
|
|
* @xas: XArray operation state.
|
|
* @mark: Mark number.
|
|
*
|
|
* Return: true if the mark is set, false if the mark is clear or @xas
|
|
* is in an error state.
|
|
*/
|
|
bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
|
|
{
|
|
if (xas_invalid(xas))
|
|
return false;
|
|
if (!xas->xa_node)
|
|
return xa_marked(xas->xa, mark);
|
|
return node_get_mark(xas->xa_node, xas->xa_offset, mark);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_get_mark);
|
|
|
|
/**
|
|
* xas_set_mark() - Sets the mark on this entry and its parents.
|
|
* @xas: XArray operation state.
|
|
* @mark: Mark number.
|
|
*
|
|
* Sets the specified mark on this entry, and walks up the tree setting it
|
|
* on all the ancestor entries. Does nothing if @xas has not been walked to
|
|
* an entry, or is in an error state.
|
|
*/
|
|
void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
unsigned int offset = xas->xa_offset;
|
|
|
|
if (xas_invalid(xas))
|
|
return;
|
|
|
|
while (node) {
|
|
if (node_set_mark(node, offset, mark))
|
|
return;
|
|
offset = node->offset;
|
|
node = xa_parent_locked(xas->xa, node);
|
|
}
|
|
|
|
if (!xa_marked(xas->xa, mark))
|
|
xa_mark_set(xas->xa, mark);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_set_mark);
|
|
|
|
/**
|
|
* xas_clear_mark() - Clears the mark on this entry and its parents.
|
|
* @xas: XArray operation state.
|
|
* @mark: Mark number.
|
|
*
|
|
* Clears the specified mark on this entry, and walks back to the head
|
|
* attempting to clear it on all the ancestor entries. Does nothing if
|
|
* @xas has not been walked to an entry, or is in an error state.
|
|
*/
|
|
void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
unsigned int offset = xas->xa_offset;
|
|
|
|
if (xas_invalid(xas))
|
|
return;
|
|
|
|
while (node) {
|
|
if (!node_clear_mark(node, offset, mark))
|
|
return;
|
|
if (node_any_mark(node, mark))
|
|
return;
|
|
|
|
offset = node->offset;
|
|
node = xa_parent_locked(xas->xa, node);
|
|
}
|
|
|
|
if (xa_marked(xas->xa, mark))
|
|
xa_mark_clear(xas->xa, mark);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_clear_mark);
|
|
|
|
/**
|
|
* xas_init_marks() - Initialise all marks for the entry
|
|
* @xas: Array operations state.
|
|
*
|
|
* Initialise all marks for the entry specified by @xas. If we're tracking
|
|
* free entries with a mark, we need to set it on all entries. All other
|
|
* marks are cleared.
|
|
*
|
|
* This implementation is not as efficient as it could be; we may walk
|
|
* up the tree multiple times.
|
|
*/
|
|
void xas_init_marks(const struct xa_state *xas)
|
|
{
|
|
xa_mark_t mark = 0;
|
|
|
|
for (;;) {
|
|
if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
|
|
xas_set_mark(xas, mark);
|
|
else
|
|
xas_clear_mark(xas, mark);
|
|
if (mark == XA_MARK_MAX)
|
|
break;
|
|
mark_inc(mark);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_init_marks);
|
|
|
|
#ifdef CONFIG_XARRAY_MULTI
|
|
static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
|
|
{
|
|
unsigned int marks = 0;
|
|
xa_mark_t mark = XA_MARK_0;
|
|
|
|
for (;;) {
|
|
if (node_get_mark(node, offset, mark))
|
|
marks |= 1 << (__force unsigned int)mark;
|
|
if (mark == XA_MARK_MAX)
|
|
break;
|
|
mark_inc(mark);
|
|
}
|
|
|
|
return marks;
|
|
}
|
|
|
|
static void node_set_marks(struct xa_node *node, unsigned int offset,
|
|
struct xa_node *child, unsigned int marks)
|
|
{
|
|
xa_mark_t mark = XA_MARK_0;
|
|
|
|
for (;;) {
|
|
if (marks & (1 << (__force unsigned int)mark)) {
|
|
node_set_mark(node, offset, mark);
|
|
if (child)
|
|
node_mark_all(child, mark);
|
|
}
|
|
if (mark == XA_MARK_MAX)
|
|
break;
|
|
mark_inc(mark);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* xas_split_alloc() - Allocate memory for splitting an entry.
|
|
* @xas: XArray operation state.
|
|
* @entry: New entry which will be stored in the array.
|
|
* @order: Current entry order.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* This function should be called before calling xas_split().
|
|
* If necessary, it will allocate new nodes (and fill them with @entry)
|
|
* to prepare for the upcoming split of an entry of @order size into
|
|
* entries of the order stored in the @xas.
|
|
*
|
|
* Context: May sleep if @gfp flags permit.
|
|
*/
|
|
void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
|
|
gfp_t gfp)
|
|
{
|
|
unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
|
|
unsigned int mask = xas->xa_sibs;
|
|
|
|
/* XXX: no support for splitting really large entries yet */
|
|
if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
|
|
goto nomem;
|
|
if (xas->xa_shift + XA_CHUNK_SHIFT > order)
|
|
return;
|
|
|
|
do {
|
|
unsigned int i;
|
|
void *sibling = NULL;
|
|
struct xa_node *node;
|
|
|
|
node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
|
|
if (!node)
|
|
goto nomem;
|
|
node->array = xas->xa;
|
|
for (i = 0; i < XA_CHUNK_SIZE; i++) {
|
|
if ((i & mask) == 0) {
|
|
RCU_INIT_POINTER(node->slots[i], entry);
|
|
sibling = xa_mk_sibling(i);
|
|
} else {
|
|
RCU_INIT_POINTER(node->slots[i], sibling);
|
|
}
|
|
}
|
|
RCU_INIT_POINTER(node->parent, xas->xa_alloc);
|
|
xas->xa_alloc = node;
|
|
} while (sibs-- > 0);
|
|
|
|
return;
|
|
nomem:
|
|
xas_destroy(xas);
|
|
xas_set_err(xas, -ENOMEM);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_split_alloc);
|
|
|
|
/**
|
|
* xas_split() - Split a multi-index entry into smaller entries.
|
|
* @xas: XArray operation state.
|
|
* @entry: New entry to store in the array.
|
|
* @order: Current entry order.
|
|
*
|
|
* The size of the new entries is set in @xas. The value in @entry is
|
|
* copied to all the replacement entries.
|
|
*
|
|
* Context: Any context. The caller should hold the xa_lock.
|
|
*/
|
|
void xas_split(struct xa_state *xas, void *entry, unsigned int order)
|
|
{
|
|
unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
|
|
unsigned int offset, marks;
|
|
struct xa_node *node;
|
|
void *curr = xas_load(xas);
|
|
int values = 0;
|
|
|
|
node = xas->xa_node;
|
|
if (xas_top(node))
|
|
return;
|
|
|
|
marks = node_get_marks(node, xas->xa_offset);
|
|
|
|
offset = xas->xa_offset + sibs;
|
|
do {
|
|
if (xas->xa_shift < node->shift) {
|
|
struct xa_node *child = xas->xa_alloc;
|
|
|
|
xas->xa_alloc = rcu_dereference_raw(child->parent);
|
|
child->shift = node->shift - XA_CHUNK_SHIFT;
|
|
child->offset = offset;
|
|
child->count = XA_CHUNK_SIZE;
|
|
child->nr_values = xa_is_value(entry) ?
|
|
XA_CHUNK_SIZE : 0;
|
|
RCU_INIT_POINTER(child->parent, node);
|
|
node_set_marks(node, offset, child, marks);
|
|
rcu_assign_pointer(node->slots[offset],
|
|
xa_mk_node(child));
|
|
if (xa_is_value(curr))
|
|
values--;
|
|
xas_update(xas, child);
|
|
} else {
|
|
unsigned int canon = offset - xas->xa_sibs;
|
|
|
|
node_set_marks(node, canon, NULL, marks);
|
|
rcu_assign_pointer(node->slots[canon], entry);
|
|
while (offset > canon)
|
|
rcu_assign_pointer(node->slots[offset--],
|
|
xa_mk_sibling(canon));
|
|
values += (xa_is_value(entry) - xa_is_value(curr)) *
|
|
(xas->xa_sibs + 1);
|
|
}
|
|
} while (offset-- > xas->xa_offset);
|
|
|
|
node->nr_values += values;
|
|
xas_update(xas, node);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_split);
|
|
#endif
|
|
|
|
/**
|
|
* xas_pause() - Pause a walk to drop a lock.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Some users need to pause a walk and drop the lock they're holding in
|
|
* order to yield to a higher priority thread or carry out an operation
|
|
* on an entry. Those users should call this function before they drop
|
|
* the lock. It resets the @xas to be suitable for the next iteration
|
|
* of the loop after the user has reacquired the lock. If most entries
|
|
* found during a walk require you to call xas_pause(), the xa_for_each()
|
|
* iterator may be more appropriate.
|
|
*
|
|
* Note that xas_pause() only works for forward iteration. If a user needs
|
|
* to pause a reverse iteration, we will need a xas_pause_rev().
|
|
*/
|
|
void xas_pause(struct xa_state *xas)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
|
|
if (xas_invalid(xas))
|
|
return;
|
|
|
|
xas->xa_node = XAS_RESTART;
|
|
if (node) {
|
|
unsigned long offset = xas->xa_offset;
|
|
while (++offset < XA_CHUNK_SIZE) {
|
|
if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
|
|
break;
|
|
}
|
|
xas->xa_index += (offset - xas->xa_offset) << node->shift;
|
|
if (xas->xa_index == 0)
|
|
xas->xa_node = XAS_BOUNDS;
|
|
} else {
|
|
xas->xa_index++;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_pause);
|
|
|
|
/*
|
|
* __xas_prev() - Find the previous entry in the XArray.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Helper function for xas_prev() which handles all the complex cases
|
|
* out of line.
|
|
*/
|
|
void *__xas_prev(struct xa_state *xas)
|
|
{
|
|
void *entry;
|
|
|
|
if (!xas_frozen(xas->xa_node))
|
|
xas->xa_index--;
|
|
if (!xas->xa_node)
|
|
return set_bounds(xas);
|
|
if (xas_not_node(xas->xa_node))
|
|
return xas_load(xas);
|
|
|
|
if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
|
|
xas->xa_offset--;
|
|
|
|
while (xas->xa_offset == 255) {
|
|
xas->xa_offset = xas->xa_node->offset - 1;
|
|
xas->xa_node = xa_parent(xas->xa, xas->xa_node);
|
|
if (!xas->xa_node)
|
|
return set_bounds(xas);
|
|
}
|
|
|
|
for (;;) {
|
|
entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
|
|
if (!xa_is_node(entry))
|
|
return entry;
|
|
|
|
xas->xa_node = xa_to_node(entry);
|
|
xas_set_offset(xas);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(__xas_prev);
|
|
|
|
/*
|
|
* __xas_next() - Find the next entry in the XArray.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Helper function for xas_next() which handles all the complex cases
|
|
* out of line.
|
|
*/
|
|
void *__xas_next(struct xa_state *xas)
|
|
{
|
|
void *entry;
|
|
|
|
if (!xas_frozen(xas->xa_node))
|
|
xas->xa_index++;
|
|
if (!xas->xa_node)
|
|
return set_bounds(xas);
|
|
if (xas_not_node(xas->xa_node))
|
|
return xas_load(xas);
|
|
|
|
if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
|
|
xas->xa_offset++;
|
|
|
|
while (xas->xa_offset == XA_CHUNK_SIZE) {
|
|
xas->xa_offset = xas->xa_node->offset + 1;
|
|
xas->xa_node = xa_parent(xas->xa, xas->xa_node);
|
|
if (!xas->xa_node)
|
|
return set_bounds(xas);
|
|
}
|
|
|
|
for (;;) {
|
|
entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
|
|
if (!xa_is_node(entry))
|
|
return entry;
|
|
|
|
xas->xa_node = xa_to_node(entry);
|
|
xas_set_offset(xas);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(__xas_next);
|
|
|
|
/**
|
|
* xas_find() - Find the next present entry in the XArray.
|
|
* @xas: XArray operation state.
|
|
* @max: Highest index to return.
|
|
*
|
|
* If the @xas has not yet been walked to an entry, return the entry
|
|
* which has an index >= xas.xa_index. If it has been walked, the entry
|
|
* currently being pointed at has been processed, and so we move to the
|
|
* next entry.
|
|
*
|
|
* If no entry is found and the array is smaller than @max, the iterator
|
|
* is set to the smallest index not yet in the array. This allows @xas
|
|
* to be immediately passed to xas_store().
|
|
*
|
|
* Return: The entry, if found, otherwise %NULL.
|
|
*/
|
|
void *xas_find(struct xa_state *xas, unsigned long max)
|
|
{
|
|
void *entry;
|
|
|
|
if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
|
|
return NULL;
|
|
if (xas->xa_index > max)
|
|
return set_bounds(xas);
|
|
|
|
if (!xas->xa_node) {
|
|
xas->xa_index = 1;
|
|
return set_bounds(xas);
|
|
} else if (xas->xa_node == XAS_RESTART) {
|
|
entry = xas_load(xas);
|
|
if (entry || xas_not_node(xas->xa_node))
|
|
return entry;
|
|
} else if (!xas->xa_node->shift &&
|
|
xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
|
|
xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
|
|
}
|
|
|
|
xas_next_offset(xas);
|
|
|
|
while (xas->xa_node && (xas->xa_index <= max)) {
|
|
if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
|
|
xas->xa_offset = xas->xa_node->offset + 1;
|
|
xas->xa_node = xa_parent(xas->xa, xas->xa_node);
|
|
continue;
|
|
}
|
|
|
|
entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
|
|
if (xa_is_node(entry)) {
|
|
xas->xa_node = xa_to_node(entry);
|
|
xas->xa_offset = 0;
|
|
continue;
|
|
}
|
|
if (entry && !xa_is_sibling(entry))
|
|
return entry;
|
|
|
|
xas_next_offset(xas);
|
|
}
|
|
|
|
if (!xas->xa_node)
|
|
xas->xa_node = XAS_BOUNDS;
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_find);
|
|
|
|
/**
|
|
* xas_find_marked() - Find the next marked entry in the XArray.
|
|
* @xas: XArray operation state.
|
|
* @max: Highest index to return.
|
|
* @mark: Mark number to search for.
|
|
*
|
|
* If the @xas has not yet been walked to an entry, return the marked entry
|
|
* which has an index >= xas.xa_index. If it has been walked, the entry
|
|
* currently being pointed at has been processed, and so we return the
|
|
* first marked entry with an index > xas.xa_index.
|
|
*
|
|
* If no marked entry is found and the array is smaller than @max, @xas is
|
|
* set to the bounds state and xas->xa_index is set to the smallest index
|
|
* not yet in the array. This allows @xas to be immediately passed to
|
|
* xas_store().
|
|
*
|
|
* If no entry is found before @max is reached, @xas is set to the restart
|
|
* state.
|
|
*
|
|
* Return: The entry, if found, otherwise %NULL.
|
|
*/
|
|
void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
|
|
{
|
|
bool advance = true;
|
|
unsigned int offset;
|
|
void *entry;
|
|
|
|
if (xas_error(xas))
|
|
return NULL;
|
|
if (xas->xa_index > max)
|
|
goto max;
|
|
|
|
if (!xas->xa_node) {
|
|
xas->xa_index = 1;
|
|
goto out;
|
|
} else if (xas_top(xas->xa_node)) {
|
|
advance = false;
|
|
entry = xa_head(xas->xa);
|
|
xas->xa_node = NULL;
|
|
if (xas->xa_index > max_index(entry))
|
|
goto out;
|
|
if (!xa_is_node(entry)) {
|
|
if (xa_marked(xas->xa, mark))
|
|
return entry;
|
|
xas->xa_index = 1;
|
|
goto out;
|
|
}
|
|
xas->xa_node = xa_to_node(entry);
|
|
xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
|
|
}
|
|
|
|
while (xas->xa_index <= max) {
|
|
if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
|
|
xas->xa_offset = xas->xa_node->offset + 1;
|
|
xas->xa_node = xa_parent(xas->xa, xas->xa_node);
|
|
if (!xas->xa_node)
|
|
break;
|
|
advance = false;
|
|
continue;
|
|
}
|
|
|
|
if (!advance) {
|
|
entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
|
|
if (xa_is_sibling(entry)) {
|
|
xas->xa_offset = xa_to_sibling(entry);
|
|
xas_move_index(xas, xas->xa_offset);
|
|
}
|
|
}
|
|
|
|
offset = xas_find_chunk(xas, advance, mark);
|
|
if (offset > xas->xa_offset) {
|
|
advance = false;
|
|
xas_move_index(xas, offset);
|
|
/* Mind the wrap */
|
|
if ((xas->xa_index - 1) >= max)
|
|
goto max;
|
|
xas->xa_offset = offset;
|
|
if (offset == XA_CHUNK_SIZE)
|
|
continue;
|
|
}
|
|
|
|
entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
|
|
if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
|
|
continue;
|
|
if (!xa_is_node(entry))
|
|
return entry;
|
|
xas->xa_node = xa_to_node(entry);
|
|
xas_set_offset(xas);
|
|
}
|
|
|
|
out:
|
|
if (xas->xa_index > max)
|
|
goto max;
|
|
return set_bounds(xas);
|
|
max:
|
|
xas->xa_node = XAS_RESTART;
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_find_marked);
|
|
|
|
/**
|
|
* xas_find_conflict() - Find the next present entry in a range.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* The @xas describes both a range and a position within that range.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held.
|
|
* Return: The next entry in the range covered by @xas or %NULL.
|
|
*/
|
|
void *xas_find_conflict(struct xa_state *xas)
|
|
{
|
|
void *curr;
|
|
|
|
if (xas_error(xas))
|
|
return NULL;
|
|
|
|
if (!xas->xa_node)
|
|
return NULL;
|
|
|
|
if (xas_top(xas->xa_node)) {
|
|
curr = xas_start(xas);
|
|
if (!curr)
|
|
return NULL;
|
|
while (xa_is_node(curr)) {
|
|
struct xa_node *node = xa_to_node(curr);
|
|
curr = xas_descend(xas, node);
|
|
}
|
|
if (curr)
|
|
return curr;
|
|
}
|
|
|
|
if (xas->xa_node->shift > xas->xa_shift)
|
|
return NULL;
|
|
|
|
for (;;) {
|
|
if (xas->xa_node->shift == xas->xa_shift) {
|
|
if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
|
|
break;
|
|
} else if (xas->xa_offset == XA_CHUNK_MASK) {
|
|
xas->xa_offset = xas->xa_node->offset;
|
|
xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
|
|
if (!xas->xa_node)
|
|
break;
|
|
continue;
|
|
}
|
|
curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
|
|
if (xa_is_sibling(curr))
|
|
continue;
|
|
while (xa_is_node(curr)) {
|
|
xas->xa_node = xa_to_node(curr);
|
|
xas->xa_offset = 0;
|
|
curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
|
|
}
|
|
if (curr)
|
|
return curr;
|
|
}
|
|
xas->xa_offset -= xas->xa_sibs;
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xas_find_conflict);
|
|
|
|
/**
|
|
* xa_load() - Load an entry from an XArray.
|
|
* @xa: XArray.
|
|
* @index: index into array.
|
|
*
|
|
* Context: Any context. Takes and releases the RCU lock.
|
|
* Return: The entry at @index in @xa.
|
|
*/
|
|
void *xa_load(struct xarray *xa, unsigned long index)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *entry;
|
|
|
|
rcu_read_lock();
|
|
do {
|
|
entry = xas_load(&xas);
|
|
if (xa_is_zero(entry))
|
|
entry = NULL;
|
|
} while (xas_retry(&xas, entry));
|
|
rcu_read_unlock();
|
|
|
|
return entry;
|
|
}
|
|
EXPORT_SYMBOL(xa_load);
|
|
|
|
static void *xas_result(struct xa_state *xas, void *curr)
|
|
{
|
|
if (xa_is_zero(curr))
|
|
return NULL;
|
|
if (xas_error(xas))
|
|
curr = xas->xa_node;
|
|
return curr;
|
|
}
|
|
|
|
/**
|
|
* __xa_erase() - Erase this entry from the XArray while locked.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
*
|
|
* After this function returns, loading from @index will return %NULL.
|
|
* If the index is part of a multi-index entry, all indices will be erased
|
|
* and none of the entries will be part of a multi-index entry.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry.
|
|
* Return: The entry which used to be at this index.
|
|
*/
|
|
void *__xa_erase(struct xarray *xa, unsigned long index)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
return xas_result(&xas, xas_store(&xas, NULL));
|
|
}
|
|
EXPORT_SYMBOL(__xa_erase);
|
|
|
|
/**
|
|
* xa_erase() - Erase this entry from the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
*
|
|
* After this function returns, loading from @index will return %NULL.
|
|
* If the index is part of a multi-index entry, all indices will be erased
|
|
* and none of the entries will be part of a multi-index entry.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock.
|
|
* Return: The entry which used to be at this index.
|
|
*/
|
|
void *xa_erase(struct xarray *xa, unsigned long index)
|
|
{
|
|
void *entry;
|
|
|
|
xa_lock(xa);
|
|
entry = __xa_erase(xa, index);
|
|
xa_unlock(xa);
|
|
|
|
return entry;
|
|
}
|
|
EXPORT_SYMBOL(xa_erase);
|
|
|
|
/**
|
|
* __xa_store() - Store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* You must already be holding the xa_lock when calling this function.
|
|
* It will drop the lock if needed to allocate memory, and then reacquire
|
|
* it afterwards.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry. May
|
|
* release and reacquire xa_lock if @gfp flags permit.
|
|
* Return: The old entry at this index or xa_err() if an error happened.
|
|
*/
|
|
void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *curr;
|
|
|
|
if (WARN_ON_ONCE(xa_is_advanced(entry)))
|
|
return XA_ERROR(-EINVAL);
|
|
if (xa_track_free(xa) && !entry)
|
|
entry = XA_ZERO_ENTRY;
|
|
|
|
do {
|
|
curr = xas_store(&xas, entry);
|
|
if (xa_track_free(xa))
|
|
xas_clear_mark(&xas, XA_FREE_MARK);
|
|
} while (__xas_nomem(&xas, gfp));
|
|
|
|
return xas_result(&xas, curr);
|
|
}
|
|
EXPORT_SYMBOL(__xa_store);
|
|
|
|
/**
|
|
* xa_store() - Store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* After this function returns, loads from this index will return @entry.
|
|
* Storing into an existing multi-index entry updates the entry of every index.
|
|
* The marks associated with @index are unaffected unless @entry is %NULL.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock.
|
|
* May sleep if the @gfp flags permit.
|
|
* Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
|
|
* cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
|
|
* failed.
|
|
*/
|
|
void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
|
|
{
|
|
void *curr;
|
|
|
|
xa_lock(xa);
|
|
curr = __xa_store(xa, index, entry, gfp);
|
|
xa_unlock(xa);
|
|
|
|
return curr;
|
|
}
|
|
EXPORT_SYMBOL(xa_store);
|
|
|
|
/**
|
|
* __xa_cmpxchg() - Store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @old: Old value to test against.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* You must already be holding the xa_lock when calling this function.
|
|
* It will drop the lock if needed to allocate memory, and then reacquire
|
|
* it afterwards.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry. May
|
|
* release and reacquire xa_lock if @gfp flags permit.
|
|
* Return: The old entry at this index or xa_err() if an error happened.
|
|
*/
|
|
void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
|
|
void *old, void *entry, gfp_t gfp)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *curr;
|
|
|
|
if (WARN_ON_ONCE(xa_is_advanced(entry)))
|
|
return XA_ERROR(-EINVAL);
|
|
|
|
do {
|
|
curr = xas_load(&xas);
|
|
if (curr == old) {
|
|
xas_store(&xas, entry);
|
|
if (xa_track_free(xa) && entry && !curr)
|
|
xas_clear_mark(&xas, XA_FREE_MARK);
|
|
}
|
|
} while (__xas_nomem(&xas, gfp));
|
|
|
|
return xas_result(&xas, curr);
|
|
}
|
|
EXPORT_SYMBOL(__xa_cmpxchg);
|
|
|
|
/**
|
|
* __xa_insert() - Store this entry in the XArray if no entry is present.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve())
|
|
* if no entry is present. Inserting will fail if a reserved entry is
|
|
* present, even though loading from this index will return NULL.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry. May
|
|
* release and reacquire xa_lock if @gfp flags permit.
|
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present.
|
|
* -ENOMEM if memory could not be allocated.
|
|
*/
|
|
int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *curr;
|
|
|
|
if (WARN_ON_ONCE(xa_is_advanced(entry)))
|
|
return -EINVAL;
|
|
if (!entry)
|
|
entry = XA_ZERO_ENTRY;
|
|
|
|
do {
|
|
curr = xas_load(&xas);
|
|
if (!curr) {
|
|
xas_store(&xas, entry);
|
|
if (xa_track_free(xa))
|
|
xas_clear_mark(&xas, XA_FREE_MARK);
|
|
} else {
|
|
xas_set_err(&xas, -EBUSY);
|
|
}
|
|
} while (__xas_nomem(&xas, gfp));
|
|
|
|
return xas_error(&xas);
|
|
}
|
|
EXPORT_SYMBOL(__xa_insert);
|
|
|
|
#ifdef CONFIG_XARRAY_MULTI
|
|
static void xas_set_range(struct xa_state *xas, unsigned long first,
|
|
unsigned long last)
|
|
{
|
|
unsigned int shift = 0;
|
|
unsigned long sibs = last - first;
|
|
unsigned int offset = XA_CHUNK_MASK;
|
|
|
|
xas_set(xas, first);
|
|
|
|
while ((first & XA_CHUNK_MASK) == 0) {
|
|
if (sibs < XA_CHUNK_MASK)
|
|
break;
|
|
if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
|
|
break;
|
|
shift += XA_CHUNK_SHIFT;
|
|
if (offset == XA_CHUNK_MASK)
|
|
offset = sibs & XA_CHUNK_MASK;
|
|
sibs >>= XA_CHUNK_SHIFT;
|
|
first >>= XA_CHUNK_SHIFT;
|
|
}
|
|
|
|
offset = first & XA_CHUNK_MASK;
|
|
if (offset + sibs > XA_CHUNK_MASK)
|
|
sibs = XA_CHUNK_MASK - offset;
|
|
if ((((first + sibs + 1) << shift) - 1) > last)
|
|
sibs -= 1;
|
|
|
|
xas->xa_shift = shift;
|
|
xas->xa_sibs = sibs;
|
|
}
|
|
|
|
/**
|
|
* xa_store_range() - Store this entry at a range of indices in the XArray.
|
|
* @xa: XArray.
|
|
* @first: First index to affect.
|
|
* @last: Last index to affect.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* After this function returns, loads from any index between @first and @last,
|
|
* inclusive will return @entry.
|
|
* Storing into an existing multi-index entry updates the entry of every index.
|
|
* The marks associated with @index are unaffected unless @entry is %NULL.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock. May sleep
|
|
* if the @gfp flags permit.
|
|
* Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
|
|
* an XArray, or xa_err(-ENOMEM) if memory allocation failed.
|
|
*/
|
|
void *xa_store_range(struct xarray *xa, unsigned long first,
|
|
unsigned long last, void *entry, gfp_t gfp)
|
|
{
|
|
XA_STATE(xas, xa, 0);
|
|
|
|
if (WARN_ON_ONCE(xa_is_internal(entry)))
|
|
return XA_ERROR(-EINVAL);
|
|
if (last < first)
|
|
return XA_ERROR(-EINVAL);
|
|
|
|
do {
|
|
xas_lock(&xas);
|
|
if (entry) {
|
|
unsigned int order = BITS_PER_LONG;
|
|
if (last + 1)
|
|
order = __ffs(last + 1);
|
|
xas_set_order(&xas, last, order);
|
|
xas_create(&xas, true);
|
|
if (xas_error(&xas))
|
|
goto unlock;
|
|
}
|
|
do {
|
|
xas_set_range(&xas, first, last);
|
|
xas_store(&xas, entry);
|
|
if (xas_error(&xas))
|
|
goto unlock;
|
|
first += xas_size(&xas);
|
|
} while (first <= last);
|
|
unlock:
|
|
xas_unlock(&xas);
|
|
} while (xas_nomem(&xas, gfp));
|
|
|
|
return xas_result(&xas, NULL);
|
|
}
|
|
EXPORT_SYMBOL(xa_store_range);
|
|
|
|
/**
|
|
* xa_get_order() - Get the order of an entry.
|
|
* @xa: XArray.
|
|
* @index: Index of the entry.
|
|
*
|
|
* Return: A number between 0 and 63 indicating the order of the entry.
|
|
*/
|
|
int xa_get_order(struct xarray *xa, unsigned long index)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *entry;
|
|
int order = 0;
|
|
|
|
rcu_read_lock();
|
|
entry = xas_load(&xas);
|
|
|
|
if (!entry)
|
|
goto unlock;
|
|
|
|
if (!xas.xa_node)
|
|
goto unlock;
|
|
|
|
for (;;) {
|
|
unsigned int slot = xas.xa_offset + (1 << order);
|
|
|
|
if (slot >= XA_CHUNK_SIZE)
|
|
break;
|
|
if (!xa_is_sibling(xas.xa_node->slots[slot]))
|
|
break;
|
|
order++;
|
|
}
|
|
|
|
order += xas.xa_node->shift;
|
|
unlock:
|
|
rcu_read_unlock();
|
|
|
|
return order;
|
|
}
|
|
EXPORT_SYMBOL(xa_get_order);
|
|
#endif /* CONFIG_XARRAY_MULTI */
|
|
|
|
/**
|
|
* __xa_alloc() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @limit: Range for allocated ID.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry. May
|
|
* release and reacquire xa_lock if @gfp flags permit.
|
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or
|
|
* -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
|
|
struct xa_limit limit, gfp_t gfp)
|
|
{
|
|
XA_STATE(xas, xa, 0);
|
|
|
|
if (WARN_ON_ONCE(xa_is_advanced(entry)))
|
|
return -EINVAL;
|
|
if (WARN_ON_ONCE(!xa_track_free(xa)))
|
|
return -EINVAL;
|
|
|
|
if (!entry)
|
|
entry = XA_ZERO_ENTRY;
|
|
|
|
do {
|
|
xas.xa_index = limit.min;
|
|
xas_find_marked(&xas, limit.max, XA_FREE_MARK);
|
|
if (xas.xa_node == XAS_RESTART)
|
|
xas_set_err(&xas, -EBUSY);
|
|
else
|
|
*id = xas.xa_index;
|
|
xas_store(&xas, entry);
|
|
xas_clear_mark(&xas, XA_FREE_MARK);
|
|
} while (__xas_nomem(&xas, gfp));
|
|
|
|
return xas_error(&xas);
|
|
}
|
|
EXPORT_SYMBOL(__xa_alloc);
|
|
|
|
/**
|
|
* __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of allocated ID.
|
|
* @next: Pointer to next ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
* The search for an empty entry will start at @next and will wrap
|
|
* around if necessary.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry. May
|
|
* release and reacquire xa_lock if @gfp flags permit.
|
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the
|
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be
|
|
* allocated or -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
|
|
struct xa_limit limit, u32 *next, gfp_t gfp)
|
|
{
|
|
u32 min = limit.min;
|
|
int ret;
|
|
|
|
limit.min = max(min, *next);
|
|
ret = __xa_alloc(xa, id, entry, limit, gfp);
|
|
if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
|
|
xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
|
|
ret = 1;
|
|
}
|
|
|
|
if (ret < 0 && limit.min > min) {
|
|
limit.min = min;
|
|
ret = __xa_alloc(xa, id, entry, limit, gfp);
|
|
if (ret == 0)
|
|
ret = 1;
|
|
}
|
|
|
|
if (ret >= 0) {
|
|
*next = *id + 1;
|
|
if (*next == 0)
|
|
xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__xa_alloc_cyclic);
|
|
|
|
/**
|
|
* __xa_set_mark() - Set this mark on this entry while locked.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
* @mark: Mark number.
|
|
*
|
|
* Attempting to set a mark on a %NULL entry does not succeed.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry.
|
|
*/
|
|
void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *entry = xas_load(&xas);
|
|
|
|
if (entry)
|
|
xas_set_mark(&xas, mark);
|
|
}
|
|
EXPORT_SYMBOL(__xa_set_mark);
|
|
|
|
/**
|
|
* __xa_clear_mark() - Clear this mark on this entry while locked.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
* @mark: Mark number.
|
|
*
|
|
* Context: Any context. Expects xa_lock to be held on entry.
|
|
*/
|
|
void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *entry = xas_load(&xas);
|
|
|
|
if (entry)
|
|
xas_clear_mark(&xas, mark);
|
|
}
|
|
EXPORT_SYMBOL(__xa_clear_mark);
|
|
|
|
/**
|
|
* xa_get_mark() - Inquire whether this mark is set on this entry.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
* @mark: Mark number.
|
|
*
|
|
* This function uses the RCU read lock, so the result may be out of date
|
|
* by the time it returns. If you need the result to be stable, use a lock.
|
|
*
|
|
* Context: Any context. Takes and releases the RCU lock.
|
|
* Return: True if the entry at @index has this mark set, false if it doesn't.
|
|
*/
|
|
bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
void *entry;
|
|
|
|
rcu_read_lock();
|
|
entry = xas_start(&xas);
|
|
while (xas_get_mark(&xas, mark)) {
|
|
if (!xa_is_node(entry))
|
|
goto found;
|
|
entry = xas_descend(&xas, xa_to_node(entry));
|
|
}
|
|
rcu_read_unlock();
|
|
return false;
|
|
found:
|
|
rcu_read_unlock();
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(xa_get_mark);
|
|
|
|
/**
|
|
* xa_set_mark() - Set this mark on this entry.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
* @mark: Mark number.
|
|
*
|
|
* Attempting to set a mark on a %NULL entry does not succeed.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock.
|
|
*/
|
|
void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
|
|
{
|
|
xa_lock(xa);
|
|
__xa_set_mark(xa, index, mark);
|
|
xa_unlock(xa);
|
|
}
|
|
EXPORT_SYMBOL(xa_set_mark);
|
|
|
|
/**
|
|
* xa_clear_mark() - Clear this mark on this entry.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
* @mark: Mark number.
|
|
*
|
|
* Clearing a mark always succeeds.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock.
|
|
*/
|
|
void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
|
|
{
|
|
xa_lock(xa);
|
|
__xa_clear_mark(xa, index, mark);
|
|
xa_unlock(xa);
|
|
}
|
|
EXPORT_SYMBOL(xa_clear_mark);
|
|
|
|
/**
|
|
* xa_find() - Search the XArray for an entry.
|
|
* @xa: XArray.
|
|
* @indexp: Pointer to an index.
|
|
* @max: Maximum index to search to.
|
|
* @filter: Selection criterion.
|
|
*
|
|
* Finds the entry in @xa which matches the @filter, and has the lowest
|
|
* index that is at least @indexp and no more than @max.
|
|
* If an entry is found, @indexp is updated to be the index of the entry.
|
|
* This function is protected by the RCU read lock, so it may not find
|
|
* entries which are being simultaneously added. It will not return an
|
|
* %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
|
|
*
|
|
* Context: Any context. Takes and releases the RCU lock.
|
|
* Return: The entry, if found, otherwise %NULL.
|
|
*/
|
|
void *xa_find(struct xarray *xa, unsigned long *indexp,
|
|
unsigned long max, xa_mark_t filter)
|
|
{
|
|
XA_STATE(xas, xa, *indexp);
|
|
void *entry;
|
|
|
|
rcu_read_lock();
|
|
do {
|
|
if ((__force unsigned int)filter < XA_MAX_MARKS)
|
|
entry = xas_find_marked(&xas, max, filter);
|
|
else
|
|
entry = xas_find(&xas, max);
|
|
} while (xas_retry(&xas, entry));
|
|
rcu_read_unlock();
|
|
|
|
if (entry)
|
|
*indexp = xas.xa_index;
|
|
return entry;
|
|
}
|
|
EXPORT_SYMBOL(xa_find);
|
|
|
|
static bool xas_sibling(struct xa_state *xas)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
unsigned long mask;
|
|
|
|
if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
|
|
return false;
|
|
mask = (XA_CHUNK_SIZE << node->shift) - 1;
|
|
return (xas->xa_index & mask) >
|
|
((unsigned long)xas->xa_offset << node->shift);
|
|
}
|
|
|
|
/**
|
|
* xa_find_after() - Search the XArray for a present entry.
|
|
* @xa: XArray.
|
|
* @indexp: Pointer to an index.
|
|
* @max: Maximum index to search to.
|
|
* @filter: Selection criterion.
|
|
*
|
|
* Finds the entry in @xa which matches the @filter and has the lowest
|
|
* index that is above @indexp and no more than @max.
|
|
* If an entry is found, @indexp is updated to be the index of the entry.
|
|
* This function is protected by the RCU read lock, so it may miss entries
|
|
* which are being simultaneously added. It will not return an
|
|
* %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
|
|
*
|
|
* Context: Any context. Takes and releases the RCU lock.
|
|
* Return: The pointer, if found, otherwise %NULL.
|
|
*/
|
|
void *xa_find_after(struct xarray *xa, unsigned long *indexp,
|
|
unsigned long max, xa_mark_t filter)
|
|
{
|
|
XA_STATE(xas, xa, *indexp + 1);
|
|
void *entry;
|
|
|
|
if (xas.xa_index == 0)
|
|
return NULL;
|
|
|
|
rcu_read_lock();
|
|
for (;;) {
|
|
if ((__force unsigned int)filter < XA_MAX_MARKS)
|
|
entry = xas_find_marked(&xas, max, filter);
|
|
else
|
|
entry = xas_find(&xas, max);
|
|
|
|
if (xas_invalid(&xas))
|
|
break;
|
|
if (xas_sibling(&xas))
|
|
continue;
|
|
if (!xas_retry(&xas, entry))
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if (entry)
|
|
*indexp = xas.xa_index;
|
|
return entry;
|
|
}
|
|
EXPORT_SYMBOL(xa_find_after);
|
|
|
|
static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
|
|
unsigned long max, unsigned int n)
|
|
{
|
|
void *entry;
|
|
unsigned int i = 0;
|
|
|
|
rcu_read_lock();
|
|
xas_for_each(xas, entry, max) {
|
|
if (xas_retry(xas, entry))
|
|
continue;
|
|
dst[i++] = entry;
|
|
if (i == n)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return i;
|
|
}
|
|
|
|
static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
|
|
unsigned long max, unsigned int n, xa_mark_t mark)
|
|
{
|
|
void *entry;
|
|
unsigned int i = 0;
|
|
|
|
rcu_read_lock();
|
|
xas_for_each_marked(xas, entry, max, mark) {
|
|
if (xas_retry(xas, entry))
|
|
continue;
|
|
dst[i++] = entry;
|
|
if (i == n)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return i;
|
|
}
|
|
|
|
/**
|
|
* xa_extract() - Copy selected entries from the XArray into a normal array.
|
|
* @xa: The source XArray to copy from.
|
|
* @dst: The buffer to copy entries into.
|
|
* @start: The first index in the XArray eligible to be selected.
|
|
* @max: The last index in the XArray eligible to be selected.
|
|
* @n: The maximum number of entries to copy.
|
|
* @filter: Selection criterion.
|
|
*
|
|
* Copies up to @n entries that match @filter from the XArray. The
|
|
* copied entries will have indices between @start and @max, inclusive.
|
|
*
|
|
* The @filter may be an XArray mark value, in which case entries which are
|
|
* marked with that mark will be copied. It may also be %XA_PRESENT, in
|
|
* which case all entries which are not %NULL will be copied.
|
|
*
|
|
* The entries returned may not represent a snapshot of the XArray at a
|
|
* moment in time. For example, if another thread stores to index 5, then
|
|
* index 10, calling xa_extract() may return the old contents of index 5
|
|
* and the new contents of index 10. Indices not modified while this
|
|
* function is running will not be skipped.
|
|
*
|
|
* If you need stronger guarantees, holding the xa_lock across calls to this
|
|
* function will prevent concurrent modification.
|
|
*
|
|
* Context: Any context. Takes and releases the RCU lock.
|
|
* Return: The number of entries copied.
|
|
*/
|
|
unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
|
|
unsigned long max, unsigned int n, xa_mark_t filter)
|
|
{
|
|
XA_STATE(xas, xa, start);
|
|
|
|
if (!n)
|
|
return 0;
|
|
|
|
if ((__force unsigned int)filter < XA_MAX_MARKS)
|
|
return xas_extract_marked(&xas, dst, max, n, filter);
|
|
return xas_extract_present(&xas, dst, max, n);
|
|
}
|
|
EXPORT_SYMBOL(xa_extract);
|
|
|
|
/**
|
|
* xa_delete_node() - Private interface for workingset code.
|
|
* @node: Node to be removed from the tree.
|
|
* @update: Function to call to update ancestor nodes.
|
|
*
|
|
* Context: xa_lock must be held on entry and will not be released.
|
|
*/
|
|
void xa_delete_node(struct xa_node *node, xa_update_node_t update)
|
|
{
|
|
struct xa_state xas = {
|
|
.xa = node->array,
|
|
.xa_index = (unsigned long)node->offset <<
|
|
(node->shift + XA_CHUNK_SHIFT),
|
|
.xa_shift = node->shift + XA_CHUNK_SHIFT,
|
|
.xa_offset = node->offset,
|
|
.xa_node = xa_parent_locked(node->array, node),
|
|
.xa_update = update,
|
|
};
|
|
|
|
xas_store(&xas, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
|
|
|
|
/**
|
|
* xa_destroy() - Free all internal data structures.
|
|
* @xa: XArray.
|
|
*
|
|
* After calling this function, the XArray is empty and has freed all memory
|
|
* allocated for its internal data structures. You are responsible for
|
|
* freeing the objects referenced by the XArray.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock, interrupt-safe.
|
|
*/
|
|
void xa_destroy(struct xarray *xa)
|
|
{
|
|
XA_STATE(xas, xa, 0);
|
|
unsigned long flags;
|
|
void *entry;
|
|
|
|
xas.xa_node = NULL;
|
|
xas_lock_irqsave(&xas, flags);
|
|
entry = xa_head_locked(xa);
|
|
RCU_INIT_POINTER(xa->xa_head, NULL);
|
|
xas_init_marks(&xas);
|
|
if (xa_zero_busy(xa))
|
|
xa_mark_clear(xa, XA_FREE_MARK);
|
|
/* lockdep checks we're still holding the lock in xas_free_nodes() */
|
|
if (xa_is_node(entry))
|
|
xas_free_nodes(&xas, xa_to_node(entry));
|
|
xas_unlock_irqrestore(&xas, flags);
|
|
}
|
|
EXPORT_SYMBOL(xa_destroy);
|
|
|
|
#ifdef XA_DEBUG
|
|
void xa_dump_node(const struct xa_node *node)
|
|
{
|
|
unsigned i, j;
|
|
|
|
if (!node)
|
|
return;
|
|
if ((unsigned long)node & 3) {
|
|
pr_cont("node %px\n", node);
|
|
return;
|
|
}
|
|
|
|
pr_cont("node %px %s %d parent %px shift %d count %d values %d "
|
|
"array %px list %px %px marks",
|
|
node, node->parent ? "offset" : "max", node->offset,
|
|
node->parent, node->shift, node->count, node->nr_values,
|
|
node->array, node->private_list.prev, node->private_list.next);
|
|
for (i = 0; i < XA_MAX_MARKS; i++)
|
|
for (j = 0; j < XA_MARK_LONGS; j++)
|
|
pr_cont(" %lx", node->marks[i][j]);
|
|
pr_cont("\n");
|
|
}
|
|
|
|
void xa_dump_index(unsigned long index, unsigned int shift)
|
|
{
|
|
if (!shift)
|
|
pr_info("%lu: ", index);
|
|
else if (shift >= BITS_PER_LONG)
|
|
pr_info("0-%lu: ", ~0UL);
|
|
else
|
|
pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
|
|
}
|
|
|
|
void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
|
|
{
|
|
if (!entry)
|
|
return;
|
|
|
|
xa_dump_index(index, shift);
|
|
|
|
if (xa_is_node(entry)) {
|
|
if (shift == 0) {
|
|
pr_cont("%px\n", entry);
|
|
} else {
|
|
unsigned long i;
|
|
struct xa_node *node = xa_to_node(entry);
|
|
xa_dump_node(node);
|
|
for (i = 0; i < XA_CHUNK_SIZE; i++)
|
|
xa_dump_entry(node->slots[i],
|
|
index + (i << node->shift), node->shift);
|
|
}
|
|
} else if (xa_is_value(entry))
|
|
pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
|
|
xa_to_value(entry), entry);
|
|
else if (!xa_is_internal(entry))
|
|
pr_cont("%px\n", entry);
|
|
else if (xa_is_retry(entry))
|
|
pr_cont("retry (%ld)\n", xa_to_internal(entry));
|
|
else if (xa_is_sibling(entry))
|
|
pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
|
|
else if (xa_is_zero(entry))
|
|
pr_cont("zero (%ld)\n", xa_to_internal(entry));
|
|
else
|
|
pr_cont("UNKNOWN ENTRY (%px)\n", entry);
|
|
}
|
|
|
|
void xa_dump(const struct xarray *xa)
|
|
{
|
|
void *entry = xa->xa_head;
|
|
unsigned int shift = 0;
|
|
|
|
pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
|
|
xa->xa_flags, xa_marked(xa, XA_MARK_0),
|
|
xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
|
|
if (xa_is_node(entry))
|
|
shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
|
|
xa_dump_entry(entry, 0, shift);
|
|
}
|
|
#endif
|