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xarray: Add XArray iterators 

The xa_for_each iterator allows the user to efficiently walk a range
of the array, executing the loop body once for each entry in that
range that matches the filter.  This commit also includes xa_find()
and xa_find_after() which are helper functions for xa_for_each() but
may also be useful in their own right.

In the xas family of functions, we have xas_for_each(), xas_find(),
xas_next_entry(), xas_for_each_tagged(), xas_find_tagged(),
xas_next_tagged() and xas_pause().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2017-11-14 08:30:11 -05:00
parent 41aec91f55
commit b803b42823
3 changed files with 640 additions and 0 deletions
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165
include/linux/xarray.h
View File

@ -280,6 +280,10 @@ void *xa_cmpxchg(struct xarray *, unsigned long index,
bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t); bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t); void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t); void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
void *xa_find(struct xarray *xa, unsigned long *index,
unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
void *xa_find_after(struct xarray *xa, unsigned long *index,
unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
/** /**
* xa_init() - Initialise an empty XArray. * xa_init() - Initialise an empty XArray.
@ -364,6 +368,35 @@ static inline int xa_insert(struct xarray *xa, unsigned long index,
return -EEXIST; return -EEXIST;
} }
/**
* xa_for_each() - Iterate over a portion of an XArray.
* @xa: XArray.
* @entry: Entry retrieved from array.
* @index: Index of @entry.
* @max: Maximum index to retrieve from array.
* @filter: Selection criterion.
*
* Initialise @index to the lowest index you want to retrieve from the
* array. During the iteration, @entry will have the value of the entry
* stored in @xa at @index. The iteration will skip all entries in the
* array which do not match @filter. You may modify @index during the
* iteration if you want to skip or reprocess indices. It is safe to modify
* the array during the iteration. At the end of the iteration, @entry will
* be set to NULL and @index will have a value less than or equal to max.
*
* xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have
* to handle your own locking with xas_for_each(), and if you have to unlock
* after each iteration, it will also end up being O(n.log(n)). xa_for_each()
* will spin if it hits a retry entry; if you intend to see retry entries,
* you should use the xas_for_each() iterator instead. The xas_for_each()
* iterator will expand into more inline code than xa_for_each().
*
* Context: Any context. Takes and releases the RCU lock.
*/
#define xa_for_each(xa, entry, index, max, filter) \
for (entry = xa_find(xa, &index, max, filter); entry; \
entry = xa_find_after(xa, &index, max, filter))
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock) #define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
#define xa_lock(xa) spin_lock(&(xa)->xa_lock) #define xa_lock(xa) spin_lock(&(xa)->xa_lock)
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock) #define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
@ -835,13 +868,16 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
void *xas_load(struct xa_state *); void *xas_load(struct xa_state *);
void *xas_store(struct xa_state *, void *entry); void *xas_store(struct xa_state *, void *entry);
void *xas_find(struct xa_state *, unsigned long max);
bool xas_get_mark(const struct xa_state *, xa_mark_t); bool xas_get_mark(const struct xa_state *, xa_mark_t);
void xas_set_mark(const struct xa_state *, xa_mark_t); void xas_set_mark(const struct xa_state *, xa_mark_t);
void xas_clear_mark(const struct xa_state *, xa_mark_t); void xas_clear_mark(const struct xa_state *, xa_mark_t);
void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
void xas_init_marks(const struct xa_state *); void xas_init_marks(const struct xa_state *);
bool xas_nomem(struct xa_state *, gfp_t); bool xas_nomem(struct xa_state *, gfp_t);
void xas_pause(struct xa_state *);
/** /**
* xas_reload() - Refetch an entry from the xarray. * xas_reload() - Refetch an entry from the xarray.
@ -914,4 +950,133 @@ static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
xas->xa_update = update; xas->xa_update = update;
} }
/**
* xas_next_entry() - Advance iterator to next present entry.
* @xas: XArray operation state.
* @max: Highest index to return.
*
* xas_next_entry() is an inline function to optimise xarray traversal for
* speed. It is equivalent to calling xas_find(), and will call xas_find()
* for all the hard cases.
*
* Return: The next present entry after the one currently referred to by @xas.
*/
static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
{
struct xa_node *node = xas->xa_node;
void *entry;
if (unlikely(xas_not_node(node) || node->shift ||
xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
return xas_find(xas, max);
do {
if (unlikely(xas->xa_index >= max))
return xas_find(xas, max);
if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
return xas_find(xas, max);
entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
if (unlikely(xa_is_internal(entry)))
return xas_find(xas, max);
xas->xa_offset++;
xas->xa_index++;
} while (!entry);
return entry;
}
/* Private */
static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
xa_mark_t mark)
{
unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
unsigned int offset = xas->xa_offset;
if (advance)
offset++;
if (XA_CHUNK_SIZE == BITS_PER_LONG) {
if (offset < XA_CHUNK_SIZE) {
unsigned long data = *addr & (~0UL << offset);
if (data)
return __ffs(data);
}
return XA_CHUNK_SIZE;
}
return find_next_bit(addr, XA_CHUNK_SIZE, offset);
}
/**
* xas_next_marked() - Advance iterator to next marked entry.
* @xas: XArray operation state.
* @max: Highest index to return.
* @mark: Mark to search for.
*
* xas_next_marked() is an inline function to optimise xarray traversal for
* speed. It is equivalent to calling xas_find_marked(), and will call
* xas_find_marked() for all the hard cases.
*
* Return: The next marked entry after the one currently referred to by @xas.
*/
static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
xa_mark_t mark)
{
struct xa_node *node = xas->xa_node;
unsigned int offset;
if (unlikely(xas_not_node(node) || node->shift))
return xas_find_marked(xas, max, mark);
offset = xas_find_chunk(xas, true, mark);
xas->xa_offset = offset;
xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
if (xas->xa_index > max)
return NULL;
if (offset == XA_CHUNK_SIZE)
return xas_find_marked(xas, max, mark);
return xa_entry(xas->xa, node, offset);
}
/*
* If iterating while holding a lock, drop the lock and reschedule
* every %XA_CHECK_SCHED loops.
*/
enum {
XA_CHECK_SCHED = 4096,
};
/**
* xas_for_each() - Iterate over a range of an XArray.
* @xas: XArray operation state.
* @entry: Entry retrieved from the array.
* @max: Maximum index to retrieve from array.
*
* The loop body will be executed for each entry present in the xarray
* between the current xas position and @max. @entry will be set to
* the entry retrieved from the xarray. It is safe to delete entries
* from the array in the loop body. You should hold either the RCU lock
* or the xa_lock while iterating. If you need to drop the lock, call
* xas_pause() first.
*/
#define xas_for_each(xas, entry, max) \
for (entry = xas_find(xas, max); entry; \
entry = xas_next_entry(xas, max))
/**
* xas_for_each_marked() - Iterate over a range of an XArray.
* @xas: XArray operation state.
* @entry: Entry retrieved from the array.
* @max: Maximum index to retrieve from array.
* @mark: Mark to search for.
*
* The loop body will be executed for each marked entry in the xarray
* between the current xas position and @max. @entry will be set to
* the entry retrieved from the xarray. It is safe to delete entries
* from the array in the loop body. You should hold either the RCU lock
* or the xa_lock while iterating. If you need to drop the lock, call
* xas_pause() first.
*/
#define xas_for_each_marked(xas, entry, max, mark) \
for (entry = xas_find_marked(xas, max, mark); entry; \
entry = xas_next_marked(xas, max, mark))
#endif /* _LINUX_XARRAY_H */ #endif /* _LINUX_XARRAY_H */

183
lib/test_xarray.c
View File

@ -75,6 +75,48 @@ static noinline void check_xa_err(struct xarray *xa)
// XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL); // XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL);
} }
static noinline void check_xas_retry(struct xarray *xa)
{
XA_STATE(xas, xa, 0);
void *entry;
xa_store_index(xa, 0, GFP_KERNEL);
xa_store_index(xa, 1, GFP_KERNEL);
rcu_read_lock();
XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_value(0));
xa_erase_index(xa, 1);
XA_BUG_ON(xa, !xa_is_retry(xas_reload(&xas)));
XA_BUG_ON(xa, xas_retry(&xas, NULL));
XA_BUG_ON(xa, xas_retry(&xas, xa_mk_value(0)));
xas_reset(&xas);
XA_BUG_ON(xa, xas.xa_node != XAS_RESTART);
XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
XA_BUG_ON(xa, xas.xa_node != NULL);
XA_BUG_ON(xa, xa_store_index(xa, 1, GFP_KERNEL) != NULL);
XA_BUG_ON(xa, !xa_is_internal(xas_reload(&xas)));
xas.xa_node = XAS_RESTART;
XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
rcu_read_unlock();
/* Make sure we can iterate through retry entries */
xas_lock(&xas);
xas_set(&xas, 0);
xas_store(&xas, XA_RETRY_ENTRY);
xas_set(&xas, 1);
xas_store(&xas, XA_RETRY_ENTRY);
xas_set(&xas, 0);
xas_for_each(&xas, entry, ULONG_MAX) {
xas_store(&xas, xa_mk_value(xas.xa_index));
}
xas_unlock(&xas);
xa_erase_index(xa, 0);
xa_erase_index(xa, 1);
}
static noinline void check_xa_load(struct xarray *xa) static noinline void check_xa_load(struct xarray *xa)
{ {
unsigned long i, j; unsigned long i, j;
@ -217,6 +259,44 @@ static noinline void check_cmpxchg(struct xarray *xa)
XA_BUG_ON(xa, !xa_empty(xa)); XA_BUG_ON(xa, !xa_empty(xa));
} }
static noinline void check_xas_erase(struct xarray *xa)
{
XA_STATE(xas, xa, 0);
void *entry;
unsigned long i, j;
for (i = 0; i < 200; i++) {
for (j = i; j < 2 * i + 17; j++) {
xas_set(&xas, j);
do {
xas_lock(&xas);
xas_store(&xas, xa_mk_value(j));
xas_unlock(&xas);
} while (xas_nomem(&xas, GFP_KERNEL));
}
xas_set(&xas, ULONG_MAX);
do {
xas_lock(&xas);
xas_store(&xas, xa_mk_value(0));
xas_unlock(&xas);
} while (xas_nomem(&xas, GFP_KERNEL));
xas_lock(&xas);
xas_store(&xas, NULL);
xas_set(&xas, 0);
j = i;
xas_for_each(&xas, entry, ULONG_MAX) {
XA_BUG_ON(xa, entry != xa_mk_value(j));
xas_store(&xas, NULL);
j++;
}
xas_unlock(&xas);
XA_BUG_ON(xa, !xa_empty(xa));
}
}
static noinline void check_multi_store(struct xarray *xa) static noinline void check_multi_store(struct xarray *xa)
{ {
#ifdef CONFIG_XARRAY_MULTI #ifdef CONFIG_XARRAY_MULTI
@ -285,16 +365,119 @@ static noinline void check_multi_store(struct xarray *xa)
#endif #endif
} }
static noinline void check_multi_find(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
unsigned long index;
xa_store_order(xa, 12, 2, xa_mk_value(12), GFP_KERNEL);
XA_BUG_ON(xa, xa_store_index(xa, 16, GFP_KERNEL) != NULL);
index = 0;
XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
xa_mk_value(12));
XA_BUG_ON(xa, index != 12);
index = 13;
XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
xa_mk_value(12));
XA_BUG_ON(xa, (index < 12) || (index >= 16));
XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=
xa_mk_value(16));
XA_BUG_ON(xa, index != 16);
xa_erase_index(xa, 12);
xa_erase_index(xa, 16);
XA_BUG_ON(xa, !xa_empty(xa));
#endif
}
static noinline void check_multi_find_2(struct xarray *xa)
{
unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 10 : 1;
unsigned int i, j;
void *entry;
for (i = 0; i < max_order; i++) {
unsigned long index = 1UL << i;
for (j = 0; j < index; j++) {
XA_STATE(xas, xa, j + index);
xa_store_index(xa, index - 1, GFP_KERNEL);
xa_store_order(xa, index, i, xa_mk_value(index),
GFP_KERNEL);
rcu_read_lock();
xas_for_each(&xas, entry, ULONG_MAX) {
xa_erase_index(xa, index);
}
rcu_read_unlock();
xa_erase_index(xa, index - 1);
XA_BUG_ON(xa, !xa_empty(xa));
}
}
}
static noinline void check_find(struct xarray *xa)
{
unsigned long i, j, k;
XA_BUG_ON(xa, !xa_empty(xa));
/*
* Check xa_find with all pairs between 0 and 99 inclusive,
* starting at every index between 0 and 99
*/
for (i = 0; i < 100; i++) {
XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
xa_set_mark(xa, i, XA_MARK_0);
for (j = 0; j < i; j++) {
XA_BUG_ON(xa, xa_store_index(xa, j, GFP_KERNEL) !=
NULL);
xa_set_mark(xa, j, XA_MARK_0);
for (k = 0; k < 100; k++) {
unsigned long index = k;
void *entry = xa_find(xa, &index, ULONG_MAX,
XA_PRESENT);
if (k <= j)
XA_BUG_ON(xa, index != j);
else if (k <= i)
XA_BUG_ON(xa, index != i);
else
XA_BUG_ON(xa, entry != NULL);
index = k;
entry = xa_find(xa, &index, ULONG_MAX,
XA_MARK_0);
if (k <= j)
XA_BUG_ON(xa, index != j);
else if (k <= i)
XA_BUG_ON(xa, index != i);
else
XA_BUG_ON(xa, entry != NULL);
}
xa_erase_index(xa, j);
XA_BUG_ON(xa, xa_get_mark(xa, j, XA_MARK_0));
XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0));
}
xa_erase_index(xa, i);
XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_0));
}
XA_BUG_ON(xa, !xa_empty(xa));
check_multi_find(xa);
check_multi_find_2(xa);
}
static DEFINE_XARRAY(array); static DEFINE_XARRAY(array);
static int xarray_checks(void) static int xarray_checks(void)
{ {
check_xa_err(&array); check_xa_err(&array);
check_xas_retry(&array);
check_xa_load(&array); check_xa_load(&array);
check_xa_mark(&array); check_xa_mark(&array);
check_xa_shrink(&array); check_xa_shrink(&array);
check_xas_erase(&array);
check_cmpxchg(&array); check_cmpxchg(&array);
check_multi_store(&array); check_multi_store(&array);
check_find(&array);
printk("XArray: %u of %u tests passed\n", tests_passed, tests_run); printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
return (tests_run == tests_passed) ? 0 : -EINVAL; return (tests_run == tests_passed) ? 0 : -EINVAL;

292
lib/xarray.c
View File

@ -128,6 +128,11 @@ static unsigned int get_offset(unsigned long index, struct xa_node *node)
return (index >> node->shift) & XA_CHUNK_MASK; return (index >> node->shift) & XA_CHUNK_MASK;
} }
static void xas_set_offset(struct xa_state *xas)
{
xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
}
/* move the index either forwards (find) or backwards (sibling slot) */ /* move the index either forwards (find) or backwards (sibling slot) */
static void xas_move_index(struct xa_state *xas, unsigned long offset) static void xas_move_index(struct xa_state *xas, unsigned long offset)
{ {
@ -136,6 +141,12 @@ static void xas_move_index(struct xa_state *xas, unsigned long offset)
xas->xa_index += offset << shift; xas->xa_index += offset << shift;
} }
static void xas_advance(struct xa_state *xas)
{
xas->xa_offset++;
xas_move_index(xas, xas->xa_offset);
}
static void *set_bounds(struct xa_state *xas) static void *set_bounds(struct xa_state *xas)
{ {
xas->xa_node = XAS_BOUNDS; xas->xa_node = XAS_BOUNDS;
@ -829,6 +840,202 @@ void xas_init_marks(const struct xa_state *xas)
} }
EXPORT_SYMBOL_GPL(xas_init_marks); EXPORT_SYMBOL_GPL(xas_init_marks);
/**
* 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;
if (node) {
unsigned int 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;
} else {
xas->xa_index++;
}
xas->xa_node = XAS_RESTART;
}
EXPORT_SYMBOL_GPL(xas_pause);
/**
* 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))
return NULL;
if (!xas->xa_node) {
xas->xa_index = 1;
return set_bounds(xas);
} else if (xas_top(xas->xa_node)) {
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_advance(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_advance(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_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 bounds;
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 (!xa_is_node(entry))
return entry;
xas->xa_node = xa_to_node(entry);
xas_set_offset(xas);
}
out:
if (!max)
goto max;
bounds:
xas->xa_node = XAS_BOUNDS;
return NULL;
max:
xas->xa_node = XAS_RESTART;
return NULL;
}
EXPORT_SYMBOL_GPL(xas_find_marked);
/** /**
* xa_init_flags() - Initialise an empty XArray with flags. * xa_init_flags() - Initialise an empty XArray with flags.
* @xa: XArray. * @xa: XArray.
@ -1152,6 +1359,91 @@ void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
} }
EXPORT_SYMBOL(xa_clear_mark); 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);
/**
* 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;
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.xa_shift) {
if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
continue;
} else {
if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))
continue;
}
if (!xas_retry(&xas, entry))
break;
}
rcu_read_unlock();
if (entry)
*indexp = xas.xa_index;
return entry;
}
EXPORT_SYMBOL(xa_find_after);
#ifdef XA_DEBUG #ifdef XA_DEBUG
void xa_dump_node(const struct xa_node *node) void xa_dump_node(const struct xa_node *node)
{ {