lkml.org 
[lkml]   [2018]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v9 21/61] xarray: Add xas_next and xas_prev
Date
From: Matthew Wilcox <mawilcox@microsoft.com>

These two functions move the xas index by one position, and adjust the
rest of the iterator state to match it. This is more efficient than
calling xas_set() as it keeps the iterator at the leaves of the tree
instead of walking the iterator from the root each time.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
include/linux/xarray.h | 67 +++++++++
lib/xarray.c | 74 ++++++++++
tools/testing/radix-tree/xarray-test.c | 261 ++++++++++++++++++++++++++++++++-
3 files changed, 401 insertions(+), 1 deletion(-)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 96773f83ae03..c8a0ddc1b3df 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -683,6 +683,12 @@ static inline bool xas_not_node(struct xa_node *node)
return ((unsigned long)node & 3) || !node;
}

+/* True if the node represents RESTART or an error */
+static inline bool xas_frozen(struct xa_node *node)
+{
+ return (unsigned long)node & 2;
+}
+
/* True if the node represents head-of-tree, RESTART or BOUNDS */
static inline bool xas_top(struct xa_node *node)
{
@@ -940,6 +946,67 @@ enum {
for (entry = xas_find_tag(xas, max, tag); entry; \
entry = xas_next_tag(xas, max, tag))

+void *__xas_next(struct xa_state *);
+void *__xas_prev(struct xa_state *);
+
+/**
+ * xas_prev() - Move iterator to previous index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL. If the @xas has never been walked,
+ * it will have the effect of calling xas_load(). Otherwise one will be
+ * subtracted from the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index 0, this function wraps
+ * around to %ULONG_MAX.
+ *
+ * Return: The entry at the new index. This may be %NULL or an internal
+ * entry, although it should never be a node entry.
+ */
+static inline void *xas_prev(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_node;
+
+ if (unlikely(xas_not_node(node) || node->shift ||
+ xas->xa_offset == 0))
+ return __xas_prev(xas);
+
+ xas->xa_index--;
+ xas->xa_offset--;
+ return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
+/**
+ * xas_next() - Move state to next index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL. If the @xas has never been walked,
+ * it will have the effect of calling xas_load(). Otherwise one will be
+ * added to the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index %ULONG_MAX, this function wraps
+ * around to 0.
+ *
+ * Return: The entry at the new index. This may be %NULL or an internal
+ * entry, although it should never be a node entry.
+ */
+static inline void *xas_next(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_node;
+
+ if (unlikely(xas_not_node(node) || node->shift ||
+ xas->xa_offset == XA_CHUNK_MASK))
+ return __xas_next(xas);
+
+ xas->xa_index++;
+ xas->xa_offset++;
+ return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
/* Internal functions, mostly shared between radix-tree.c, xarray.c and idr.c */
void xas_destroy(struct xa_state *);

diff --git a/lib/xarray.c b/lib/xarray.c
index 080ed0fc3feb..7cf195b6e740 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -838,6 +838,80 @@ void xas_pause(struct xa_state *xas)
}
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_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_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.
diff --git a/tools/testing/radix-tree/xarray-test.c b/tools/testing/radix-tree/xarray-test.c
index 0392b0ae81fe..83fe6c6213e8 100644
--- a/tools/testing/radix-tree/xarray-test.c
+++ b/tools/testing/radix-tree/xarray-test.c
@@ -42,6 +42,147 @@ void check_xa_tag(struct xarray *xa)
assert(xa_get_tag(xa, 0, XA_TAG_0) == false);
}

+/* Check that putting the xas into an error state works correctly */
+void check_xas_error(struct xarray *xa)
+{
+ XA_STATE(xas, xa, 0);
+
+ assert(xa_store(xa, 1, xa_mk_value(1), GFP_KERNEL) == 0);
+ assert(xa_load(xa, 1) == xa_mk_value(1));
+
+ assert(xas_error(&xas) == 0);
+
+ xas_set_err(&xas, -ENOTTY);
+ assert(xas_error(&xas) == -ENOTTY);
+
+ xas_set_err(&xas, -ENOSPC);
+ assert(xas_error(&xas) == -ENOSPC);
+
+ xas_set_err(&xas, -ENOMEM);
+ assert(xas_error(&xas) == -ENOMEM);
+
+ assert(xas_load(&xas) == NULL);
+ assert(xas_store(&xas, &xas) == NULL);
+ assert(xas_load(&xas) == NULL);
+
+ assert(xas.xa_index == 0);
+ assert(xas_next(&xas) == NULL);
+ assert(xas.xa_index == 0);
+
+ assert(xas_prev(&xas) == NULL);
+ assert(xas.xa_index == 0);
+
+ xas_retry(&xas, XA_RETRY_ENTRY);
+ assert(xas_error(&xas) == 0);
+
+ assert(xas_find(&xas, ULONG_MAX) == xa_mk_value(1));
+ assert(xas.xa_index == 1);
+ assert(xas_error(&xas) == 0);
+
+ assert(xas_find(&xas, ULONG_MAX) == NULL);
+ assert(xas.xa_index > 1);
+ assert(xas_error(&xas) == 0);
+ assert(xas.xa_node == XAS_BOUNDS);
+}
+
+void check_xas_pause(struct xarray *xa)
+{
+ XA_STATE(xas, xa, 0);
+ void *entry;
+ unsigned int seen;
+
+ xa_store(xa, 0, xa_mk_value(0), GFP_KERNEL);
+ xa_set_tag(xa, 0, XA_TAG_0);
+
+ seen = 0;
+ rcu_read_lock();
+ xas_for_each_tag(&xas, entry, ULONG_MAX, XA_TAG_0) {
+ if (!seen++) {
+ xa_store(xa, 1, xa_mk_value(1), GFP_KERNEL);
+ xa_set_tag(xa, 1, XA_TAG_0);
+ }
+ }
+ rcu_read_unlock();
+ /* We don't see an entry that was added after we started */
+ assert(seen == 1);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ rcu_read_lock();
+ xas_for_each_tag(&xas, entry, ULONG_MAX, XA_TAG_0) {
+ if (!seen++)
+ xa_erase(xa, 1);
+ }
+ rcu_read_unlock();
+ assert(seen == 1);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ rcu_read_lock();
+ xas_for_each(&xas, entry, ULONG_MAX) {
+ if (!seen++)
+ xa_store(xa, 1, xa_mk_value(1), GFP_KERNEL);
+ }
+ rcu_read_unlock();
+ assert(seen == 1);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ rcu_read_lock();
+ xas_for_each(&xas, entry, ULONG_MAX) {
+ if (!seen++)
+ xa_erase(xa, 1);
+ }
+ rcu_read_unlock();
+ assert(seen == 1);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ rcu_read_lock();
+ for (entry = xas_load(&xas); entry; entry = xas_next(&xas)) {
+ if (!seen++)
+ xa_store(xa, 1, xa_mk_value(1), GFP_KERNEL);
+ }
+ rcu_read_unlock();
+ assert(seen == 2);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ rcu_read_lock();
+ for (entry = xas_load(&xas); entry; entry = xas_next(&xas)) {
+ if (!seen++)
+ xa_erase(xa, 1);
+ }
+ rcu_read_unlock();
+ assert(seen == 1);
+
+ xa_store(xa, 1, xa_mk_value(1), GFP_KERNEL);
+ seen = 0;
+ xas_set(&xas, 0);
+ xas_for_each(&xas, entry, ULONG_MAX) {
+ if (!seen++)
+ xas_pause(&xas);
+ }
+ assert(seen == 2);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ for (entry = xas_load(&xas); entry; entry = xas_next(&xas)) {
+ if (!seen++)
+ xas_pause(&xas);
+ }
+ assert(seen == 2);
+
+ seen = 0;
+ xas_set(&xas, 0);
+ xa_set_tag(xa, 1, XA_TAG_0);
+ xas_for_each_tag(&xas, entry, ULONG_MAX, XA_TAG_0) {
+ if (!seen++)
+ xas_pause(&xas);
+ }
+ assert(seen == 2);
+}
+
void check_xas_retry(struct xarray *xa)
{
XA_STATE(xas, xa, 0);
@@ -54,7 +195,7 @@ void check_xas_retry(struct xarray *xa)
assert(xa_is_retry(xas_reload(&xas)));
assert(!xas_retry(&xas, NULL));
assert(!xas_retry(&xas, xa_mk_value(0)));
- assert(xas_retry(&xas, XA_RETRY_ENTRY));
+ xas_reset(&xas);
assert(xas.xa_node == XAS_RESTART);
assert(xas_next_entry(&xas, ULONG_MAX) == xa_mk_value(0));
assert(xas.xa_node == NULL);
@@ -250,9 +391,108 @@ void check_xas_delete(struct xarray *xa)
}
}

+void check_move_small(struct xarray *xa, unsigned long idx)
+{
+ XA_STATE(xas, xa, 0);
+ unsigned long i;
+
+ xa_store(xa, 0, xa_mk_value(0), GFP_KERNEL);
+ xa_store(xa, idx, xa_mk_value(idx), GFP_KERNEL);
+
+ for (i = 0; i < idx * 4; i++) {
+ void *entry = xas_next(&xas);
+ if (i <= idx)
+ assert(xas.xa_node != XAS_RESTART);
+ assert(xas.xa_index == i);
+ if (i == 0 || i == idx)
+ assert(entry == xa_mk_value(i));
+ else
+ assert(entry == NULL);
+ }
+ xas_next(&xas);
+ assert(xas.xa_index == i);
+
+ do {
+ void *entry = xas_prev(&xas);
+ i--;
+ if (i <= idx)
+ assert(xas.xa_node != XAS_RESTART);
+ assert(xas.xa_index == i);
+ if (i == 0 || i == idx)
+ assert(entry == xa_mk_value(i));
+ else
+ assert(entry == NULL);
+ } while (i > 0);
+
+ xas_set(&xas, ULONG_MAX);
+ assert(xas_next(&xas) == NULL);
+ assert(xas.xa_index == ULONG_MAX);
+ assert(xas_next(&xas) == xa_mk_value(0));
+ assert(xas.xa_index == 0);
+ assert(xas_prev(&xas) == NULL);
+ assert(xas.xa_index == ULONG_MAX);
+}
+
+void check_move(struct xarray *xa)
+{
+ XA_STATE(xas, xa, (1 << 16) - 1);
+ unsigned long i;
+
+ for (i = 0; i < (1 << 16); i++) {
+ xa_store(xa, i, xa_mk_value(i), GFP_KERNEL);
+ }
+
+ do {
+ void *entry = xas_prev(&xas);
+ i--;
+ assert(entry == xa_mk_value(i));
+ assert(i == xas.xa_index);
+ } while (i != 0);
+
+ assert(xas_prev(&xas) == NULL);
+ assert(xas.xa_index == ULONG_MAX);
+
+ do {
+ void *entry = xas_next(&xas);
+ assert(entry == xa_mk_value(i));
+ assert(i == xas.xa_index);
+ i++;
+ } while (i < (1 << 16));
+
+ for (i = (1 << 8); i < (1 << 15); i++) {
+ xa_erase(xa, i);
+ }
+
+ i = xas.xa_index;
+
+ do {
+ void *entry = xas_prev(&xas);
+ i--;
+ if ((i < (1 << 8)) || (i >= (1 << 15)))
+ assert(entry == xa_mk_value(i));
+ else
+ assert(entry == NULL);
+ assert(i == xas.xa_index);
+ } while (i != 0);
+
+ assert(xas_prev(&xas) == NULL);
+ assert(xas.xa_index == ULONG_MAX);
+
+ do {
+ void *entry = xas_next(&xas);
+ if ((i < (1 << 8)) || (i >= (1 << 15)))
+ assert(entry == xa_mk_value(i));
+ else
+ assert(entry == NULL);
+ assert(i == xas.xa_index);
+ i++;
+ } while (i < (1 << 16));
+}
+
void xarray_checks(void)
{
DEFINE_XARRAY(array);
+ unsigned long i;

check_xa_err(&array);
item_kill_tree(&array);
@@ -260,9 +500,15 @@ void xarray_checks(void)
check_xa_tag(&array);
item_kill_tree(&array);

+ check_xas_error(&array);
+ item_kill_tree(&array);
+
check_xas_retry(&array);
item_kill_tree(&array);

+ check_xas_pause(&array);
+ item_kill_tree(&array);
+
check_xa_load(&array);
item_kill_tree(&array);

@@ -276,6 +522,19 @@ void xarray_checks(void)
check_find(&array);
check_xas_delete(&array);
item_kill_tree(&array);
+
+ for (i = 0; i < 16; i++) {
+ check_move_small(&array, 1UL << i);
+ item_kill_tree(&array);
+ }
+
+ for (i = 2; i < 16; i++) {
+ check_move_small(&array, (1UL << i) - 1);
+ item_kill_tree(&array);
+ }
+
+ check_move(&array);
+ item_kill_tree(&array);
}

int __weak main(void)
--
2.16.1
\
 
 \ /
  Last update: 2018-03-13 14:46    [W:0.226 / U:0.576 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site