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Message-Id: <20230518145544.1722059-24-Liam.Howlett@oracle.com>
Date: Thu, 18 May 2023 10:55:32 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: maple-tree@...ts.infradead.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
"Liam R. Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH v4 23/35] maple_tree: Try harder to keep active node after mas_next()
Clean up the mas_next() call to try and keep a node reference when
possible. This will avoid re-walking the tree in most cases.
Also clean up the single entry tree handling to ensure index/last are
consistent with what one would expect. (returning NULL with limit of
1-oo).
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
lib/maple_tree.c | 89 +++++++++++++++++++++++++-----------------------
1 file changed, 47 insertions(+), 42 deletions(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index e233f41ed4da..09142af08214 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4726,33 +4726,25 @@ static inline void *mas_next_nentry(struct ma_state *mas,
if (ma_dead_node(node))
return NULL;
+ mas->last = pivot;
if (entry)
- goto found;
+ return entry;
if (pivot >= max)
return NULL;
+ if (pivot >= mas->max)
+ return NULL;
+
mas->index = pivot + 1;
mas->offset++;
}
- if (mas->index > mas->max) {
- mas->index = mas->last;
- return NULL;
- }
-
- pivot = mas_safe_pivot(mas, pivots, mas->offset, type);
+ pivot = mas_logical_pivot(mas, pivots, mas->offset, type);
entry = mas_slot(mas, slots, mas->offset);
if (ma_dead_node(node))
return NULL;
- if (!pivot)
- return NULL;
-
- if (!entry)
- return NULL;
-
-found:
mas->last = pivot;
return entry;
}
@@ -4781,21 +4773,15 @@ static inline void mas_rewalk(struct ma_state *mas, unsigned long index)
static inline void *mas_next_entry(struct ma_state *mas, unsigned long limit)
{
void *entry = NULL;
- struct maple_enode *prev_node;
struct maple_node *node;
- unsigned char offset;
unsigned long last;
enum maple_type mt;
- if (mas->index > limit) {
- mas->index = mas->last = limit;
- mas_pause(mas);
+ if (mas->last >= limit)
return NULL;
- }
+
last = mas->last;
retry:
- offset = mas->offset;
- prev_node = mas->node;
node = mas_mn(mas);
mt = mte_node_type(mas->node);
mas->offset++;
@@ -4814,12 +4800,10 @@ static inline void *mas_next_entry(struct ma_state *mas, unsigned long limit)
if (likely(entry))
return entry;
- if (unlikely((mas->index > limit)))
- break;
+ if (unlikely((mas->last >= limit)))
+ return NULL;
next_node:
- prev_node = mas->node;
- offset = mas->offset;
if (unlikely(mas_next_node(mas, node, limit))) {
mas_rewalk(mas, last);
goto retry;
@@ -4829,9 +4813,6 @@ static inline void *mas_next_entry(struct ma_state *mas, unsigned long limit)
mt = mte_node_type(mas->node);
}
- mas->index = mas->last = limit;
- mas->offset = offset;
- mas->node = prev_node;
return NULL;
}
@@ -5919,6 +5900,8 @@ EXPORT_SYMBOL_GPL(mas_expected_entries);
*/
void *mas_next(struct ma_state *mas, unsigned long max)
{
+ bool was_none = mas_is_none(mas);
+
if (mas_is_none(mas) || mas_is_paused(mas))
mas->node = MAS_START;
@@ -5926,16 +5909,16 @@ void *mas_next(struct ma_state *mas, unsigned long max)
mas_walk(mas); /* Retries on dead nodes handled by mas_walk */
if (mas_is_ptr(mas)) {
- if (!mas->index) {
- mas->index = 1;
- mas->last = ULONG_MAX;
+ if (was_none && mas->index == 0) {
+ mas->index = mas->last = 0;
+ return mas_root(mas);
}
+ mas->index = 1;
+ mas->last = ULONG_MAX;
+ mas->node = MAS_NONE;
return NULL;
}
- if (mas->last == ULONG_MAX)
- return NULL;
-
/* Retries on dead nodes handled by mas_next_entry */
return mas_next_entry(mas, max);
}
@@ -6059,17 +6042,25 @@ EXPORT_SYMBOL_GPL(mas_pause);
*/
void *mas_find(struct ma_state *mas, unsigned long max)
{
+ if (unlikely(mas_is_none(mas))) {
+ if (unlikely(mas->last >= max))
+ return NULL;
+
+ mas->index = mas->last;
+ mas->node = MAS_START;
+ }
+
if (unlikely(mas_is_paused(mas))) {
- if (unlikely(mas->last == ULONG_MAX)) {
- mas->node = MAS_NONE;
+ if (unlikely(mas->last >= max))
return NULL;
- }
+
mas->node = MAS_START;
mas->index = ++mas->last;
}
- if (unlikely(mas_is_none(mas)))
- mas->node = MAS_START;
+
+ if (unlikely(mas_is_ptr(mas)))
+ goto ptr_out_of_range;
if (unlikely(mas_is_start(mas))) {
/* First run or continue */
@@ -6081,13 +6072,27 @@ void *mas_find(struct ma_state *mas, unsigned long max)
entry = mas_walk(mas);
if (entry)
return entry;
+
}
- if (unlikely(!mas_searchable(mas)))
+ if (unlikely(!mas_searchable(mas))) {
+ if (unlikely(mas_is_ptr(mas)))
+ goto ptr_out_of_range;
+
+ return NULL;
+ }
+
+ if (mas->index == max)
return NULL;
/* Retries on dead nodes handled by mas_next_entry */
return mas_next_entry(mas, max);
+
+ptr_out_of_range:
+ mas->node = MAS_NONE;
+ mas->index = 1;
+ mas->last = ULONG_MAX;
+ return NULL;
}
EXPORT_SYMBOL_GPL(mas_find);
@@ -6518,7 +6523,7 @@ void *mt_find(struct maple_tree *mt, unsigned long *index, unsigned long max)
if (entry)
goto unlock;
- while (mas_searchable(&mas) && (mas.index < max)) {
+ while (mas_searchable(&mas) && (mas.last < max)) {
entry = mas_next_entry(&mas, max);
if (likely(entry && !xa_is_zero(entry)))
break;
--
2.39.2
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