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FROMGIT: maple_tree: try harder to keep active node after mas_next()

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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).

Link: https://lkml.kernel.org/r/20230518145544.1722059-24-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: David Binderman <dcb314@hotmail.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Vernon Yang <vernon2gm@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit f7741cbb138e4cd8586e45806313561cec44f9b6
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-unstable)

Bug: 274059236
Change-Id: I61c7e9e1575b5f5400f9fc2eec08ae4a1eaefa5e
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Liam R. Howlett 2023-05-18 10:55:32 -04:00 • committed by Suren Baghdasaryan
parent 5ff9438fe1
commit cb6d9fa6ad
1 changed files with 48 additions and 43 deletions
Download patch file Download diff file Expand all files Collapse all files

91
lib/maple_tree.c
View file

@ -4754,33 +4754,25 @@ 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;
}
@ -4813,21 +4805,15 @@ retry:
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++;
@ -4846,12 +4832,10 @@ retry:
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;
@ -4861,9 +4845,6 @@ next_node:
mt = mte_node_type(mas->node);
}
mas->index = mas->last = limit;
mas->offset = offset;
mas->node = prev_node;
return NULL;
}
@ -5998,6 +5979,8 @@ 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;
@ -6005,16 +5988,16 @@ 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);
}
@ -6138,17 +6121,25 @@ EXPORT_SYMBOL_GPL(mas_pause);
*/
void *mas_find(struct ma_state *mas, unsigned long max)
{
if (unlikely(mas_is_paused(mas))) {
if (unlikely(mas->last == ULONG_MAX)) {
mas->node = MAS_NONE;
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 >= 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 */
@ -6160,13 +6151,27 @@ 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);
@ -6597,7 +6602,7 @@ retry:
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;