The patch titled
Subject: maple_tree: Be more strict about locking
has been added to the -mm mm-unstable branch. Its filename is
maple_tree-be-more-strict-about-locking.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-be-more-strict-about-locking.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Subject: maple_tree: Be more strict about locking
Date: Fri, 14 Jul 2023 15:55:51 -0400
Use lockdep to check the write path in the maple tree holds the lock in
write mode.
Introduce mt_write_lock_is_held() to check if the lock is held for
writing. Update the necessary checks for rcu_dereference_protected() to
use the new write lock check.
Link: https://lkml.kernel.org/r/20230714195551.894800-5-Liam.Howlett@xxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Oliver Sang <oliver.sang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/maple_tree.h | 7 ++++++-
lib/maple_tree.c | 10 ++++++++--
2 files changed, 14 insertions(+), 3 deletions(-)
--- a/include/linux/maple_tree.h~maple_tree-be-more-strict-about-locking
+++ a/include/linux/maple_tree.h
@@ -185,13 +185,18 @@ typedef struct lockdep_map *lockdep_map_
#define mt_lock_is_held(mt) \
(!(mt)->ma_external_lock || lock_is_held((mt)->ma_external_lock))
+#define mt_write_lock_is_held(mt) \
+ (!(mt)->ma_external_lock || \
+ lock_is_held_type((mt)->ma_external_lock, 0))
+
#define mt_set_external_lock(mt, lock) \
(mt)->ma_external_lock = &(lock)->dep_map
#define mt_on_stack(mt) (mt).ma_external_lock = NULL
#else
typedef struct { /* nothing */ } lockdep_map_p;
-#define mt_lock_is_held(mt) 1
+#define mt_lock_is_held(mt) 1
+#define mt_write_lock_is_held(mt) 1
#define mt_set_external_lock(mt, lock) do { } while (0)
#define mt_on_stack(mt) do { } while (0)
#endif
--- a/lib/maple_tree.c~maple_tree-be-more-strict-about-locking
+++ a/lib/maple_tree.c
@@ -777,6 +777,12 @@ static inline void __rcu **ma_slots(stru
}
}
+static inline bool mt_write_locked(const struct maple_tree *mt)
+{
+ return mt_external_lock(mt) ? mt_write_lock_is_held(mt) :
+ lockdep_is_held(&mt->ma_lock);
+}
+
static inline bool mt_locked(const struct maple_tree *mt)
{
return mt_external_lock(mt) ? mt_lock_is_held(mt) :
@@ -792,7 +798,7 @@ static inline void *mt_slot(const struct
static inline void *mt_slot_locked(struct maple_tree *mt, void __rcu **slots,
unsigned char offset)
{
- return rcu_dereference_protected(slots[offset], mt_locked(mt));
+ return rcu_dereference_protected(slots[offset], mt_write_locked(mt));
}
/*
* mas_slot_locked() - Get the slot value when holding the maple tree lock.
@@ -835,7 +841,7 @@ static inline void *mas_root(struct ma_s
static inline void *mt_root_locked(struct maple_tree *mt)
{
- return rcu_dereference_protected(mt->ma_root, mt_locked(mt));
+ return rcu_dereference_protected(mt->ma_root, mt_write_locked(mt));
}
/*
_
Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are
mm-mmap-clean-up-validate_mm-calls.patch
maple_tree-relax-lockdep-checks-for-on-stack-trees.patch
mm-mmap-change-detached-vma-locking-scheme.patch
maple_tree-be-more-strict-about-locking.patch
