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radix-tree: Fix __rcu annotations
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Many places were missing __rcu annotations.  A few places needed a few
lines of explanation about why it was safe to not use RCU accessors.
Add a custom CFLAGS setting to the Makefile to ensure that new patches
don't miss RCU annotations.

Signed-off-by: Matthew Wilcox <[email protected]>
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Matthew Wilcox committed Feb 14, 2017
1 parent 12320d0 commit d7b6272
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Showing 3 changed files with 122 additions and 115 deletions.
110 changes: 54 additions & 56 deletions include/linux/radix-tree.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -221,37 +221,36 @@ static inline unsigned int iter_shift(const struct radix_tree_iter *iter)
*/

/**
* radix_tree_deref_slot - dereference a slot
* @pslot: pointer to slot, returned by radix_tree_lookup_slot
* Returns: item that was stored in that slot with any direct pointer flag
* removed.
* radix_tree_deref_slot - dereference a slot
* @slot: slot pointer, returned by radix_tree_lookup_slot
*
* For use with radix_tree_lookup_slot(). Caller must hold tree at least read
* locked across slot lookup and dereference. Not required if write lock is
* held (ie. items cannot be concurrently inserted).
*
* radix_tree_deref_retry must be used to confirm validity of the pointer if
* only the read lock is held.
*
* Return: entry stored in that slot.
*/
static inline void *radix_tree_deref_slot(void **pslot)
static inline void *radix_tree_deref_slot(void __rcu **slot)
{
return rcu_dereference(*pslot);
return rcu_dereference(*slot);
}

/**
* radix_tree_deref_slot_protected - dereference a slot without RCU lock but with tree lock held
* @pslot: pointer to slot, returned by radix_tree_lookup_slot
* Returns: item that was stored in that slot with any direct pointer flag
* removed.
*
* Similar to radix_tree_deref_slot but only used during migration when a pages
* mapping is being moved. The caller does not hold the RCU read lock but it
* must hold the tree lock to prevent parallel updates.
* radix_tree_deref_slot_protected - dereference a slot with tree lock held
* @slot: slot pointer, returned by radix_tree_lookup_slot
*
* Similar to radix_tree_deref_slot. The caller does not hold the RCU read
* lock but it must hold the tree lock to prevent parallel updates.
*
* Return: entry stored in that slot.
*/
static inline void *radix_tree_deref_slot_protected(void **pslot,
static inline void *radix_tree_deref_slot_protected(void __rcu **slot,
spinlock_t *treelock)
{
return rcu_dereference_protected(*pslot, lockdep_is_held(treelock));
return rcu_dereference_protected(*slot, lockdep_is_held(treelock));
}

/**
Expand Down Expand Up @@ -287,9 +286,9 @@ static inline int radix_tree_exception(void *arg)
return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK);
}

int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
int __radix_tree_create(struct radix_tree_root *, unsigned long index,
unsigned order, struct radix_tree_node **nodep,
void ***slotp);
void __rcu ***slotp);
int __radix_tree_insert(struct radix_tree_root *, unsigned long index,
unsigned order, void *);
static inline int radix_tree_insert(struct radix_tree_root *root,
Expand All @@ -298,58 +297,55 @@ static inline int radix_tree_insert(struct radix_tree_root *root,
return __radix_tree_insert(root, index, 0, entry);
}
void *__radix_tree_lookup(const struct radix_tree_root *, unsigned long index,
struct radix_tree_node **nodep, void ***slotp);
struct radix_tree_node **nodep, void __rcu ***slotp);
void *radix_tree_lookup(const struct radix_tree_root *, unsigned long);
void **radix_tree_lookup_slot(const struct radix_tree_root *, unsigned long);
void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *,
unsigned long index);
typedef void (*radix_tree_update_node_t)(struct radix_tree_node *, void *);
void __radix_tree_replace(struct radix_tree_root *root,
struct radix_tree_node *node,
void **slot, void *item,
void __radix_tree_replace(struct radix_tree_root *, struct radix_tree_node *,
void __rcu **slot, void *entry,
radix_tree_update_node_t update_node, void *private);
void radix_tree_iter_replace(struct radix_tree_root *,
const struct radix_tree_iter *, void **slot, void *item);
void radix_tree_replace_slot(struct radix_tree_root *root,
void **slot, void *item);
void __radix_tree_delete_node(struct radix_tree_root *root,
struct radix_tree_node *node,
const struct radix_tree_iter *, void __rcu **slot, void *entry);
void radix_tree_replace_slot(struct radix_tree_root *,
void __rcu **slot, void *entry);
void __radix_tree_delete_node(struct radix_tree_root *,
struct radix_tree_node *,
radix_tree_update_node_t update_node,
void *private);
void radix_tree_iter_delete(struct radix_tree_root *,
struct radix_tree_iter *iter, void **slot);
struct radix_tree_iter *iter, void __rcu **slot);
void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
void radix_tree_clear_tags(struct radix_tree_root *root,
struct radix_tree_node *node,
void **slot);
void radix_tree_clear_tags(struct radix_tree_root *, struct radix_tree_node *,
void __rcu **slot);
unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
void **results, unsigned long first_index,
unsigned int max_items);
unsigned int radix_tree_gang_lookup_slot(const struct radix_tree_root *,
void ***results, unsigned long *indices,
void __rcu ***results, unsigned long *indices,
unsigned long first_index, unsigned int max_items);
int radix_tree_preload(gfp_t gfp_mask);
int radix_tree_maybe_preload(gfp_t gfp_mask);
int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order);
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *root,
void *radix_tree_tag_set(struct radix_tree_root *,
unsigned long index, unsigned int tag);
void *radix_tree_tag_clear(struct radix_tree_root *root,
void *radix_tree_tag_clear(struct radix_tree_root *,
unsigned long index, unsigned int tag);
int radix_tree_tag_get(const struct radix_tree_root *,
unsigned long index, unsigned int tag);
void radix_tree_iter_tag_set(struct radix_tree_root *,
const struct radix_tree_iter *iter, unsigned int tag);
void radix_tree_iter_tag_clear(struct radix_tree_root *,
const struct radix_tree_iter *iter, unsigned int tag);
unsigned int
radix_tree_gang_lookup_tag(const struct radix_tree_root *, void **results,
unsigned long first_index, unsigned int max_items,
unsigned int tag);
unsigned int
radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *, void ***results,
unsigned long first_index, unsigned int max_items,
unsigned int tag);
int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag);
unsigned int radix_tree_gang_lookup_tag(const struct radix_tree_root *,
void **results, unsigned long first_index,
unsigned int max_items, unsigned int tag);
unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *,
void __rcu ***results, unsigned long first_index,
unsigned int max_items, unsigned int tag);
int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag);

static inline void radix_tree_preload_end(void)
{
Expand All @@ -361,7 +357,7 @@ int radix_tree_split(struct radix_tree_root *, unsigned long index,
unsigned new_order);
int radix_tree_join(struct radix_tree_root *, unsigned long index,
unsigned new_order, void *);
void **idr_get_free(struct radix_tree_root *, struct radix_tree_iter *,
void __rcu **idr_get_free(struct radix_tree_root *, struct radix_tree_iter *,
gfp_t, int end);

enum {
Expand All @@ -377,7 +373,7 @@ enum {
* @start: iteration starting index
* Returns: NULL
*/
static __always_inline void **
static __always_inline void __rcu **
radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
{
/*
Expand Down Expand Up @@ -406,7 +402,7 @@ radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
* Also it fills @iter with data about chunk: position in the tree (index),
* its end (next_index), and constructs a bit mask for tagged iterating (tags).
*/
void **radix_tree_next_chunk(const struct radix_tree_root *,
void __rcu **radix_tree_next_chunk(const struct radix_tree_root *,
struct radix_tree_iter *iter, unsigned flags);

/**
Expand All @@ -419,7 +415,8 @@ void **radix_tree_next_chunk(const struct radix_tree_root *,
* containing it and updates @iter to describe the entry. If @index is not
* present, it returns NULL.
*/
static inline void **radix_tree_iter_lookup(const struct radix_tree_root *root,
static inline void __rcu **
radix_tree_iter_lookup(const struct radix_tree_root *root,
struct radix_tree_iter *iter, unsigned long index)
{
radix_tree_iter_init(iter, index);
Expand All @@ -436,7 +433,8 @@ static inline void **radix_tree_iter_lookup(const struct radix_tree_root *root,
* which is at least @index. If @index is larger than any present entry, this
* function returns NULL. The @iter is updated to describe the entry found.
*/
static inline void **radix_tree_iter_find(const struct radix_tree_root *root,
static inline void __rcu **
radix_tree_iter_find(const struct radix_tree_root *root,
struct radix_tree_iter *iter, unsigned long index)
{
radix_tree_iter_init(iter, index);
Expand All @@ -453,7 +451,7 @@ static inline void **radix_tree_iter_find(const struct radix_tree_root *root,
* and continue the iteration.
*/
static inline __must_check
void **radix_tree_iter_retry(struct radix_tree_iter *iter)
void __rcu **radix_tree_iter_retry(struct radix_tree_iter *iter)
{
iter->next_index = iter->index;
iter->tags = 0;
Expand All @@ -476,7 +474,7 @@ __radix_tree_iter_add(struct radix_tree_iter *iter, unsigned long slots)
* have been invalidated by an insertion or deletion. Call this function
* before releasing the lock to continue the iteration from the next index.
*/
void **__must_check radix_tree_iter_resume(void **slot,
void __rcu **__must_check radix_tree_iter_resume(void __rcu **slot,
struct radix_tree_iter *iter);

/**
Expand All @@ -492,11 +490,11 @@ radix_tree_chunk_size(struct radix_tree_iter *iter)
}

#ifdef CONFIG_RADIX_TREE_MULTIORDER
void ** __radix_tree_next_slot(void **slot, struct radix_tree_iter *iter,
unsigned flags);
void __rcu **__radix_tree_next_slot(void __rcu **slot,
struct radix_tree_iter *iter, unsigned flags);
#else
/* Can't happen without sibling entries, but the compiler can't tell that */
static inline void ** __radix_tree_next_slot(void **slot,
static inline void __rcu **__radix_tree_next_slot(void __rcu **slot,
struct radix_tree_iter *iter, unsigned flags)
{
return slot;
Expand All @@ -522,8 +520,8 @@ static inline void ** __radix_tree_next_slot(void **slot,
* b) we are doing non-tagged iteration, and iter->index and iter->next_index
* have been set up so that radix_tree_chunk_size() returns 1 or 0.
*/
static __always_inline void **
radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot,
struct radix_tree_iter *iter, unsigned flags)
{
if (flags & RADIX_TREE_ITER_TAGGED) {
iter->tags >>= 1;
Expand Down
2 changes: 2 additions & 0 deletions lib/Makefile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
earlycpio.o seq_buf.o nmi_backtrace.o nodemask.o win_minmax.o

CFLAGS_radix-tree.o += -DCONFIG_SPARSE_RCU_POINTER

lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
lib-$(CONFIG_HAS_DMA) += dma-noop.o
Expand Down
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