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rhashtable: Enable context analysis

Browse source 
Enable context analysis for rhashtable, which was used as an initial
test as it contains a combination of RCU, mutex, and bit_spinlock usage.

Users of rhashtable now also benefit from annotations on the API, which
will now warn if the RCU read lock is not held where required.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-33-elver@google.com
This commit is contained in:
Marco Elver 2025-12-19 16:40:21 +01:00 • committed by Peter Zijlstra
parent c3d3023f1c
commit 322366b8f1
3 changed files with 18 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

16
include/linux/rhashtable.h
View file

@ -245,16 +245,17 @@ void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
void rhashtable_walk_enter(struct rhashtable *ht,
struct rhashtable_iter *iter);
void rhashtable_walk_exit(struct rhashtable_iter *iter);
int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU);
int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires_shared(RCU);
static inline void rhashtable_walk_start(struct rhashtable_iter *iter)
__acquires_shared(RCU)
{
(void)rhashtable_walk_start_check(iter);
}
void *rhashtable_walk_next(struct rhashtable_iter *iter);
void *rhashtable_walk_peek(struct rhashtable_iter *iter);
void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases_shared(RCU);
void rhashtable_free_and_destroy(struct rhashtable *ht,
void (*free_fn)(void *ptr, void *arg),
@ -325,6 +326,7 @@ static inline struct rhash_lock_head __rcu **rht_bucket_insert(
static inline unsigned long rht_lock(struct bucket_table *tbl,
struct rhash_lock_head __rcu **bkt)
__acquires(__bitlock(0, bkt))
{
unsigned long flags;
@ -337,6 +339,7 @@ static inline unsigned long rht_lock(struct bucket_table *tbl,
static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
struct rhash_lock_head __rcu **bucket,
unsigned int subclass)
__acquires(__bitlock(0, bucket))
{
unsigned long flags;
@ -349,6 +352,7 @@ static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
static inline void rht_unlock(struct bucket_table *tbl,
struct rhash_lock_head __rcu **bkt,
unsigned long flags)
__releases(__bitlock(0, bkt))
{
lock_map_release(&tbl->dep_map);
bit_spin_unlock(0, (unsigned long *)bkt);
@ -424,13 +428,14 @@ static inline void rht_assign_unlock(struct bucket_table *tbl,
struct rhash_lock_head __rcu **bkt,
struct rhash_head *obj,
unsigned long flags)
__releases(__bitlock(0, bkt))
{
if (rht_is_a_nulls(obj))
obj = NULL;
lock_map_release(&tbl->dep_map);
rcu_assign_pointer(*bkt, (void *)obj);
preempt_enable();
__release(bitlock);
__release(__bitlock(0, bkt));
local_irq_restore(flags);
}
@ -612,6 +617,7 @@ static __always_inline struct rhash_head *__rhashtable_lookup(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params,
const enum rht_lookup_freq freq)
__must_hold_shared(RCU)
{
struct rhashtable_compare_arg arg = {
.ht = ht,
@ -666,6 +672,7 @@ restart:
static __always_inline void *rhashtable_lookup(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
__must_hold_shared(RCU)
{
struct rhash_head *he = __rhashtable_lookup(ht, key, params,
RHT_LOOKUP_NORMAL);
@ -676,6 +683,7 @@ static __always_inline void *rhashtable_lookup(
static __always_inline void *rhashtable_lookup_likely(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
__must_hold_shared(RCU)
{
struct rhash_head *he = __rhashtable_lookup(ht, key, params,
RHT_LOOKUP_LIKELY);
@ -727,6 +735,7 @@ static __always_inline void *rhashtable_lookup_fast(
static __always_inline struct rhlist_head *rhltable_lookup(
struct rhltable *hlt, const void *key,
const struct rhashtable_params params)
__must_hold_shared(RCU)
{
struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params,
RHT_LOOKUP_NORMAL);
@ -737,6 +746,7 @@ static __always_inline struct rhlist_head *rhltable_lookup(
static __always_inline struct rhlist_head *rhltable_lookup_likely(
struct rhltable *hlt, const void *key,
const struct rhashtable_params params)
__must_hold_shared(RCU)
{
struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params,
RHT_LOOKUP_LIKELY);

2
lib/Makefile
View file

@ -50,6 +50,8 @@ lib-$(CONFIG_MIN_HEAP) += min_heap.o
lib-y += kobject.o klist.o
obj-y += lockref.o
CONTEXT_ANALYSIS_rhashtable.o := y
obj-y += bcd.o sort.o parser.o debug_locks.o random32.o \
bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
list_sort.o uuid.o iov_iter.o clz_ctz.o \

5
lib/rhashtable.c
View file

@ -358,6 +358,7 @@ static int rhashtable_rehash_table(struct rhashtable *ht)
static int rhashtable_rehash_alloc(struct rhashtable *ht,
struct bucket_table *old_tbl,
unsigned int size)
__must_hold(&ht->mutex)
{
struct bucket_table *new_tbl;
int err;
@ -392,6 +393,7 @@ static int rhashtable_rehash_alloc(struct rhashtable *ht,
* bucket locks or concurrent RCU protected lookups and traversals.
*/
static int rhashtable_shrink(struct rhashtable *ht)
__must_hold(&ht->mutex)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
unsigned int nelems = atomic_read(&ht->nelems);
@ -724,7 +726,7 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
* resize events and always continue.
*/
int rhashtable_walk_start_check(struct rhashtable_iter *iter)
__acquires(RCU)
__acquires_shared(RCU)
{
struct rhashtable *ht = iter->ht;
bool rhlist = ht->rhlist;
@ -940,7 +942,6 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_peek);
* hash table.
*/
void rhashtable_walk_stop(struct rhashtable_iter *iter)
__releases(RCU)
{
struct rhashtable *ht;
struct bucket_table *tbl = iter->walker.tbl;