[PATCH 5.7 61/79] rhashtable: Restore RCU marking on rhash_lock_head

Greg Kroah-Hartman
2020-08-10T15:24:51Z

From: Herbert Xu <herbert@gondor.apana.org.au>

[ Upstream commit ce9b362bf6db51a083c4221ef0f93c16cfb1facf ]

This patch restores the RCU marking on bucket_table->buckets as
it really does need RCU protection. Its removal had led to a fatal
bug.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/rhashtable.h | 56 +++++++++++++++++++--------------------------
lib/rhashtable.c | 35 ++++++++++++----------------
2 files changed, 40 insertions(+), 51 deletions(-)

--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -84,7 +84,7 @@ struct bucket_table {

struct lockdep_map dep_map;

- struct rhash_lock_head *buckets[] ____cacheline_aligned_in_smp;
+ struct rhash_lock_head __rcu *buckets[] ____cacheline_aligned_in_smp;
};

/*
@@ -261,13 +261,12 @@ void rhashtable_free_and_destroy(struct
void *arg);
void rhashtable_destroy(struct rhashtable *ht);

-struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl,
- unsigned int hash);
-struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl,
- unsigned int hash);
-struct rhash_lock_head **rht_bucket_nested_insert(struct rhashtable *ht,
- struct bucket_table *tbl,
- unsigned int hash);
+struct rhash_lock_head __rcu **rht_bucket_nested(
+ const struct bucket_table *tbl, unsigned int hash);
+struct rhash_lock_head __rcu **__rht_bucket_nested(
+ const struct bucket_table *tbl, unsigned int hash);
+struct rhash_lock_head __rcu **rht_bucket_nested_insert(
+ struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash);

#define rht_dereference(p, ht) \
rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
@@ -284,21 +283,21 @@ struct rhash_lock_head **rht_bucket_nest
#define rht_entry(tpos, pos, member) \
({ tpos = container_of(pos, typeof(*tpos), member); 1; })

-static inline struct rhash_lock_head *const *rht_bucket(
+static inline struct rhash_lock_head __rcu *const *rht_bucket(
const struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
&tbl->buckets[hash];
}

-static inline struct rhash_lock_head **rht_bucket_var(
+static inline struct rhash_lock_head __rcu **rht_bucket_var(
struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) :
&tbl->buckets[hash];
}

-static inline struct rhash_lock_head **rht_bucket_insert(
+static inline struct rhash_lock_head __rcu **rht_bucket_insert(
struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
@@ -325,7 +324,7 @@ static inline struct rhash_lock_head **r
*/

static inline void rht_lock(struct bucket_table *tbl,
- struct rhash_lock_head **bkt)
+ struct rhash_lock_head __rcu **bkt)
{
local_bh_disable();
bit_spin_lock(0, (unsigned long *)bkt);
@@ -333,7 +332,7 @@ static inline void rht_lock(struct bucke
}

static inline void rht_lock_nested(struct bucket_table *tbl,
- struct rhash_lock_head **bucket,
+ struct rhash_lock_head __rcu **bucket,
unsigned int subclass)
{
local_bh_disable();
@@ -342,7 +341,7 @@ static inline void rht_lock_nested(struc
}

static inline void rht_unlock(struct bucket_table *tbl,
- struct rhash_lock_head **bkt)
+ struct rhash_lock_head __rcu **bkt)
{
lock_map_release(&tbl->dep_map);
bit_spin_unlock(0, (unsigned long *)bkt);
@@ -365,48 +364,41 @@ static inline struct rhash_head *__rht_p
* access is guaranteed, such as when destroying the table.
*/
static inline struct rhash_head *rht_ptr_rcu(
- struct rhash_lock_head *const *p)
+ struct rhash_lock_head __rcu *const *bkt)
{
- struct rhash_lock_head __rcu *const *bkt = (void *)p;
return __rht_ptr(rcu_dereference(*bkt), bkt);
}

static inline struct rhash_head *rht_ptr(
- struct rhash_lock_head *const *p,
+ struct rhash_lock_head __rcu *const *bkt,
struct bucket_table *tbl,
unsigned int hash)
{
- struct rhash_lock_head __rcu *const *bkt = (void *)p;
return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt);
}

static inline struct rhash_head *rht_ptr_exclusive(
- struct rhash_lock_head *const *p)
+ struct rhash_lock_head __rcu *const *bkt)
{
- struct rhash_lock_head __rcu *const *bkt = (void *)p;
return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt);
}

-static inline void rht_assign_locked(struct rhash_lock_head **bkt,
+static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
struct rhash_head *obj)
{
- struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
-
if (rht_is_a_nulls(obj))
obj = NULL;
- rcu_assign_pointer(*p, (void *)((unsigned long)obj | BIT(0)));
+ rcu_assign_pointer(*bkt, (void *)((unsigned long)obj | BIT(0)));
}

static inline void rht_assign_unlock(struct bucket_table *tbl,
- struct rhash_lock_head **bkt,
+ struct rhash_lock_head __rcu **bkt,
struct rhash_head *obj)
{
- struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
-
if (rht_is_a_nulls(obj))
obj = NULL;
lock_map_release(&tbl->dep_map);
- rcu_assign_pointer(*p, obj);
+ rcu_assign_pointer(*bkt, (void *)obj);
preempt_enable();
__release(bitlock);
local_bh_enable();
@@ -594,7 +586,7 @@ static inline struct rhash_head *__rhash
.ht = ht,
.key = key,
};
- struct rhash_lock_head *const *bkt;
+ struct rhash_lock_head __rcu *const *bkt;
struct bucket_table *tbl;
struct rhash_head *he;
unsigned int hash;
@@ -710,7 +702,7 @@ static inline void *__rhashtable_insert_
.ht = ht,
.key = key,
};
- struct rhash_lock_head **bkt;
+ struct rhash_lock_head __rcu **bkt;
struct rhash_head __rcu **pprev;
struct bucket_table *tbl;
struct rhash_head *head;
@@ -996,7 +988,7 @@ static inline int __rhashtable_remove_fa
struct rhash_head *obj, const struct rhashtable_params params,
bool rhlist)
{
- struct rhash_lock_head **bkt;
+ struct rhash_lock_head __rcu **bkt;
struct rhash_head __rcu **pprev;
struct rhash_head *he;
unsigned int hash;
@@ -1148,7 +1140,7 @@ static inline int __rhashtable_replace_f
struct rhash_head *obj_old, struct rhash_head *obj_new,
const struct rhashtable_params params)
{
- struct rhash_lock_head **bkt;
+ struct rhash_lock_head __rcu **bkt;
struct rhash_head __rcu **pprev;
struct rhash_head *he;
unsigned int hash;
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -31,7 +31,7 @@

union nested_table {
union nested_table __rcu *table;
- struct rhash_lock_head *bucket;
+ struct rhash_lock_head __rcu *bucket;
};

static u32 head_hashfn(struct rhashtable *ht,
@@ -213,7 +213,7 @@ static struct bucket_table *rhashtable_l
}

static int rhashtable_rehash_one(struct rhashtable *ht,
- struct rhash_lock_head **bkt,
+ struct rhash_lock_head __rcu **bkt,
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
@@ -266,7 +266,7 @@ static int rhashtable_rehash_chain(struc
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
- struct rhash_lock_head **bkt = rht_bucket_var(old_tbl, old_hash);
+ struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash);
int err;

if (!bkt)
@@ -476,7 +476,7 @@ fail:
}

static void *rhashtable_lookup_one(struct rhashtable *ht,
- struct rhash_lock_head **bkt,
+ struct rhash_lock_head __rcu **bkt,
struct bucket_table *tbl, unsigned int hash,
const void *key, struct rhash_head *obj)
{
@@ -526,12 +526,10 @@ static void *rhashtable_lookup_one(struc
return ERR_PTR(-ENOENT);
}

-static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,
- struct rhash_lock_head **bkt,
- struct bucket_table *tbl,
- unsigned int hash,
- struct rhash_head *obj,
- void *data)
+static struct bucket_table *rhashtable_insert_one(
+ struct rhashtable *ht, struct rhash_lock_head __rcu **bkt,
+ struct bucket_table *tbl, unsigned int hash, struct rhash_head *obj,
+ void *data)
{
struct bucket_table *new_tbl;
struct rhash_head *head;
@@ -582,7 +580,7 @@ static void *rhashtable_try_insert(struc
{
struct bucket_table *new_tbl;
struct bucket_table *tbl;
- struct rhash_lock_head **bkt;
+ struct rhash_lock_head __rcu **bkt;
unsigned int hash;
void *data;

@@ -1164,8 +1162,8 @@ void rhashtable_destroy(struct rhashtabl
}
EXPORT_SYMBOL_GPL(rhashtable_destroy);

-struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl,
- unsigned int hash)
+struct rhash_lock_head __rcu **__rht_bucket_nested(
+ const struct bucket_table *tbl, unsigned int hash)
{
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
unsigned int index = hash & ((1 << tbl->nest) - 1);
@@ -1193,10 +1191,10 @@ struct rhash_lock_head **__rht_bucket_ne
}
EXPORT_SYMBOL_GPL(__rht_bucket_nested);

-struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl,
- unsigned int hash)
+struct rhash_lock_head __rcu **rht_bucket_nested(
+ const struct bucket_table *tbl, unsigned int hash)
{
- static struct rhash_lock_head *rhnull;
+ static struct rhash_lock_head __rcu *rhnull;

if (!rhnull)
INIT_RHT_NULLS_HEAD(rhnull);
@@ -1204,9 +1202,8 @@ struct rhash_lock_head **rht_bucket_nest
}
EXPORT_SYMBOL_GPL(rht_bucket_nested);

-struct rhash_lock_head **rht_bucket_nested_insert(struct rhashtable *ht,
- struct bucket_table *tbl,
- unsigned int hash)
+struct rhash_lock_head __rcu **rht_bucket_nested_insert(
+ struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
{
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
unsigned int index = hash & ((1 << tbl->nest) - 1);