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Message-Id: <E1hRAg6-0004Fn-QR@gondobar>
Date: Thu, 16 May 2019 15:19:46 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Jakub Kicinski <jakub.kicinski@...ronome.com>, davem@...emloft.net,
tgraf@...g.ch, netdev@...r.kernel.org, oss-drivers@...ronome.com,
neilb@...e.com, Simon Horman <simon.horman@...ronome.com>
Subject: [PATCH 1/2] rhashtable: Remove RCU marking from rhash_lock_head
The opaque type rhash_lock_head should not be marked with __rcu
because it can never be dereferenced. We should apply the RCU
marking when we turn it into a pointer which can be dereferenced.
This patch does exactly that. This fixes a number of sparse
warnings as well as getting rid of some unnecessary RCU checking.
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
---
include/linux/rhashtable.h | 58 ++++++++++++++++++++++++---------------------
lib/rhashtable.c | 28 ++++++++++-----------
2 files changed, 46 insertions(+), 40 deletions(-)
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index f7714d3b46bd..9f8bc06d4136 100644
--- 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 __rcu *buckets[] ____cacheline_aligned_in_smp;
+ struct rhash_lock_head *buckets[] ____cacheline_aligned_in_smp;
};
/*
@@ -261,13 +261,13 @@ void rhashtable_free_and_destroy(struct rhashtable *ht,
void *arg);
void rhashtable_destroy(struct rhashtable *ht);
-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);
+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);
#define rht_dereference(p, ht) \
rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
@@ -284,21 +284,21 @@ struct rhash_lock_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
#define rht_entry(tpos, pos, member) \
({ tpos = container_of(pos, typeof(*tpos), member); 1; })
-static inline struct rhash_lock_head __rcu *const *rht_bucket(
+static inline struct rhash_lock_head *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 __rcu **rht_bucket_var(
+static inline struct rhash_lock_head **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 __rcu **rht_bucket_insert(
+static inline struct rhash_lock_head **rht_bucket_insert(
struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
@@ -349,6 +349,12 @@ static inline void rht_unlock(struct bucket_table *tbl,
local_bh_enable();
}
+static inline struct rhash_head __rcu *__rht_ptr(
+ struct rhash_lock_head *const *bkt)
+{
+ return (struct rhash_head __rcu *)((unsigned long)*bkt & ~BIT(0));
+}
+
/*
* Where 'bkt' is a bucket and might be locked:
* rht_ptr() dereferences that pointer and clears the lock bit.
@@ -356,30 +362,30 @@ static inline void rht_unlock(struct bucket_table *tbl,
* access is guaranteed, such as when destroying the table.
*/
static inline struct rhash_head *rht_ptr(
- struct rhash_lock_head __rcu * const *bkt,
+ struct rhash_lock_head *const *bkt,
struct bucket_table *tbl,
unsigned int hash)
{
- const struct rhash_lock_head *p =
- rht_dereference_bucket_rcu(*bkt, tbl, hash);
+ struct rhash_head __rcu *p = __rht_ptr(bkt);
- if ((((unsigned long)p) & ~BIT(0)) == 0)
+ if (!p)
return RHT_NULLS_MARKER(bkt);
- return (void *)(((unsigned long)p) & ~BIT(0));
+
+ return rht_dereference_bucket_rcu(p, tbl, hash);
}
static inline struct rhash_head *rht_ptr_exclusive(
- struct rhash_lock_head __rcu * const *bkt)
+ struct rhash_lock_head *const *bkt)
{
- const struct rhash_lock_head *p =
- rcu_dereference_protected(*bkt, 1);
+ struct rhash_head __rcu *p = __rht_ptr(bkt);
if (!p)
return RHT_NULLS_MARKER(bkt);
- return (void *)(((unsigned long)p) & ~BIT(0));
+
+ return rcu_dereference_protected(p, 1);
}
-static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
+static inline void rht_assign_locked(struct rhash_lock_head **bkt,
struct rhash_head *obj)
{
struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
@@ -390,7 +396,7 @@ static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
}
static inline void rht_assign_unlock(struct bucket_table *tbl,
- struct rhash_lock_head __rcu **bkt,
+ struct rhash_lock_head **bkt,
struct rhash_head *obj)
{
struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
@@ -587,7 +593,7 @@ static inline struct rhash_head *__rhashtable_lookup(
.ht = ht,
.key = key,
};
- struct rhash_lock_head __rcu * const *bkt;
+ struct rhash_lock_head *const *bkt;
struct bucket_table *tbl;
struct rhash_head *he;
unsigned int hash;
@@ -703,7 +709,7 @@ static inline void *__rhashtable_insert_fast(
.ht = ht,
.key = key,
};
- struct rhash_lock_head __rcu **bkt;
+ struct rhash_lock_head **bkt;
struct rhash_head __rcu **pprev;
struct bucket_table *tbl;
struct rhash_head *head;
@@ -989,7 +995,7 @@ static inline int __rhashtable_remove_fast_one(
struct rhash_head *obj, const struct rhashtable_params params,
bool rhlist)
{
- struct rhash_lock_head __rcu **bkt;
+ struct rhash_lock_head **bkt;
struct rhash_head __rcu **pprev;
struct rhash_head *he;
unsigned int hash;
@@ -1141,7 +1147,7 @@ static inline int __rhashtable_replace_fast(
struct rhash_head *obj_old, struct rhash_head *obj_new,
const struct rhashtable_params params)
{
- struct rhash_lock_head __rcu **bkt;
+ struct rhash_lock_head **bkt;
struct rhash_head __rcu **pprev;
struct rhash_head *he;
unsigned int hash;
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 6529fe1b45c1..7708699a5b96 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -34,7 +34,7 @@
union nested_table {
union nested_table __rcu *table;
- struct rhash_lock_head __rcu *bucket;
+ struct rhash_lock_head *bucket;
};
static u32 head_hashfn(struct rhashtable *ht,
@@ -216,7 +216,7 @@ static struct bucket_table *rhashtable_last_table(struct rhashtable *ht,
}
static int rhashtable_rehash_one(struct rhashtable *ht,
- struct rhash_lock_head __rcu **bkt,
+ struct rhash_lock_head **bkt,
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
@@ -269,7 +269,7 @@ static int rhashtable_rehash_chain(struct rhashtable *ht,
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
- struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash);
+ struct rhash_lock_head **bkt = rht_bucket_var(old_tbl, old_hash);
int err;
if (!bkt)
@@ -478,7 +478,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
}
static void *rhashtable_lookup_one(struct rhashtable *ht,
- struct rhash_lock_head __rcu **bkt,
+ struct rhash_lock_head **bkt,
struct bucket_table *tbl, unsigned int hash,
const void *key, struct rhash_head *obj)
{
@@ -529,7 +529,7 @@ static void *rhashtable_lookup_one(struct rhashtable *ht,
}
static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,
- struct rhash_lock_head __rcu **bkt,
+ struct rhash_lock_head **bkt,
struct bucket_table *tbl,
unsigned int hash,
struct rhash_head *obj,
@@ -584,7 +584,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
{
struct bucket_table *new_tbl;
struct bucket_table *tbl;
- struct rhash_lock_head __rcu **bkt;
+ struct rhash_lock_head **bkt;
unsigned int hash;
void *data;
@@ -1166,8 +1166,8 @@ void rhashtable_destroy(struct rhashtable *ht)
}
EXPORT_SYMBOL_GPL(rhashtable_destroy);
-struct rhash_lock_head __rcu **__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)
{
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
unsigned int index = hash & ((1 << tbl->nest) - 1);
@@ -1195,10 +1195,10 @@ struct rhash_lock_head __rcu **__rht_bucket_nested(const struct bucket_table *tb
}
EXPORT_SYMBOL_GPL(__rht_bucket_nested);
-struct rhash_lock_head __rcu **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)
{
- static struct rhash_lock_head __rcu *rhnull;
+ static struct rhash_lock_head *rhnull;
if (!rhnull)
INIT_RHT_NULLS_HEAD(rhnull);
@@ -1206,9 +1206,9 @@ struct rhash_lock_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
}
EXPORT_SYMBOL_GPL(rht_bucket_nested);
-struct rhash_lock_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
- 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)
{
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
unsigned int index = hash & ((1 << tbl->nest) - 1);
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