From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED678C04AB4 for ; Thu, 16 May 2019 07:19:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4AD52087B for ; Thu, 16 May 2019 07:19:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726653AbfEPHTy (ORCPT ); Thu, 16 May 2019 03:19:54 -0400 Received: from orcrist.hmeau.com ([5.180.42.13]:44066 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726277AbfEPHTy (ORCPT ); Thu, 16 May 2019 03:19:54 -0400 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtps (Exim 4.89 #2 (Debian)) id 1hRAg7-0004PR-4t; Thu, 16 May 2019 15:19:47 +0800 Received: from herbert by gondobar with local (Exim 4.89) (envelope-from ) id 1hRAg6-0004Fn-QR; Thu, 16 May 2019 15:19:46 +0800 Subject: [PATCH 1/2] rhashtable: Remove RCU marking from rhash_lock_head References: <20190516051622.b4x6hlkuevof4jzr@gondor.apana.org.au> To: Jakub Kicinski , davem@davemloft.net, tgraf@suug.ch, netdev@vger.kernel.org, oss-drivers@netronome.com, neilb@suse.com, Simon Horman Message-Id: From: Herbert Xu Date: Thu, 16 May 2019 15:19:46 +0800 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 --- 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);