From ff302db965b57c141297911ea647d36d11fedfbe Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 2 Apr 2019 10:07:45 +1100 Subject: [PATCH] rhashtable: allow rht_bucket_var to return NULL. Rather than returning a pointer to a static nulls, rht_bucket_var() now returns NULL if the bucket doesn't exist. This will make the next patch, which stores a bitlock in the bucket pointer, somewhat cleaner. This change involves introducing __rht_bucket_nested() which is like rht_bucket_nested(), but doesn't provide the static nulls, and changing rht_bucket_nested() to call this and possible provide a static nulls - as is still needed for the non-var case. Signed-off-by: NeilBrown Signed-off-by: David S. Miller --- include/linux/rhashtable.h | 11 +++++++++-- lib/rhashtable.c | 29 ++++++++++++++++++++--------- 2 files changed, 29 insertions(+), 11 deletions(-) diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index 86dfa417848d..0c9175aeab8a 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -265,6 +265,8 @@ void rhashtable_destroy(struct rhashtable *ht); struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, unsigned int hash); +struct rhash_head __rcu **__rht_bucket_nested(const struct bucket_table *tbl, + unsigned int hash); struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash); @@ -294,7 +296,7 @@ static inline struct rhash_head __rcu *const *rht_bucket( static inline struct rhash_head __rcu **rht_bucket_var( struct bucket_table *tbl, unsigned int hash) { - return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) : + return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) : &tbl->buckets[hash]; } @@ -890,6 +892,8 @@ static inline int __rhashtable_remove_fast_one( spin_lock_bh(lock); pprev = rht_bucket_var(tbl, hash); + if (!pprev) + goto out; rht_for_each_from(he, *pprev, tbl, hash) { struct rhlist_head *list; @@ -934,6 +938,7 @@ static inline int __rhashtable_remove_fast_one( break; } +out: spin_unlock_bh(lock); if (err > 0) { @@ -1042,6 +1047,8 @@ static inline int __rhashtable_replace_fast( spin_lock_bh(lock); pprev = rht_bucket_var(tbl, hash); + if (!pprev) + goto out; rht_for_each_from(he, *pprev, tbl, hash) { if (he != obj_old) { pprev = &he->next; @@ -1053,7 +1060,7 @@ static inline int __rhashtable_replace_fast( err = 0; break; } - +out: spin_unlock_bh(lock); return err; diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 6c4f5c8e9baa..b28fdd560ea9 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -237,8 +237,10 @@ static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash) goto out; err = -ENOENT; + if (!pprev) + goto out; - rht_for_each(entry, old_tbl, old_hash) { + rht_for_each_from(entry, *pprev, old_tbl, old_hash) { err = 0; next = rht_dereference_bucket(entry->next, old_tbl, old_hash); @@ -496,6 +498,8 @@ static void *rhashtable_lookup_one(struct rhashtable *ht, elasticity = RHT_ELASTICITY; pprev = rht_bucket_var(tbl, hash); + if (!pprev) + return ERR_PTR(-ENOENT); rht_for_each_from(head, *pprev, tbl, hash) { struct rhlist_head *list; struct rhlist_head *plist; @@ -1161,11 +1165,10 @@ void rhashtable_destroy(struct rhashtable *ht) } EXPORT_SYMBOL_GPL(rhashtable_destroy); -struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, - unsigned int hash) +struct rhash_head __rcu **__rht_bucket_nested(const struct bucket_table *tbl, + unsigned int hash) { const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); - static struct rhash_head __rcu *rhnull; unsigned int index = hash & ((1 << tbl->nest) - 1); unsigned int size = tbl->size >> tbl->nest; unsigned int subhash = hash; @@ -1183,15 +1186,23 @@ struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, subhash >>= shift; } - if (!ntbl) { - if (!rhnull) - INIT_RHT_NULLS_HEAD(rhnull); - return &rhnull; - } + if (!ntbl) + return NULL; return &ntbl[subhash].bucket; } +EXPORT_SYMBOL_GPL(__rht_bucket_nested); + +struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, + unsigned int hash) +{ + static struct rhash_head __rcu *rhnull; + + if (!rhnull) + INIT_RHT_NULLS_HEAD(rhnull); + return __rht_bucket_nested(tbl, hash) ?: &rhnull; +} EXPORT_SYMBOL_GPL(rht_bucket_nested); struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht, -- 2.39.5