Messages in this thread Patch in this message | | | From | NeilBrown <> | Date | Fri, 06 Jul 2018 17:22:30 +1000 | Subject | [PATCH 3/5] rhashtable: allow rht_bucket_var to return NULL. |
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Rather than returning a pointer 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.
Signed-off-by: NeilBrown <neilb@suse.com> --- 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 26ed3b299028..a4ff6ae524a0 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -284,6 +284,8 @@ 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); @@ -313,7 +315,7 @@ 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]; } @@ -916,6 +918,8 @@ static inline int __rhashtable_remove_fast_one( spin_lock_bh(lock); pprev = rht_bucket_var(tbl, hash); + if (!pprev) + goto out; rht_for_each_continue(he, *pprev, tbl, hash) { struct rhlist_head *list; @@ -960,6 +964,7 @@ static inline int __rhashtable_remove_fast_one( break; } +out: spin_unlock_bh(lock); if (err > 0) { @@ -1068,6 +1073,8 @@ static inline int __rhashtable_replace_fast( spin_lock_bh(lock); pprev = rht_bucket_var(tbl, hash); + if (!pprev) + goto out; rht_for_each_continue(he, *pprev, tbl, hash) { if (he != obj_old) { pprev = &he->next; @@ -1079,7 +1086,7 @@ 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 27a5ffa993d4..7a68c1f0b6d0 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -240,8 +240,10 @@ 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_continue(entry, *pprev, old_tbl, old_hash) { err = 0; next = rht_dereference_bucket(entry->next, old_tbl, old_hash); @@ -498,6 +500,8 @@ 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_continue(head, *pprev, tbl, hash) { struct rhlist_head *list; struct rhlist_head *plist; @@ -1160,11 +1164,10 @@ 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; @@ -1182,15 +1185,23 @@ struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, subhash >>= shift; } - if (!ntbl) { - if (!rhnull) - INIT_RHT_NULLS_HEAD(rhnull, NULL, 0); - 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,
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