diff options
| -rw-r--r-- | include/linux/rhashtable.h | 34 | ||||
| -rw-r--r-- | lib/rhashtable.c | 8 |
2 files changed, 31 insertions, 11 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index eb7111039247..20f9c6af7473 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -75,8 +75,19 @@ struct bucket_table { struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp; }; +/* + * NULLS_MARKER() expects a hash value with the low + * bits mostly likely to be significant, and it discards + * the msb. + * We git it an address, in which the bottom 2 bits are + * always 0, and the msb might be significant. + * So we shift the address down one bit to align with + * expectations and avoid losing a significant bit. + */ +#define RHT_NULLS_MARKER(ptr) \ + ((void *)NULLS_MARKER(((unsigned long) (ptr)) >> 1)) #define INIT_RHT_NULLS_HEAD(ptr) \ - ((ptr) = (typeof(ptr)) NULLS_MARKER(0)) + ((ptr) = RHT_NULLS_MARKER(&(ptr))) static inline bool rht_is_a_nulls(const struct rhash_head *ptr) { @@ -471,6 +482,7 @@ static inline struct rhash_head *__rhashtable_lookup( .ht = ht, .key = key, }; + struct rhash_head __rcu * const *head; struct bucket_table *tbl; struct rhash_head *he; unsigned int hash; @@ -478,13 +490,19 @@ static inline struct rhash_head *__rhashtable_lookup( tbl = rht_dereference_rcu(ht->tbl, ht); restart: hash = rht_key_hashfn(ht, tbl, key, params); - rht_for_each_rcu(he, tbl, hash) { - if (params.obj_cmpfn ? - params.obj_cmpfn(&arg, rht_obj(ht, he)) : - rhashtable_compare(&arg, rht_obj(ht, he))) - continue; - return he; - } + head = rht_bucket(tbl, hash); + do { + rht_for_each_rcu_continue(he, *head, tbl, hash) { + if (params.obj_cmpfn ? + params.obj_cmpfn(&arg, rht_obj(ht, he)) : + rhashtable_compare(&arg, rht_obj(ht, he))) + continue; + return he; + } + /* An object might have been moved to a different hash chain, + * while we walk along it - better check and retry. + */ + } while (he != RHT_NULLS_MARKER(head)); /* Ensure we see any new tables. */ smp_rmb(); diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 30526afa8343..852ffa5160f1 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -1179,8 +1179,7 @@ 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 = - (struct rhash_head __rcu *)NULLS_MARKER(0); + 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; @@ -1198,8 +1197,11 @@ struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, subhash >>= shift; } - if (!ntbl) + if (!ntbl) { + if (!rhnull) + INIT_RHT_NULLS_HEAD(rhnull); return &rhnull; + } return &ntbl[subhash].bucket; |