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| author |   Herbert Xu <herbert@gondor.apana.org.au> | 2017-04-27 13:44:51 +0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-04-27 11:48:24 -0400 |
| commit | 6d684e54690caef45cf14051ddeb7c71beeb681b (patch) | |
| tree | 1544faf80a19bf2fa47d9f2a1e5f2f98dbb17545 /include/linux/rhashtable.h | |
| parent | tcp: tcp_rack_reo_timeout() must update tp->tcp_mstamp (diff) | |
| download | wireguard-linux-6d684e54690caef45cf14051ddeb7c71beeb681b.tar.xz wireguard-linux-6d684e54690caef45cf14051ddeb7c71beeb681b.zip | |
rhashtable: Cap total number of entries to 2^31
When max_size is not set or if it set to a sufficiently large
value, the nelems counter can overflow. This would cause havoc
with the automatic shrinking as it would then attempt to fit a
huge number of entries into a tiny hash table.
This patch fixes this by adding max_elems to struct rhashtable
to cap the number of elements. This is set to 2^31 as nelems is
not a precise count. This is sufficiently smaller than UINT_MAX
that it should be safe.
When max_size is set max_elems will be lowered to at most twice
max_size as is the status quo.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/rhashtable.h')
| -rw-r--r-- | include/linux/rhashtable.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index ae93b65d13d7..45f89369c4c8 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -155,6 +155,7 @@ struct rhashtable_params { * @nelems: Number of elements in table * @key_len: Key length for hashfn * @p: Configuration parameters + * @max_elems: Maximum number of elements in table * @rhlist: True if this is an rhltable * @run_work: Deferred worker to expand/shrink asynchronously * @mutex: Mutex to protect current/future table swapping @@ -165,6 +166,7 @@ struct rhashtable { atomic_t nelems; unsigned int key_len; struct rhashtable_params p; + unsigned int max_elems; bool rhlist; struct work_struct run_work; struct mutex mutex; @@ -327,8 +329,7 @@ static inline bool rht_grow_above_100(const struct rhashtable *ht, static inline bool rht_grow_above_max(const struct rhashtable *ht, const struct bucket_table *tbl) { - return ht->p.max_size && - (atomic_read(&ht->nelems) / 2u) >= ht->p.max_size; + return atomic_read(&ht->nelems) >= ht->max_elems; } /* The bucket lock is selected based on the hash and protects mutations |