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-rw-r--r--include/linux/rhashtable.h19
-rw-r--r--lib/rhashtable.c11
2 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index dbcbcc59aa92..843ceca9a21e 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -17,6 +17,7 @@
#ifndef _LINUX_RHASHTABLE_H
#define _LINUX_RHASHTABLE_H
+#include <linux/atomic.h>
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/jhash.h>
@@ -100,6 +101,7 @@ struct rhashtable;
* @key_len: Length of key
* @key_offset: Offset of key in struct to be hashed
* @head_offset: Offset of rhash_head in struct to be hashed
+ * @insecure_max_entries: Maximum number of entries (may be exceeded)
* @max_size: Maximum size while expanding
* @min_size: Minimum size while shrinking
* @nulls_base: Base value to generate nulls marker
@@ -115,6 +117,7 @@ struct rhashtable_params {
size_t key_len;
size_t key_offset;
size_t head_offset;
+ unsigned int insecure_max_entries;
unsigned int max_size;
unsigned int min_size;
u32 nulls_base;
@@ -286,6 +289,18 @@ static inline bool rht_grow_above_100(const struct rhashtable *ht,
(!ht->p.max_size || tbl->size < ht->p.max_size);
}
+/**
+ * rht_grow_above_max - returns true if table is above maximum
+ * @ht: hash table
+ * @tbl: current table
+ */
+static inline bool rht_grow_above_max(const struct rhashtable *ht,
+ const struct bucket_table *tbl)
+{
+ return ht->p.insecure_max_entries &&
+ atomic_read(&ht->nelems) >= ht->p.insecure_max_entries;
+}
+
/* The bucket lock is selected based on the hash and protects mutations
* on a group of hash buckets.
*
@@ -589,6 +604,10 @@ restart:
goto out;
}
+ err = -E2BIG;
+ if (unlikely(rht_grow_above_max(ht, tbl)))
+ goto out;
+
if (unlikely(rht_grow_above_100(ht, tbl))) {
slow_path:
spin_unlock_bh(lock);
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index b28df4019ade..4396434e4715 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -14,6 +14,7 @@
* published by the Free Software Foundation.
*/
+#include <linux/atomic.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/log2.h>
@@ -446,6 +447,10 @@ int rhashtable_insert_slow(struct rhashtable *ht, const void *key,
if (key && rhashtable_lookup_fast(ht, key, ht->p))
goto exit;
+ err = -E2BIG;
+ if (unlikely(rht_grow_above_max(ht, tbl)))
+ goto exit;
+
err = -EAGAIN;
if (rhashtable_check_elasticity(ht, tbl, hash) ||
rht_grow_above_100(ht, tbl))
@@ -738,6 +743,12 @@ int rhashtable_init(struct rhashtable *ht,
if (params->max_size)
ht->p.max_size = rounddown_pow_of_two(params->max_size);
+ if (params->insecure_max_entries)
+ ht->p.insecure_max_entries =
+ rounddown_pow_of_two(params->insecure_max_entries);
+ else
+ ht->p.insecure_max_entries = ht->p.max_size * 2;
+
ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE);
/* The maximum (not average) chain length grows with the