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rhashtable: consolidate hash computation in rht_key_get_hash()

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The else-if and else branches in rht_key_get_hash() both compute a hash
using either params.hashfn or jhash, differing only in the source of
key_len (params.key_len vs ht->p.key_len). Merge the two branches into
one by using the ternary `params.key_len ?: ht->p.key_len` to select
the key length, removing the duplicated logic.

This also improves the performance of the else branch which previously
always used jhash and never fell through to jhash2. This branch is going
to be used by BPF resizable hashmap, which wraps rhashtable:
https://lore.kernel.org/bpf/20260205-rhash-v1-0-30dd6d63c462@meta.com/

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Mykyta Yatsenko
2026-02-24 19:29:54 +00:00
committed by Herbert Xu
parent 68e96c9736
commit c9429bf564
1 changed files with 3 additions and 10 deletions
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13
include/linux/rhashtable.h
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@@ -129,10 +129,10 @@ static __always_inline unsigned int rht_key_get_hash(struct rhashtable *ht,
unsigned int hash;
/* params must be equal to ht->p if it isn't constant. */
if (!__builtin_constant_p(params.key_len))
if (!__builtin_constant_p(params.key_len)) {
hash = ht->p.hashfn(key, ht->key_len, hash_rnd);
else if (params.key_len) {
unsigned int key_len = params.key_len;
} else {
unsigned int key_len = params.key_len ? : ht->p.key_len;
if (params.hashfn)
hash = params.hashfn(key, key_len, hash_rnd);
@@ -140,13 +140,6 @@ static __always_inline unsigned int rht_key_get_hash(struct rhashtable *ht,
hash = jhash(key, key_len, hash_rnd);
else
hash = jhash2(key, key_len / sizeof(u32), hash_rnd);
} else {
unsigned int key_len = ht->p.key_len;
if (params.hashfn)
hash = params.hashfn(key, key_len, hash_rnd);
else
hash = jhash(key, key_len, hash_rnd);
}
return hash;