[PATCH v2 bpf-next 4/9] libbpf: extract generic string hashing function for reuse
From: Andrii Nakryiko <hidden>
Date: 2020-09-26 01:15:21
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
Calculating a hash of zero-terminated string is a common need when using hashmap, so extract it for reuse. Acked-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Andrii Nakryiko <redacted> --- tools/lib/bpf/btf_dump.c | 9 +-------- tools/lib/bpf/hashmap.h | 12 ++++++++++++ 2 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 6c079b3c8679..91310e528a3a 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c@@ -90,14 +90,7 @@ struct btf_dump { static size_t str_hash_fn(const void *key, void *ctx) { - const char *s = key; - size_t h = 0; - - while (*s) { - h = h * 31 + *s; - s++; - } - return h; + return str_hash(key); } static bool str_equal_fn(const void *a, const void *b, void *ctx)
diff --git a/tools/lib/bpf/hashmap.h b/tools/lib/bpf/hashmap.h
index e0af36b0e5d8..d9b385fe808c 100644
--- a/tools/lib/bpf/hashmap.h
+++ b/tools/lib/bpf/hashmap.h@@ -25,6 +25,18 @@ static inline size_t hash_bits(size_t h, int bits) #endif } +/* generic C-string hashing function */ +static inline size_t str_hash(const char *s) +{ + size_t h = 0; + + while (*s) { + h = h * 31 + *s; + s++; + } + return h; +} + typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx); typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
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2.24.1