Commit 7d9c71e1 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: Extract generic string hashing function for reuse 



Calculating a hash of zero-terminated string is a common need when using
hashmap, so extract it for reuse.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200926011357.2366158-5-andriin@fb.com
parent 192f5a1f

tools/lib/bpf/btf_dump.c

+1 −8
Original line number Diff line number Diff line
@@ -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)

tools/lib/bpf/hashmap.h

+12 −0
Original line number Diff line number Diff line
@@ -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);