linux-kernel - [PATCH 4/6] fixdep: refactor hash table lookup

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Date:   Sat, 31 Dec 2022 15:42:01 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Miguel Ojeda <ojeda@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>
Subject: [PATCH 4/6] fixdep: refactor hash table lookup

Change the hash table code so it will be easier to add the second table.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 scripts/basic/fixdep.c | 47 ++++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index 37a40520686f..b20777b888d7 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -113,7 +113,7 @@ struct item {
 };
 
 #define HASHSZ 256
-static struct item *hashtab[HASHSZ];
+static struct item *config_hashtab[HASHSZ];
 
 static unsigned int strhash(const char *str, unsigned int sz)
 {
@@ -125,25 +125,11 @@ static unsigned int strhash(const char *str, unsigned int sz)
 	return hash;
 }
 
-/*
- * Lookup a value in the configuration string.
- */
-static int is_defined_config(const char *name, int len, unsigned int hash)
-{
-	struct item *aux;
-
-	for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
-		if (aux->hash == hash && aux->len == len &&
-		    memcmp(aux->name, name, len) == 0)
-			return 1;
-	}
-	return 0;
-}
-
 /*
  * Add a new value to the configuration string.
  */
-static void define_config(const char *name, int len, unsigned int hash)
+static void add_to_hashtable(const char *name, int len, unsigned int hash,
+			     struct item *hashtab[])
 {
 	struct item *aux = malloc(sizeof(*aux) + len);
 
@@ -158,17 +144,34 @@ static void define_config(const char *name, int len, unsigned int hash)
 	hashtab[hash % HASHSZ] = aux;
 }
 
+/*
+ * Lookup a string in the hash table. If found, just return true.
+ * If not, add it to the hashtable and return false.
+ */
+static bool in_hashtable(const char *name, int len, struct item *hashtab[])
+{
+	struct item *aux;
+	unsigned int hash = strhash(name, len);
+
+	for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
+		if (aux->hash == hash && aux->len == len &&
+		    memcmp(aux->name, name, len) == 0)
+			return true;
+	}
+
+	add_to_hashtable(name, len, hash, hashtab);
+
+	return false;
+}
+
 /*
  * Record the use of a CONFIG_* word.
  */
 static void use_config(const char *m, int slen)
 {
-	unsigned int hash = strhash(m, slen);
-
-	if (is_defined_config(m, slen, hash))
-	    return;
+	if (in_hashtable(m, slen, config_hashtab))
+		return;
 
-	define_config(m, slen, hash);
 	/* Print out a dependency path from a symbol name. */
 	printf("    $(wildcard include/config/%.*s) \\\n", slen, m);
 }
-- 
2.34.1