kconfig: remove unneeded buffer allocation in zconf_initscan()

In Kconfig, there is a stack to save the lexer state for each inclusion
level.

Currently, it operates as an empty stack, with the 'current_buf' always
pointing to an empty buffer. There is no need to preallocate the buffer.
Change it to a full stack.

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

diff --git a/scripts/kconfig/lexer.l b/scripts/kconfig/lexer.l
index cc386e44368346c2309d2f60aab3cad10a5cefb0..d75423ec4eae1684c26c283eeaba13aa338d820c 100644 (file)
--- a/scripts/kconfig/lexer.l
+++ b/scripts/kconfig/lexer.l
@@ -391,9 +391,6 @@ void zconf_initscan(const char *name)
                exit(1);
        }
 
-       current_buf = xmalloc(sizeof(*current_buf));
-       memset(current_buf, 0, sizeof(*current_buf));
-
        current_file = file_lookup(name);
        yylineno = 1;
 }
@@ -403,9 +400,10 @@ void zconf_nextfile(const char *name)
        struct file *iter;
        struct file *file = file_lookup(name);
        struct buffer *buf = xmalloc(sizeof(*buf));
-       memset(buf, 0, sizeof(*buf));
 
-       current_buf->state = YY_CURRENT_BUFFER;
+       buf->state = YY_CURRENT_BUFFER;
+       buf->parent = current_buf;
+       current_buf = buf;
        yyin = zconf_fopen(file->name);
        if (!yyin) {
                fprintf(stderr, "%s:%d: can't open file \"%s\"\n",
@@ -413,8 +411,6 @@ void zconf_nextfile(const char *name)
                exit(1);
        }
        yy_switch_to_buffer(yy_create_buffer(yyin, YY_BUF_SIZE));
-       buf->parent = current_buf;
-       current_buf = buf;
 
        current_file->lineno = yylineno;
        file->parent = current_file;
@@ -441,20 +437,21 @@ void zconf_nextfile(const char *name)
 
 static void zconf_endfile(void)
 {
-       struct buffer *parent;
+       struct buffer *tmp;
 
        current_file = current_file->parent;
        if (current_file)
                yylineno = current_file->lineno;
 
-       parent = current_buf->parent;
-       if (parent) {
-               fclose(yyin);
-               yy_delete_buffer(YY_CURRENT_BUFFER);
-               yy_switch_to_buffer(parent->state);
-       }
-       free(current_buf);
-       current_buf = parent;
+       if (!current_buf)
+               return;
+
+       fclose(yyin);
+       yy_delete_buffer(YY_CURRENT_BUFFER);
+       yy_switch_to_buffer(current_buf->state);
+       tmp = current_buf;
+       current_buf = current_buf->parent;
+       free(tmp);
 }
 
 int zconf_lineno(void)