[PATCH 1/2] kconfig: remove unneeded buffer allocation in zconf_initscan()

Masahiro Yamada
2024-01-07T13:19:54Z

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>
---

scripts/kconfig/lexer.l | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/scripts/kconfig/lexer.l b/scripts/kconfig/lexer.l
index cc386e443683..d75423ec4eae 100644
--- 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)
--
2.40.1