From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B880CC7EE37 for ; Thu, 8 Jun 2023 14:24:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=E1OFXV0IS4fzFv7uKo7k3RBG9f5WRT17rw5GTnP1GD8=; b=QE9KVONmKd6opT CD/zbIm0oowTfKD8VyarKE1SNvdAaXnNfbG1Bg5o7L/Z7NWeNMd1S9seO19TrNYYn33r5f2BxXsz9 s6HOdPJPMpJ1Rhxk70G3lCmKXd9P9hp0SWOHHevsdMMaU4+dT00KzXkNHW597mn5UvqFFm3favEPK TqUYf6+g90UkH9CU9xE8DDWnnnaDHsC6OKIn03BwCnhxRaW+ltVmGKxgPtHx4uJajokQ4iiBmB8hN vbAX88/tc9Zs6Bh0QDO+F7o7UcDmRTOs3zhmSAln3UU/kj16PyajY/2e75lC2ZHn7uEkoZ57Xh3nH 9sxb1Vux+H7O93NXMcWQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q7GZI-009cFQ-1L; Thu, 08 Jun 2023 14:24:52 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q7GZF-009cDN-1m for linux-um@lists.infradead.org; Thu, 08 Jun 2023 14:24:50 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 24B2164E21; Thu, 8 Jun 2023 14:24:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52D36C4339E; Thu, 8 Jun 2023 14:24:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686234288; bh=Ap3GuMqINZf2WdIT1xsNL1OzEvsLgkbr6RhrjaSFN2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E/ppkNpUa1T5/FB+OZN82dq2UDzQIyU5Cbo8U3TTO4UUNzBPXl51gEj6FYXPHd0C0 B8fBUUD/WnNo6CND5zxE7A91YlNR8D75vEQqCmvaXDREUZMvckx6QEyeAr2D8LRUg6 mTEF3tCzZrWR/Bz+RWDK09Bl8RxWyDtiAseu46h6FEXk+pM2XpyEbH01OEkUhVaYt3 N6AWER4bq6Z6hZwWxZc4TOIfkzhSS9PaCantt/xrBbkDTIhgc/96+WPERBmKn2RSCz ItV8rK4Zh871ZfPPMNhWASgocY09hJn0uporPngp75NKd2+x//eEWrcaAry+aGCdFy ehyl0GtZu4Lag== From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Nathan Chancellor , Nick Desaulniers , Nicolas Schier , linux-um@lists.infradead.org, Masahiro Yamada Subject: [PATCH v7 07/11] modpost: use null string instead of NULL pointer for default namespace Date: Thu, 8 Jun 2023 23:24:24 +0900 Message-Id: <20230608142428.256985-8-masahiroy@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230608142428.256985-1-masahiroy@kernel.org> References: <20230608142428.256985-1-masahiroy@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230608_072449_672761_0880F9AB X-CRM114-Status: GOOD ( 15.10 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org The default namespace is the null string, "". When set, the null string "" is converted to NULL: s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL; When printed, the NULL pointer is get back to the null string: sym->namespace ?: "" This saves 1 byte memory allocated for "", but loses the readability. In kernel-space, we strive to save memory, but modpost is a userspace tool used to build the kernel. On modern systems, such small piece of memory is not a big deal. Handle the namespace string as is. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/modpost.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 4b0a009de0fb..7044b257424a 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -300,6 +300,13 @@ static bool contains_namespace(struct list_head *head, const char *namespace) { struct namespace_list *list; + /* + * The default namespace is null string "", which is always implicitly + * contained. + */ + if (!namespace[0]) + return true; + list_for_each_entry(list, head, list) { if (!strcmp(list->namespace, namespace)) return true; @@ -369,7 +376,7 @@ static struct symbol *sym_add_exported(const char *name, struct module *mod, s = alloc_symbol(name); s->module = mod; s->is_gpl_only = gpl_only; - s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL; + s->namespace = NOFAIL(strdup(namespace)); list_add_tail(&s->list, &mod->exported_symbols); hash_add_symbol(s); @@ -1823,8 +1830,7 @@ static void check_exports(struct module *mod) else basename = mod->name; - if (exp->namespace && - !contains_namespace(&mod->imported_namespaces, exp->namespace)) { + if (!contains_namespace(&mod->imported_namespaces, exp->namespace)) { modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR, "module %s uses symbol %s from namespace %s, but does not import it.\n", basename, exp->name, exp->namespace); @@ -1910,8 +1916,7 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod) list_for_each_entry(sym, &mod->exported_symbols, list) buf_printf(buf, "KSYMTAB_%s(%s, \"%s\", \"%s\");\n", sym->is_func ? "FUNC" : "DATA", sym->name, - sym->is_gpl_only ? "_gpl" : "", - sym->namespace ?: ""); + sym->is_gpl_only ? "_gpl" : "", sym->namespace); if (!modversions) return; @@ -2179,7 +2184,7 @@ static void write_dump(const char *fname) buf_printf(&buf, "0x%08x\t%s\t%s\tEXPORT_SYMBOL%s\t%s\n", sym->crc, sym->name, mod->name, sym->is_gpl_only ? "_GPL" : "", - sym->namespace ?: ""); + sym->namespace); } } write_buf(&buf, fname); -- 2.39.2 _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um