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 X-Spam-Level: X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5A0CC433E0 for ; Thu, 25 Mar 2021 19:44:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCA4961A3E for ; Thu, 25 Mar 2021 19:44:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230314AbhCYTn6 (ORCPT ); Thu, 25 Mar 2021 15:43:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:56100 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229833AbhCYTnY (ORCPT ); Thu, 25 Mar 2021 15:43:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CD9D0619C9; Thu, 25 Mar 2021 19:43:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616701404; bh=1r+GeFGCMbDDIXeRYKJ4Hm8F51/bPaP4XF8mxybzx2A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JGP1DZMB24r/DF69LXH/qos9xWt+IB2JQD2/pxxusRzuFj7yp8XP9X6ZX11xq7UI3 SqgDqD5EeTOq9jkARGuGO2Y0JjS2eKLD1lvQ4i83zw0FkGZLqPEa3b/DEr7vJrFQWM rHRuNJnaf0MP6CSUnAClzOox/qpLeEiVup7Sm+LLExLdFtmcCn/BLnD9OtQ7Oo6VBs d7Fde1+FRBsdZGBPah8hBCy9p2ot8rPBJtccyc2DJhao2COhMdQJ//x2+YRTz5xxdN EXnfAdx8UBx9lXiF0DKxfcGOPjRXFd0HRnsj3Zr8bwt/TO151jqIYDrDv/W5Pcm7br j61kk91T6iVTA== Date: Thu, 25 Mar 2021 12:43:22 -0700 From: Eric Biggers To: Gabriel Krisman Bertazi Cc: Shreeya Patel , tytso@mit.edu, adilger.kernel@dilger.ca, jaegeuk@kernel.org, chao@kernel.org, drosen@google.com, yuchao0@huawei.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, kernel@collabora.com, andre.almeida@collabora.com Subject: Re: [PATCH v4 2/5] fs: Check if utf8 encoding is loaded before calling utf8_unload() Message-ID: References: <20210325000811.1379641-1-shreeya.patel@collabora.com> <20210325000811.1379641-3-shreeya.patel@collabora.com> <878s6bt4gx.fsf@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <878s6bt4gx.fsf@collabora.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Mar 25, 2021 at 03:31:42PM -0400, Gabriel Krisman Bertazi wrote: > Eric Biggers writes: > > > On Thu, Mar 25, 2021 at 05:38:08AM +0530, Shreeya Patel wrote: > >> utf8_unload is being called if CONFIG_UNICODE is enabled. > >> The ifdef block doesn't check if utf8 encoding has been loaded > >> or not before calling the utf8_unload() function. > >> This is not the expected behavior since it would sometimes lead > >> to unloading utf8 even before loading it. > >> Hence, add a condition which will check if sb->encoding is NOT NULL > >> before calling the utf8_unload(). > >> > >> Reviewed-by: Gabriel Krisman Bertazi > >> Signed-off-by: Shreeya Patel > >> --- > >> fs/ext4/super.c | 6 ++++-- > >> fs/f2fs/super.c | 9 ++++++--- > >> 2 files changed, 10 insertions(+), 5 deletions(-) > >> > >> diff --git a/fs/ext4/super.c b/fs/ext4/super.c > >> index ad34a37278cd..e438d14f9a87 100644 > >> --- a/fs/ext4/super.c > >> +++ b/fs/ext4/super.c > >> @@ -1259,7 +1259,8 @@ static void ext4_put_super(struct super_block *sb) > >> fs_put_dax(sbi->s_daxdev); > >> fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy); > >> #ifdef CONFIG_UNICODE > >> - utf8_unload(sb->s_encoding); > >> + if (sb->s_encoding) > >> + utf8_unload(sb->s_encoding); > >> #endif > >> kfree(sbi); > >> } > > > > > > What's the benefit of this change? utf8_unload is a no-op when passed a NULL > > pointer; why not keep it that way? > > For the record, it no longer is a no-op after patch 5 of this series. > Honestly, I prefer making it explicitly at the caller that we are not > entering the function, like the patch does, instead of returning from it > immediately. Makes it more readable, IMO. > I don't think making all the callers do the NULL check is more readable. It's conventional for free-like functions to accept NULL pointers. See for example every other function in the code snippet above -- fs_put_dax(), fscrypt_free_dummy_policy(), and kfree(). This seems more like an issue with patch 5; it shouldn't be dropping the NULL check from unicode_unload(). - Eric