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=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9DBA6C282C0 for ; Thu, 24 Jan 2019 02:28:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D6AD2184C for ; Thu, 24 Jan 2019 02:28:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548296907; bh=/9oaBKKDAPyKylbGIZAFDm/ELv3Sw3tVomFs+zkbxSM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=FQepO9PXydBlSdcX0yookfpOUJAQBkXAFP9jPav4lAI8h/f8Xo8vMUhL+tFKsQ0CY WfmIt2XzbZiFHBchWGLzgxLssJ1Kr6G/XkcxyU0V82NvCan3VEz3rsgpV4/45zcIYa oyPvb7l8gr4edCI+bs5MTPj2mwMsYbK0LA43efn4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727058AbfAXC1A (ORCPT ); Wed, 23 Jan 2019 21:27:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:59902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726249AbfAXC07 (ORCPT ); Wed, 23 Jan 2019 21:26:59 -0500 Received: from devbox (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5315821872; Thu, 24 Jan 2019 02:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548296818; bh=/9oaBKKDAPyKylbGIZAFDm/ELv3Sw3tVomFs+zkbxSM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=yBTH2Zq1VvknLjwn2rYh5qd4xL3HNY+7sxmHOl0QiK9fWvptgcCknGfA89bXKN5Vj OZgPoOEXeyz8aAjaIBJ0ua5ZK+XZkVEDvj01NvsEJgov9wMk5aZ7iIsrhTEGqQtpey +7nTPz+pxY4qbk9yB7uS6i7/wf2gYxUTzc8JO/yw= Date: Thu, 24 Jan 2019 11:26:52 +0900 From: Masami Hiramatsu To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Masami Hiramatsu , Ulf Hansson , Gary R Hook , Heiko Carstens Subject: Re: [PATCH 2/2] debugfs: return error values, not NULL Message-Id: <20190124112652.f31fc4b8dd9892f0d2f84790@kernel.org> In-Reply-To: <20190123102814.GB17123@kroah.com> References: <20190123102702.GA17123@kroah.com> <20190123102814.GB17123@kroah.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 23 Jan 2019 11:28:14 +0100 Greg Kroah-Hartman wrote: > When an error happens, debugfs should return an error pointer value, not > NULL. This will prevent the totally theoretical error where a debugfs > call fails due to lack of memory, returning NULL, and that dentry value > is then passed to another debugfs call, which would end up succeeding, > creating a file at the root of the debugfs tree, but would then be > impossible to remove (because you can not remove the directory NULL). > > So, to make everyone happy, always return errors, this makes the users > of debugfs much simpler (they do not have to ever check the return > value), and everyone can rest easy. With Greg's return check removal patches, I'm OK for this change. Reviewed-by: Masami Hiramatsu Thank you, > > Reported-by: Masami Hiramatsu > Reported-by: Ulf Hansson > Reported-by: Gary R Hook > Reported-by: Heiko Carstens > Cc: stable > Signed-off-by: Greg Kroah-Hartman > --- > fs/debugfs/inode.c | 39 ++++++++++++++++++++++----------------- > 1 file changed, 22 insertions(+), 17 deletions(-) > > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c > index 41ef452c1fcf..b16f8035b1af 100644 > --- a/fs/debugfs/inode.c > +++ b/fs/debugfs/inode.c > @@ -254,8 +254,8 @@ MODULE_ALIAS_FS("debugfs"); > * @parent: a pointer to the parent dentry of the file. > * > * This function will return a pointer to a dentry if it succeeds. If the file > - * doesn't exist or an error occurs, %NULL will be returned. The returned > - * dentry must be passed to dput() when it is no longer needed. > + * doesn't exist or an error occurs, %ERR_PTR(-ERROR) will be returned. The > + * returned dentry must be passed to dput() when it is no longer needed. > * > * If debugfs is not enabled in the kernel, the value -%ENODEV will be > * returned. > @@ -265,17 +265,17 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent) > struct dentry *dentry; > > if (IS_ERR(parent)) > - return NULL; > + return parent; > > if (!parent) > parent = debugfs_mount->mnt_root; > > dentry = lookup_one_len_unlocked(name, parent, strlen(name)); > if (IS_ERR(dentry)) > - return NULL; > + return dentry; > if (!d_really_is_positive(dentry)) { > dput(dentry); > - return NULL; > + return ERR_PTR(-EINVAL); > } > return dentry; > } > @@ -324,7 +324,7 @@ static struct dentry *failed_creating(struct dentry *dentry) > inode_unlock(d_inode(dentry->d_parent)); > dput(dentry); > simple_release_fs(&debugfs_mount, &debugfs_mount_count); > - return NULL; > + return ERR_PTR(-ENOMEM); > } > > static struct dentry *end_creating(struct dentry *dentry) > @@ -347,7 +347,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, > dentry = start_creating(name, parent); > > if (IS_ERR(dentry)) > - return NULL; > + return dentry; > > inode = debugfs_get_inode(dentry->d_sb); > if (unlikely(!inode)) > @@ -386,7 +386,8 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, > * This function will return a pointer to a dentry if it succeeds. This > * pointer must be passed to the debugfs_remove() function when the file is > * to be removed (no automatic cleanup happens if your module is unloaded, > - * you are responsible here.) If an error occurs, %NULL will be returned. > + * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be > + * returned. > * > * If debugfs is not enabled in the kernel, the value -%ENODEV will be > * returned. > @@ -464,7 +465,8 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); > * This function will return a pointer to a dentry if it succeeds. This > * pointer must be passed to the debugfs_remove() function when the file is > * to be removed (no automatic cleanup happens if your module is unloaded, > - * you are responsible here.) If an error occurs, %NULL will be returned. > + * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be > + * returned. > * > * If debugfs is not enabled in the kernel, the value -%ENODEV will be > * returned. > @@ -495,7 +497,8 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_size); > * This function will return a pointer to a dentry if it succeeds. This > * pointer must be passed to the debugfs_remove() function when the file is > * to be removed (no automatic cleanup happens if your module is unloaded, > - * you are responsible here.) If an error occurs, %NULL will be returned. > + * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be > + * returned. > * > * If debugfs is not enabled in the kernel, the value -%ENODEV will be > * returned. > @@ -506,7 +509,7 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) > struct inode *inode; > > if (IS_ERR(dentry)) > - return NULL; > + return dentry; > > inode = debugfs_get_inode(dentry->d_sb); > if (unlikely(!inode)) > @@ -545,7 +548,7 @@ struct dentry *debugfs_create_automount(const char *name, > struct inode *inode; > > if (IS_ERR(dentry)) > - return NULL; > + return dentry; > > inode = debugfs_get_inode(dentry->d_sb); > if (unlikely(!inode)) > @@ -581,8 +584,8 @@ EXPORT_SYMBOL(debugfs_create_automount); > * This function will return a pointer to a dentry if it succeeds. This > * pointer must be passed to the debugfs_remove() function when the symbolic > * link is to be removed (no automatic cleanup happens if your module is > - * unloaded, you are responsible here.) If an error occurs, %NULL will be > - * returned. > + * unloaded, you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) > + * will be returned. > * > * If debugfs is not enabled in the kernel, the value -%ENODEV will be > * returned. > @@ -594,12 +597,12 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, > struct inode *inode; > char *link = kstrdup(target, GFP_KERNEL); > if (!link) > - return NULL; > + return ERR_PTR(-ENOMEM); > > dentry = start_creating(name, parent); > if (IS_ERR(dentry)) { > kfree(link); > - return NULL; > + return dentry; > } > > inode = debugfs_get_inode(dentry->d_sb); > @@ -827,7 +830,9 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, > if (dentry && !IS_ERR(dentry)) > dput(dentry); > unlock_rename(new_dir, old_dir); > - return NULL; > + if (IS_ERR(dentry)) > + return dentry; > + return ERR_PTR(-EINVAL); > } > EXPORT_SYMBOL_GPL(debugfs_rename); > > -- > 2.20.1 > -- Masami Hiramatsu