Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757503Ab2HYTnb (ORCPT ); Sat, 25 Aug 2012 15:43:31 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:61623 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754617Ab2HYTn3 (ORCPT ); Sat, 25 Aug 2012 15:43:29 -0400 Date: Sat, 25 Aug 2012 23:43:25 +0400 From: Cyrill Gorcunov To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alexey Dobriyan , Andrew Morton , Pavel Emelyanov , James Bottomley , Matthew Helsley , aneesh.kumar@linux.vnet.ibm.com, bfields@fieldses.org Subject: Re: [patch 1/9] procfs: Move /proc/pid/fd[info] handling code to fd.[ch] Message-ID: <20120825194325.GG19184@moon> References: <20120823104323.040550004@openvz.org> <20120823104725.592602491@openvz.org> <20120825171605.GT23464@ZenIV.linux.org.uk> <20120825173958.GC19184@moon> <20120825175504.GU23464@ZenIV.linux.org.uk> <20120825185829.GE19184@moon> <20120825191218.GV23464@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120825191218.GV23464@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3335 Lines: 103 On Sat, Aug 25, 2012 at 08:12:18PM +0100, Al Viro wrote: > On Sat, Aug 25, 2012 at 10:58:29PM +0400, Cyrill Gorcunov wrote: > > On Sat, Aug 25, 2012 at 06:55:04PM +0100, Al Viro wrote: > > > > Well, this could be simplified indeed, if I understand you correctly > > > > you propose just save f_mode in flexible array and use it instead > > > > of struct file, right? (which will require to rewrite code a bit) > > > > > > Yes. FWIW, proc_fill_cache() is really atrocious ;-/ Not to mention > > > > OK, thanks. I'm putting this cleanup task in my big todo list. Hope I'll > > manage on the next week with it. > > > > > anything else, if we ever get a negative dentry there, we have a dentry > > > leak. I don't think it's possible in practice, but... Furthermore, > > > > could you please elaborate, you mean this string? > > I mean that if we get to that if (... || !child->d_inode) and end up > evaluating the last part at all, we have acquired a reference to that > struct dentry. And if that last part ends up being true (i.e. if it's > a negative dentry), we'll return from function without having dropped > the reference we'd acquired. Would the patch below improve the code? Look, I've not dropped find_inode_number call since it's a bit unclear for me what would happen if !child case hit child = d_lookup(dir, &qname); if (!child) { struct dentry *new = d_alloc(dir, &qname); if (new) { child = instantiate(dir->d_inode, new, task, ptr); if (child) dput(new); else child = new; } } can we be sure that i_ino won't be zero here? --- fs/proc/base.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) Index: linux-2.6.git/fs/proc/base.c =================================================================== --- linux-2.6.git.orig/fs/proc/base.c +++ linux-2.6.git/fs/proc/base.c @@ -1650,7 +1650,6 @@ int proc_fill_cache(struct file *filp, v instantiate_t instantiate, struct task_struct *task, const void *ptr) { struct dentry *child, *dir = filp->f_path.dentry; - struct inode *inode; struct qstr qname; ino_t ino = 0; unsigned type = DT_UNKNOWN; @@ -1661,8 +1660,7 @@ int proc_fill_cache(struct file *filp, v child = d_lookup(dir, &qname); if (!child) { - struct dentry *new; - new = d_alloc(dir, &qname); + struct dentry *new = d_alloc(dir, &qname); if (new) { child = instantiate(dir->d_inode, new, task, ptr); if (child) @@ -1671,19 +1669,20 @@ int proc_fill_cache(struct file *filp, v child = new; } } - if (!child || IS_ERR(child) || !child->d_inode) - goto end_instantiate; - inode = child->d_inode; - if (inode) { - ino = inode->i_ino; - type = inode->i_mode >> 12; - } + if (IS_ERR_OR_NULL(child)) + goto err; + if (!child->d_inode) + goto err_put; + ino = child->d_inode->i_ino; + type = child->d_inode->i_mode >> 12; +err_put: dput(child); -end_instantiate: - if (!ino) +err: + if (!ino) { ino = find_inode_number(dir, &qname); - if (!ino) - ino = 1; + if (!ino) + ino = 1; + } return filldir(dirent, name, len, filp->f_pos, ino, type); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/