From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760615AbYBLGDg (ORCPT ); Tue, 12 Feb 2008 01:03:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754074AbYBLGD3 (ORCPT ); Tue, 12 Feb 2008 01:03:29 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:48245 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753475AbYBLGD2 (ORCPT ); Tue, 12 Feb 2008 01:03:28 -0500 X-AuthUser: davidel@xmailserver.org Date: Mon, 11 Feb 2008 22:03:21 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Linux Kernel Mailing List cc: Andrew Morton , Vegard Nossum Subject: [patch] avoid kmemcheck warning in epoll Message-ID: X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Epoll calls rb_set_parent(n, n) to initialize the rb-tree node, but rb_set_parent() accesses node's pointer in its code. This creates a warning in kmemcheck (reported by Vegard Nossum) about an uninitialized memory access. The warning is harmless since the following rb-tree node insert is going to overwrite the node data. In any case I think it's better to not have that happening at all, and fix it by simplifying the code to get rid of a few lines that became superfluous after the previous epoll changes. Signed-off-by: Davide Libenzi - Davide --- fs/eventpoll.c | 27 +++------------------------ 1 file changed, 3 insertions(+), 24 deletions(-) Index: linux-2.6.mod/fs/eventpoll.c =================================================================== --- linux-2.6.mod.orig/fs/eventpoll.c 2008-02-11 15:31:02.000000000 -0800 +++ linux-2.6.mod/fs/eventpoll.c 2008-02-11 15:32:46.000000000 -0800 @@ -257,25 +257,6 @@ (p1->file < p2->file ? -1 : p1->fd - p2->fd)); } -/* Special initialization for the RB tree node to detect linkage */ -static inline void ep_rb_initnode(struct rb_node *n) -{ - rb_set_parent(n, n); -} - -/* Removes a node from the RB tree and marks it for a fast is-linked check */ -static inline void ep_rb_erase(struct rb_node *n, struct rb_root *r) -{ - rb_erase(n, r); - rb_set_parent(n, n); -} - -/* Fast check to verify that the item is linked to the main RB tree */ -static inline int ep_rb_linked(struct rb_node *n) -{ - return rb_parent(n) != n; -} - /* Tells us if the item is currently linked */ static inline int ep_is_linked(struct list_head *p) { @@ -283,13 +264,13 @@ } /* Get the "struct epitem" from a wait queue pointer */ -static inline struct epitem * ep_item_from_wait(wait_queue_t *p) +static inline struct epitem *ep_item_from_wait(wait_queue_t *p) { return container_of(p, struct eppoll_entry, wait)->base; } /* Get the "struct epitem" from an epoll queue wrapper */ -static inline struct epitem * ep_item_from_epqueue(poll_table *p) +static inline struct epitem *ep_item_from_epqueue(poll_table *p) { return container_of(p, struct ep_pqueue, pt)->epi; } @@ -411,8 +392,7 @@ list_del_init(&epi->fllink); spin_unlock(&file->f_ep_lock); - if (ep_rb_linked(&epi->rbn)) - ep_rb_erase(&epi->rbn, &ep->rbr); + rb_erase(&epi->rbn, &ep->rbr); spin_lock_irqsave(&ep->lock, flags); if (ep_is_linked(&epi->rdllink)) @@ -728,7 +708,6 @@ goto error_return; /* Item initialization follow here ... */ - ep_rb_initnode(&epi->rbn); INIT_LIST_HEAD(&epi->rdllink); INIT_LIST_HEAD(&epi->fllink); INIT_LIST_HEAD(&epi->pwqlist);