From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751480AbWIZFku (ORCPT ); Tue, 26 Sep 2006 01:40:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751519AbWIZFkq (ORCPT ); Tue, 26 Sep 2006 01:40:46 -0400 Received: from mail.suse.de ([195.135.220.2]:4322 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1751479AbWIZFke (ORCPT ); Tue, 26 Sep 2006 01:40:34 -0400 From: Greg KH To: linux-kernel@vger.kernel.org Cc: Alan Stern , Greg Kroah-Hartman Subject: [PATCH 47/47] Driver core: Don't call put methods while holding a spinlock Date: Mon, 25 Sep 2006 22:38:07 -0700 Message-Id: <11592492364054-git-send-email-greg@kroah.com> X-Mailer: git-send-email 1.4.2.1 In-Reply-To: <1159249232139-git-send-email-greg@kroah.com> References: <20060926053728.GA8970@kroah.com> <1159249087369-git-send-email-greg@kroah.com> <11592490903867-git-send-email-greg@kroah.com> <11592490933346-git-send-email-greg@kroah.com> <1159249096460-git-send-email-greg@kroah.com> <11592490993970-git-send-email-greg@kroah.com> <11592491023995-git-send-email-greg@kroah.com> <1159249104512-git-send-email-greg@kroah.com> <11592491082990-git-send-email-greg@kroah.com> <1159249111668-git-send-email-greg@kroah.com> <11592491152668-git-send-email-greg@kroah.com> <115924911859-git-send-email-greg@kroah.com> <11592491211162-git-send-email-greg@kroah.com> <1159249124371-git-send-email-greg@kroah.com> <11592491274168-git-send-email-greg@kroah.com> <11592491303012-git-send-email-greg@kroah.com> <11592491342421-git-send-email-greg@kroah.com> <11592491371254-git-send-email-greg@kroah.com> <1159249140339-git-send-email-greg@kroah.com> <11592491451786-git-send-email-greg@kroah.com> <11592491482560-git-send-email-greg@kroah.com> <11592491512 235-git-send-email-greg@kroah.com> <11592491551919-git-send-email-greg@kroah.com> <11592491581007-git-send-email-greg@kroah.com> <11592491611339-git-send-email-greg@kroah.com> <11592491643725-git-send-email-greg@kroah.com> <11592491672052-git-send-email-greg@kroah.com> <11592491704137-git-send-email-greg@kroah.com> <11592491744040-git-send-email-greg@kroah.com> <1159249177618-git-send-email-greg@kroah.com> <11592491803904-git-send-email-greg@kroah.com> <11592491833450-git-send-email-greg@kroah.com> <11592491862904-git-send-email-greg@kroah.com> <11592491901464-git-send-email-greg@kroah.com> <11592491924093-git-send-email-greg@kroah.com> <1159249196427-git-send-email-greg@kroah.com> <1159249200793-git-send-email-greg@kroah.com> <11592492023883-git-send-email-greg@kroah.com> <11592492061208-git-send-email-greg@kroah.com> <1159249209773-git-send-email-greg@kroah.com> <11592492123695-git-send-email-greg@kroah.com> <11592492153066-git-send-email-greg@kroah.com> <11592492193773-gi t-send-email-greg@kroah.com> <11592492221573-git-send-email-greg@kroah.com> <1159249226922-git-send-email-greg@kroah.com> <115924922922-git-send-email-greg@kroah.com> <1159249232139-git-send-email-greg@kroah.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Alan Stern The klist utility routines currently call _put methods while holding a spinlock. This is of course illegal; a put routine could try to unregister a device and hence need to sleep. No problems have arisen until now because in many cases klist removals were done synchronously, so the _put methods were never actually used. In other cases we may simply have been lucky. This patch (as784) reworks the klist routines so that _put methods are called only _after_ the klist's spinlock has been released. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- lib/klist.c | 26 +++++++++++++++----------- 1 files changed, 15 insertions(+), 11 deletions(-) diff --git a/lib/klist.c b/lib/klist.c index 9c94f0b..120bd17 100644 --- a/lib/klist.c +++ b/lib/klist.c @@ -123,12 +123,10 @@ EXPORT_SYMBOL_GPL(klist_add_tail); static void klist_release(struct kref * kref) { struct klist_node * n = container_of(kref, struct klist_node, n_ref); - void (*put)(struct klist_node *) = n->n_klist->put; + list_del(&n->n_node); complete(&n->n_removed); n->n_klist = NULL; - if (put) - put(n); } static int klist_dec_and_del(struct klist_node * n) @@ -145,10 +143,14 @@ static int klist_dec_and_del(struct klis void klist_del(struct klist_node * n) { struct klist * k = n->n_klist; + void (*put)(struct klist_node *) = k->put; spin_lock(&k->k_lock); - klist_dec_and_del(n); + if (!klist_dec_and_del(n)) + put = NULL; spin_unlock(&k->k_lock); + if (put) + put(n); } EXPORT_SYMBOL_GPL(klist_del); @@ -161,10 +163,7 @@ EXPORT_SYMBOL_GPL(klist_del); void klist_remove(struct klist_node * n) { - struct klist * k = n->n_klist; - spin_lock(&k->k_lock); - klist_dec_and_del(n); - spin_unlock(&k->k_lock); + klist_del(n); wait_for_completion(&n->n_removed); } @@ -260,12 +259,15 @@ static struct klist_node * to_klist_node struct klist_node * klist_next(struct klist_iter * i) { struct list_head * next; + struct klist_node * lnode = i->i_cur; struct klist_node * knode = NULL; + void (*put)(struct klist_node *) = i->i_klist->put; spin_lock(&i->i_klist->k_lock); - if (i->i_cur) { - next = i->i_cur->n_node.next; - klist_dec_and_del(i->i_cur); + if (lnode) { + next = lnode->n_node.next; + if (!klist_dec_and_del(lnode)) + put = NULL; } else next = i->i_head->next; @@ -275,6 +277,8 @@ struct klist_node * klist_next(struct kl } i->i_cur = knode; spin_unlock(&i->i_klist->k_lock); + if (put && lnode) + put(lnode); return knode; } -- 1.4.2.1