Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761345AbXHPOuN (ORCPT ); Thu, 16 Aug 2007 10:50:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760825AbXHPOty (ORCPT ); Thu, 16 Aug 2007 10:49:54 -0400 Received: from hancock.steeleye.com ([71.30.118.248]:51951 "EHLO hancock.sc.steeleye.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760785AbXHPOtx (ORCPT ); Thu, 16 Aug 2007 10:49:53 -0400 Subject: Re: [PATCH] make attribute_container_unregister() unconditionally wait for list empty From: James Bottomley To: James.Smart@Emulex.Com Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <1187193282.3327.21.camel@localhost.localdomain> References: <1187192400.3142.6.camel@localhost.localdomain> <1187193282.3327.21.camel@localhost.localdomain> Content-Type: text/plain Date: Thu, 16 Aug 2007 09:49:47 -0500 Message-Id: <1187275787.3367.25.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.3 (2.10.3-2.fc7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4869 Lines: 139 On Wed, 2007-08-15 at 10:54 -0500, James Bottomley wrote: > This is the patch I've been testing. Actually, that patch was wrong ... it has two subtle bugs that conspire to make it seem correct. Can you try this one instead? I don't have any fibre equipment, and the other transport classes aren't in use when they're released. Thanks, James Index: BUILD-2.6/drivers/base/attribute_container.c =================================================================== --- BUILD-2.6.orig/drivers/base/attribute_container.c 2007-08-15 12:09:32.000000000 -0500 +++ BUILD-2.6/drivers/base/attribute_container.c 2007-08-15 18:01:44.000000000 -0500 @@ -19,9 +19,16 @@ #include #include #include +#include +#include #include "base.h" +static DECLARE_WAIT_QUEUE_HEAD(busy_containers_waitq); + +/* wait up to 30s for containers being unregistered to become free */ +#define BUSY_CONTAINERS_TIMEOUT (30*HZ) + /* This is a private structure used to tie the classdev and the * container .. it should never be visible outside this file */ struct internal_container { @@ -86,29 +93,58 @@ attribute_container_register(struct attr } EXPORT_SYMBOL_GPL(attribute_container_register); +static int +attribute_container_in_use(struct attribute_container *cont) +{ + int retval; + + spin_lock(&cont->containers.k_lock); + retval = !list_empty(&cont->containers.k_list); + spin_unlock(&cont->containers.k_lock); + + return retval; +} /** * attribute_container_unregister - remove a container registration * * @cont: previously registered container to remove + * + * May return -EBUSY if the container still contains live attributes + * that cannot be released. */ int attribute_container_unregister(struct attribute_container *cont) { int retval = -EBUSY; mutex_lock(&attribute_container_mutex); - spin_lock(&cont->containers.k_lock); - if (!list_empty(&cont->containers.k_list)) + if (attribute_container_in_use(cont)) goto out; retval = 0; list_del(&cont->node); out: - spin_unlock(&cont->containers.k_lock); mutex_unlock(&attribute_container_mutex); return retval; } EXPORT_SYMBOL_GPL(attribute_container_unregister); +/** + * attribute_container_unregister_and_wait - remove a container registration + * + * @cont: previously registered container to remove + * + * Waits for everything to be released before returning. + */ +void +attribute_container_unregister_and_wait(struct attribute_container *cont) +{ + while (attribute_container_unregister(cont) == -EBUSY) + WARN_ON(wait_event_timeout(busy_containers_waitq, + !attribute_container_in_use(cont), + BUSY_CONTAINERS_TIMEOUT) == 0); +} +EXPORT_SYMBOL_GPL(attribute_container_unregister_and_wait); + /* private function used as class release */ static void attribute_container_release(struct class_device *classdev) { @@ -227,6 +263,8 @@ attribute_container_remove_device(struct if (dev != ic->classdev.dev) continue; klist_del(&ic->node); + if (!attribute_container_in_use(cont)) + wake_up(&busy_containers_waitq); if (fn) fn(cont, dev, &ic->classdev); else { Index: BUILD-2.6/include/linux/attribute_container.h =================================================================== --- BUILD-2.6.orig/include/linux/attribute_container.h 2007-08-15 12:09:32.000000000 -0500 +++ BUILD-2.6/include/linux/attribute_container.h 2007-08-15 15:59:14.000000000 -0500 @@ -37,6 +37,7 @@ attribute_container_set_no_classdevs(str int attribute_container_register(struct attribute_container *cont); int attribute_container_unregister(struct attribute_container *cont); +void attribute_container_unregister_and_wait(struct attribute_container *cont); void attribute_container_create_device(struct device *dev, int (*fn)(struct attribute_container *, struct device *, Index: BUILD-2.6/include/linux/transport_class.h =================================================================== --- BUILD-2.6.orig/include/linux/transport_class.h 2007-08-15 12:09:32.000000000 -0500 +++ BUILD-2.6/include/linux/transport_class.h 2007-08-15 15:59:14.000000000 -0500 @@ -86,9 +86,9 @@ static inline int transport_container_re return attribute_container_register(&tc->ac); } -static inline int transport_container_unregister(struct transport_container *tc) +static inline void transport_container_unregister(struct transport_container *tc) { - return attribute_container_unregister(&tc->ac); + attribute_container_unregister_and_wait(&tc->ac); } int transport_class_register(struct transport_class *); - 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/