From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758230AbZLFXjI (ORCPT ); Sun, 6 Dec 2009 18:39:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758159AbZLFXjE (ORCPT ); Sun, 6 Dec 2009 18:39:04 -0500 Received: from kroah.org ([198.145.64.141]:33847 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758162AbZLFXix (ORCPT ); Sun, 6 Dec 2009 18:38:53 -0500 X-Mailbox-Line: From gregkh@mini.kroah.org Sun Dec 6 15:32:11 2009 Message-Id: <20091206233210.990907937@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Sun, 06 Dec 2009 15:30:51 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Maciej Sosnowski , Jeff Kirsher , "David S. Miller" Subject: [19/20] dca: redesign locks to fix deadlocks References: <20091206233032.387950574@mini.kroah.org> Content-Disposition: inline; filename=dca-redesign-locks-to-fix-deadlocks.patch In-Reply-To: <20091206233711.GA11609@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Maciej Sosnowski commit eb4400e3a040b90a3ad805b01fcbc99a5f615c8f upstream. Change spin_locks to irqsave to prevent dead-locks. Protect adding and deleting to/from dca_providers list. Drop the lock during dca_sysfs_add_req() and dca_sysfs_remove_req() calls as they might sleep (use GFP_KERNEL allocation). Signed-off-by: Maciej Sosnowski Acked-by: Jeff Kirsher Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/dca/dca-core.c | 51 +++++++++++++++++++++++++++++++------------------ 1 file changed, 33 insertions(+), 18 deletions(-) --- a/drivers/dca/dca-core.c +++ b/drivers/dca/dca-core.c @@ -28,7 +28,7 @@ #include #include -#define DCA_VERSION "1.4" +#define DCA_VERSION "1.8" MODULE_VERSION(DCA_VERSION); MODULE_LICENSE("GPL"); @@ -60,16 +60,17 @@ int dca_add_requester(struct device *dev { struct dca_provider *dca; int err, slot = -ENODEV; + unsigned long flags; if (!dev) return -EFAULT; - spin_lock(&dca_lock); + spin_lock_irqsave(&dca_lock, flags); /* check if the requester has not been added already */ dca = dca_find_provider_by_dev(dev); if (dca) { - spin_unlock(&dca_lock); + spin_unlock_irqrestore(&dca_lock, flags); return -EEXIST; } @@ -78,19 +79,21 @@ int dca_add_requester(struct device *dev if (slot >= 0) break; } - if (slot < 0) { - spin_unlock(&dca_lock); + + spin_unlock_irqrestore(&dca_lock, flags); + + if (slot < 0) return slot; - } err = dca_sysfs_add_req(dca, dev, slot); if (err) { - dca->ops->remove_requester(dca, dev); - spin_unlock(&dca_lock); + spin_lock_irqsave(&dca_lock, flags); + if (dca == dca_find_provider_by_dev(dev)) + dca->ops->remove_requester(dca, dev); + spin_unlock_irqrestore(&dca_lock, flags); return err; } - spin_unlock(&dca_lock); return 0; } EXPORT_SYMBOL_GPL(dca_add_requester); @@ -103,25 +106,25 @@ int dca_remove_requester(struct device * { struct dca_provider *dca; int slot; + unsigned long flags; if (!dev) return -EFAULT; - spin_lock(&dca_lock); + spin_lock_irqsave(&dca_lock, flags); dca = dca_find_provider_by_dev(dev); if (!dca) { - spin_unlock(&dca_lock); + spin_unlock_irqrestore(&dca_lock, flags); return -ENODEV; } slot = dca->ops->remove_requester(dca, dev); - if (slot < 0) { - spin_unlock(&dca_lock); + spin_unlock_irqrestore(&dca_lock, flags); + + if (slot < 0) return slot; - } dca_sysfs_remove_req(dca, slot); - spin_unlock(&dca_lock); return 0; } EXPORT_SYMBOL_GPL(dca_remove_requester); @@ -135,17 +138,18 @@ u8 dca_common_get_tag(struct device *dev { struct dca_provider *dca; u8 tag; + unsigned long flags; - spin_lock(&dca_lock); + spin_lock_irqsave(&dca_lock, flags); dca = dca_find_provider_by_dev(dev); if (!dca) { - spin_unlock(&dca_lock); + spin_unlock_irqrestore(&dca_lock, flags); return -ENODEV; } tag = dca->ops->get_tag(dca, dev, cpu); - spin_unlock(&dca_lock); + spin_unlock_irqrestore(&dca_lock, flags); return tag; } @@ -217,11 +221,16 @@ static BLOCKING_NOTIFIER_HEAD(dca_provid int register_dca_provider(struct dca_provider *dca, struct device *dev) { int err; + unsigned long flags; err = dca_sysfs_add_provider(dca, dev); if (err) return err; + + spin_lock_irqsave(&dca_lock, flags); list_add(&dca->node, &dca_providers); + spin_unlock_irqrestore(&dca_lock, flags); + blocking_notifier_call_chain(&dca_provider_chain, DCA_PROVIDER_ADD, NULL); return 0; @@ -234,9 +243,15 @@ EXPORT_SYMBOL_GPL(register_dca_provider) */ void unregister_dca_provider(struct dca_provider *dca) { + unsigned long flags; + blocking_notifier_call_chain(&dca_provider_chain, DCA_PROVIDER_REMOVE, NULL); + + spin_lock_irqsave(&dca_lock, flags); list_del(&dca->node); + spin_unlock_irqrestore(&dca_lock, flags); + dca_sysfs_remove_provider(dca); } EXPORT_SYMBOL_GPL(unregister_dca_provider);