From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga02-in.huawei.com ([119.145.14.65]:52728 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755259Ab2ISCmH (ORCPT ); Tue, 18 Sep 2012 22:42:07 -0400 From: Yijing Wang To: Bjorn Helgaas , Huang Ying , Chen Gong CC: , Hanjun Guo , , Yijing Wang Subject: [PATCH 2/6] PCI/AER: introduce pci_bus_ops_get() function to avoid a small race condition window Date: Wed, 19 Sep 2012 10:40:38 +0800 Message-ID: <1348022442-7816-3-git-send-email-wangyijing@huawei.com> In-Reply-To: <1348022442-7816-1-git-send-email-wangyijing@huawei.com> References: <1348022442-7816-1-git-send-email-wangyijing@huawei.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-pci-owner@vger.kernel.org List-ID: When we rmmod aer_inject module, there is a race condition window between pci_bus_ops_pop() and pci_bus_set_ops() in aer_inject_exit, eg. pci_read_aer/pci_write_aer was called between them. So introduce pci_bus_ops_get() to avoid this. Signed-off-by: Yijing Wang --- drivers/pci/pcie/aer/aer_inject.c | 21 ++++++++++++++++++--- 1 files changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/pci/pcie/aer/aer_inject.c b/drivers/pci/pcie/aer/aer_inject.c index 0f00a27..442147b 100644 --- a/drivers/pci/pcie/aer/aer_inject.c +++ b/drivers/pci/pcie/aer/aer_inject.c @@ -67,6 +67,8 @@ struct pci_bus_ops { struct pci_ops *ops; }; +#define to_pci_bus_ops(n) container_of(n, struct pci_bus_ops, list) + static LIST_HEAD(einjected); static LIST_HEAD(pci_bus_ops_list); @@ -160,6 +162,18 @@ static struct pci_bus_ops *pci_bus_ops_pop(void) return bus_ops; } +static struct pci_bus_ops *pci_bus_ops_get(struct pci_bus_ops *from) +{ + struct pci_bus_ops *bus_ops = NULL; + struct list_head *n; + + n = from ? from->list.next : pci_bus_ops_list.next; + if (n != &pci_bus_ops_list) + bus_ops = to_pci_bus_ops(n); + + return bus_ops; +} + static u32 *find_pci_config_dword(struct aer_error *err, int where, int *prw1cs) { @@ -540,14 +554,15 @@ static void __exit aer_inject_exit(void) { struct aer_error *err, *err_next; unsigned long flags; - struct pci_bus_ops *bus_ops; + struct pci_bus_ops *bus_ops = NULL; misc_deregister(&aer_inject_device); - while ((bus_ops = pci_bus_ops_pop())) { + while ((bus_ops = pci_bus_ops_get(bus_ops))) pci_bus_set_ops(bus_ops->bus, bus_ops->ops); + + while ((bus_ops = pci_bus_ops_pop())) kfree(bus_ops); - } spin_lock_irqsave(&inject_lock, flags); list_for_each_entry_safe(err, err_next, &einjected, list) { -- 1.7.1