linux-kernel - [PATCH v5 2/5] PCI/AER: use list_for_each_entry to avoid a small race condition window

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Date:	Tue, 26 Mar 2013 10:43:36 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Tony Luck <tony.luck@...el.com>
CC:	<linux-kernel@...r.kernel.org>, Hanjun Guo <guohanjun@...wei.com>,
	Yijing Wang <wangyijing@...wei.com>
Subject: [PATCH v5 2/5] PCI/AER: use list_for_each_entry to avoid a small race condition window

When we rmmod aer_inject module, there is a small 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 keep pci_bus_ops_list until pci_bus_set_ops complete, use list_for_each_entry() instead of
pci_bus_ops_pop to get bus_ops.

Signed-off-by: Yijing Wang <wangyijing@...wei.com>
---
 drivers/pci/pcie/aer/aer_inject.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/aer/aer_inject.c b/drivers/pci/pcie/aer/aer_inject.c
index fdab3bb..f499f01 100644
--- a/drivers/pci/pcie/aer/aer_inject.c
+++ b/drivers/pci/pcie/aer/aer_inject.c
@@ -543,10 +543,11 @@ static void __exit aer_inject_exit(void)
 
 	misc_deregister(&aer_inject_device);
 
-	while ((bus_ops = pci_bus_ops_pop())) {
+	list_for_each_entry(bus_ops, &pci_bus_ops_list, list)
 		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


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