Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Xiang Zheng <zhengxiang9@huawei.com>
To:     <bhelgaas@google.com>
CC:     <zhengxiang9@huawei.com>, <wangxiongfeng2@huawei.com>,
        <wanghaibin.wang@huawei.com>, <guoheyi@huawei.com>,
        <yebiaoxiang@huawei.com>, <linux-pci@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <willy@infradead.org>,
        <rjw@rjwysocki.net>, <tglx@linutronix.de>, <guohanjun@huawei.com>,
        <yangyingliang@huawei.com>
Subject: [PATCH] pci: lock the pci_cfg_wait queue for the consistency of data
Date:   Mon, 28 Oct 2019 17:18:09 +0800
Message-ID: <20191028091809.35212-1-zhengxiang9@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Commit "7ea7e98fd8d0" suggests that the "pci_lock" is sufficient,
and all the callers of pci_wait_cfg() are wrapped with the "pci_lock".

However, since the commit "cdcb33f98244" merged, the accesses to
the pci_cfg_wait queue are not safe anymore. A "pci_lock" is
insufficient and we need to hold an additional queue lock while
read/write the wait queue.

So let's use the add_wait_queue()/remove_wait_queue() instead of
__add_wait_queue()/__remove_wait_queue().

Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
Cc: Heyi Guo <guoheyi@huawei.com>
Cc: Biaoxiang Ye <yebiaoxiang@huawei.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
---
 drivers/pci/access.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 2fccb5762c76..247bf36e0047 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -207,14 +207,14 @@ static noinline void pci_wait_cfg(struct pci_dev *dev)
 {
 	DECLARE_WAITQUEUE(wait, current);
 
-	__add_wait_queue(&pci_cfg_wait, &wait);
+	add_wait_queue(&pci_cfg_wait, &wait);
 	do {
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		raw_spin_unlock_irq(&pci_lock);
 		schedule();
 		raw_spin_lock_irq(&pci_lock);
 	} while (dev->block_cfg_access);
-	__remove_wait_queue(&pci_cfg_wait, &wait);
+	remove_wait_queue(&pci_cfg_wait, &wait);
 }
 
 /* Returns 0 on success, negative values indicate error. */
-- 
2.19.1