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;
Date:   Mon, 28 Oct 2019 09:30:41 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Xiang Zheng <zhengxiang9@huawei.com>
Cc:     bhelgaas@google.com, wangxiongfeng2@huawei.com,
        wanghaibin.wang@huawei.com, guoheyi@huawei.com,
        yebiaoxiang@huawei.com, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, rjw@rjwysocki.net,
        tglx@linutronix.de, guohanjun@huawei.com, yangyingliang@huawei.com
Subject: Re: [PATCH] pci: lock the pci_cfg_wait queue for the consistency of
 data
Message-ID: <20191028163041.GA8257@bombadil.infradead.org>
References: <20191028091809.35212-1-zhengxiang9@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20191028091809.35212-1-zhengxiang9@huawei.com>
User-Agent: Mutt/1.12.1 (2019-06-15)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Oct 28, 2019 at 05:18:09PM +0800, Xiang Zheng wrote:
> 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().

As I said earlier, this reintroduces the deadlock addressed by
cdcb33f9824429a926b971bf041a6cec238f91ff