From: Greg KH <gregkh@linuxfoundation.org>
To: "Zhang, Qiang" <Qiang.Zhang@windriver.com>
Cc: "zaitcev@redhat.com" <zaitcev@redhat.com>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: 回复: [PATCH] USB: usblp: Add device status detection in usblp_poll()
Date: Mon, 1 Mar 2021 09:32:59 +0100 [thread overview]
Message-ID: <YDymu1AlS+8UjdXG@kroah.com> (raw)
In-Reply-To: <BYAPR11MB263268B5FD6EB3C3B80B63FBFF9A9@BYAPR11MB2632.namprd11.prod.outlook.com>
On Mon, Mar 01, 2021 at 08:26:22AM +0000, Zhang, Qiang wrote:
>
>
> ________________________________________
> 发件人: Greg KH <gregkh@linuxfoundation.org>
> 发送时间: 2021年3月1日 16:00
> 收件人: Zhang, Qiang
> 抄送: zaitcev@redhat.com; linux-usb@vger.kernel.org
> 主题: Re: [PATCH] USB: usblp: Add device status detection in usblp_poll()
>
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On Mon, Mar 01, 2021 at 12:03:00PM +0800, qiang.zhang@windriver.com wrote:
> > From: Zqiang <qiang.zhang@windriver.com>
> >
> > If usblp device has been disconnected, direct return
> > 'EPOLLHUP | EPOLLERR' in usblp_poll().
> >
> >Why? What problem are you solving here? Is this fixing an >older
> >commit, if so, what one?
> >
>
> There is not need fix older commit.
> After the device is disconnected, if the userspace call poll/select() function, will block and never be awakened .
If the device is disconnected, how can the file be opened at all?
Shouldn't it have been torn down already?
And now you are holding a lock across some poll_wait() calls, is that
going to cause problems?
thanks,
greg k-h
next prev parent reply other threads:[~2021-03-01 8:33 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 4:03 [PATCH] USB: usblp: Add device status detection in usblp_poll() qiang.zhang
2021-03-01 8:00 ` Greg KH
2021-03-01 8:26 ` 回复: " Zhang, Qiang
2021-03-01 8:32 ` Greg KH [this message]
2021-03-01 8:52 ` 回复: " Zhang, Qiang
2021-03-02 7:04 ` Greg KH
2021-03-02 7:41 ` 回复: " Zhang, Qiang
2021-03-03 5:12 ` Pete Zaitcev
2021-03-03 6:12 ` 回复: " Zhang, Qiang
2021-03-03 6:56 ` Greg KH
2021-03-03 7:15 ` Zhang, Qiang
2021-03-03 15:57 ` Pete Zaitcev
2021-03-03 17:13 ` Alan Stern
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