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From: Alan Stern <stern@rowland.harvard.edu>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Oliver Neukum <oneukum@suse.com>,
	Colin Ian King <colin.king@canonical.com>,
	Arnd Bergmann <arnd@arndb.de>,
	USB list <linux-usb@vger.kernel.org>,
	syzbot <syzbot+854768b99f19e89d7f81@syzkaller.appspotmail.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH] USB: cdc-wdm: Call wake_up_all() when clearing WDM_IN_USE bit.
Date: Thu, 28 May 2020 15:40:57 -0400	[thread overview]
Message-ID: <20200528194057.GA21709@rowland.harvard.edu> (raw)
In-Reply-To: <CAAeHK+ww0u0G94z_Y7VXLCVTQVZ9thO0q69n+Fj3jKT6MtpPng@mail.gmail.com>

On Thu, May 28, 2020 at 09:03:43PM +0200, Andrey Konovalov wrote:

> Ah, so the problem is that when a process exits, it tries to close wdm
> fd first, which ends up calling wdm_flush(), which can't finish
> because the USB requests are not terminated before raw-gadget fd is
> closed, which is supposed to happen after wdm fd is closed. Is this
> correct? I wonder what will happen if a real device stays connected
> and ignores wdm requests.
> 
> I don't understand though, how using wait_event_interruptible() will
> shadow anything here.
> 
> Alan, Greg, is this acceptable behavior for a USB driver?

I don't understand what the problem is.  Can you explain in more general 
terms -- nothing specific to wdm or anything like that -- what you are 
concerned about?  Is this something that could happen to any gadget 
driver?  Or any USB class device driver?  Or does it only affect 
usespace components of raw-gadget drivers?

Alan Stern

  reply	other threads:[~2020-05-28 19:41 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20 23:31 [PATCH] USB: cdc-wdm: Call wake_up_all() when clearing WDM_IN_USE bit Tetsuo Handa
2020-05-21  7:33 ` Greg KH
2020-05-21 10:01   ` Tetsuo Handa
2020-05-21 19:50     ` Oliver Neukum
2020-05-21 22:48       ` Tetsuo Handa
2020-05-22  8:04         ` Oliver Neukum
2020-05-22  8:26           ` Tetsuo Handa
2020-05-25 12:06             ` Oliver Neukum
2020-05-25 13:32               ` Tetsuo Handa
2020-05-27  4:47                 ` Tetsuo Handa
2020-05-28 15:18                   ` Andrey Konovalov
2020-05-28 16:03                     ` Tetsuo Handa
2020-05-28 19:03                       ` Andrey Konovalov
2020-05-28 19:40                         ` Alan Stern [this message]
2020-05-28 19:51                           ` Andrey Konovalov
2020-05-28 20:58                             ` Alan Stern
2020-05-29 20:41                               ` Andrey Konovalov
2020-05-30  0:42                                 ` Tetsuo Handa
2020-05-30  1:10                                   ` Alan Stern
2020-05-30  4:58                                     ` Tetsuo Handa
2020-06-24 11:57                                       ` Oliver Neukum
2020-06-24 12:48                                         ` Tetsuo Handa
2020-05-30  6:08                                   ` Greg Kroah-Hartman
2020-06-01 12:26                                   ` Andrey Konovalov
2020-05-30 15:25                               ` Oliver Neukum
2020-05-30 15:47                                 ` Alan Stern
2020-06-08  2:24                                   ` Tetsuo Handa
2020-06-18  0:48                                     ` Tetsuo Handa
2020-06-19 13:56                                       ` Andrey Konovalov
2020-06-23 11:20                                         ` Tetsuo Handa
2020-07-02  5:44                                           ` Tetsuo Handa
2020-07-02  7:24                                             ` Oliver Neukum
2020-07-15  6:15                                               ` Tetsuo Handa
2020-08-10 10:47                                                 ` Tetsuo Handa
2020-09-24 15:09                                                   ` [PATCH] USB: cdc-wdm: Make wdm_flush() interruptible and add wdm_fsync() Tetsuo Handa
2020-09-28 14:17                                                     ` [PATCH (repost)] " Tetsuo Handa
2020-06-25  9:56                                     ` [PATCH] USB: cdc-wdm: Call wake_up_all() when clearing WDM_IN_USE bit Oliver Neukum
2020-06-25 11:15                                       ` Tetsuo Handa
2020-07-01  7:08                                     ` [TEST]Re: " Oliver Neukum

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