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From: Alan Stern <stern@rowland.harvard.edu>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Andrey Konovalov <andreyknvl@google.com>,
	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: Fri, 29 May 2020 21:10:40 -0400	[thread overview]
Message-ID: <20200530011040.GB12419@rowland.harvard.edu> (raw)
In-Reply-To: <79ba410f-e0ef-2465-b94f-6b9a4a82adf5@i-love.sakura.ne.jp>

On Sat, May 30, 2020 at 09:42:46AM +0900, Tetsuo Handa wrote:
> On 2020/05/30 5:41, Andrey Konovalov wrote:
> > On Thu, May 28, 2020 at 10:58 PM Alan Stern <stern@rowland.harvard.edu> wrote:

> >> This sounds like a bug in the driver.  What would it do if someone had a
> >> genuine (not emulated) but buggy USB device which didn't send the
> >> desired response?  The only way to unblock the driver would be to unplug
> >> the device!  That isn't acceptable behavior.
> > 
> > OK, that's what I thought.
> 
> I believe that this is not a bug in the driver but a problem of hardware
> failure. Unless this is high-availability code which is designed for safely
> failing over to other node, we don't need to care about hardware failure.

Oh my!  I can't even imagine what Linus would say if he saw that...  :-(

Have you heard of Bad USB?

The kernel most definitely does need to protect itself against 
misbehaving hardware.  Let's just leave it at that.  If you don't 
believe me, ask Greg KH.

I admit, causing a driver to hang isn't the worst thing a buggy device 
can do.  But the kernel is supposed to be able to cope with such things 
gracefully.

Alan Stern

  reply	other threads:[~2020-05-30  1:10 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
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 [this message]
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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