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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Oliver Neukum <oneukum@suse.com>, Greg KH <greg@kroah.com>
Cc: Colin Ian King <colin.king@canonical.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-usb@vger.kernel.org
Subject: Re: [PATCH] USB: cdc-wdm: Call wake_up_all() when clearing WDM_IN_USE bit.
Date: Fri, 22 May 2020 07:48:54 +0900	[thread overview]
Message-ID: <a72cbcc6-df68-2043-1580-a8b4e4053079@i-love.sakura.ne.jp> (raw)
In-Reply-To: <1590090636.6470.12.camel@suse.com>

On 2020/05/22 4:50, Oliver Neukum wrote:
> interesting. Do you have a test case for these patches working?

No.

> 
>> 	wait_event(desc->wait,
>> 			/*
>> 			 * needs both flags. We cannot do with one
>> 			 * because resetting it would cause a race
>> 			 * with write() yet we need to signal
>> 			 * a disconnect
>> 			 */
>> 			!test_bit(WDM_IN_USE, &desc->flags) ||
>> 			test_bit(WDM_DISCONNECTING, &desc->flags));
>>
>> but wdm_write() is not calling wake_up(&desc->wait) after
>> clear_bit(WDM_IN_USE, &desc->flags) when usb_submit_urb() failed.
> 
> Yes, because desc->wlock is held. There can be nobody sleeping here.

Then, this patch is not needed. (But adding some comment is welcomed.)

> 
>>> And is this a bugfix?  For what?  Does it need to go to stable kernels?
>>
>> Potential bugfix. syzbot is reporting two bugs that hung at wdm_flush(),
>> but I think that this patch won't fix these bugs. Therefore, I don't think
>> this patch needs to go to stable kernels.
> 
> Do you have links for them?

It turned out that the second bug report is a duplicate of the first bug report.
The dashboard link for the first bug report is
https://syzkaller.appspot.com/bug?id=e7b761593b23eb50855b9ea31e3be5472b711186 .

  reply	other threads:[~2020-05-21 22:49 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 [this message]
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
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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