From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Greg KH <greg@kroah.com>
Cc: Colin Ian King <colin.king@canonical.com>,
Oliver Neukum <oneukum@suse.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: Thu, 21 May 2020 19:01:13 +0900 [thread overview]
Message-ID: <177cc23a-60a7-f5cd-09d6-57608727ea27@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20200521073323.GA2579717@kroah.com>
On 2020/05/21 16:33, Greg KH wrote:
> On Thu, May 21, 2020 at 08:31:29AM +0900, Tetsuo Handa wrote:
>> Since e.g. wdm_flush() calls wait_event() on WDM_IN_USE bit,
>> make sure to call wake_up_all() when clearing WDM_IN_USE bit.
>
> I'm sorry, but I don't understand what this changelog text is trying to
> say. Can you reword this differently?
wait_event("condition") wants corresponding wake_up() (or its variant)
after making "condition" == true. For example, wdm_flush() calls
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.
> 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.
next prev parent reply other threads:[~2020-05-21 10:01 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 [this message]
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
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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