From: Paul Fulghum <paulkf@microgate.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
gregkh@linuxfoundation.org, jslaby@suse.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tty/n_hdlc: fix sleep in !TASK_RUNNING state warning
Date: Wed, 2 Jan 2019 12:55:39 -0800 [thread overview]
Message-ID: <64B85AC0-CEB5-4F11-8B83-3C2A2CD056FB@microgate.com> (raw)
In-Reply-To: <cf9b7323-da1c-20cd-4d50-1080fbe52467@i-love.sakura.ne.jp>
> On Jan 2, 2019, at 7:04 AM, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
>
> On 2019/01/01 12:11, Paul Fulghum wrote:
>> NAK to this patch. It causes lost wakeups in both read and write paths.
>>
>> The write path does not need changing.
>>
>> The read path can be fixed by setting current to TASK_RUNNING at the top of the if (rbuf) block
>> so the warning is not triggered by copy_to_user(). If this block runs the condition is satisfied
>> and it breaks out of the polling loop where it is already being set to TASK_RUNNING and removed
>> from the wait queue. This particular path just needs to account for the copy_to_user which occurs
>> before breaking out.
>>
>> I’ll make a patch to do this when I have the ability to test it in a day or two.
>>
>
> OK. Then, any chance it is rewritten using wait_event_interruptible() in order to reduce lines?
> ( wait_event_interruptible() automatically calls might_sleep(), but is it acceptable for you? )
>
This looks good to me. I applied it and tested blocking (sleep/no sleep) and non-blocking (success/EAGAIN) paths for both read and write.
next prev parent reply other threads:[~2019-01-02 20:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-29 0:41 WARNING in __might_sleep (2) syzbot
2018-12-29 11:48 ` [PATCH] tty/n_hdlc: fix sleep in !TASK_RUNNING state warning Tetsuo Handa
2019-01-01 3:13 ` Paul Fulghum
2019-01-01 20:28 ` [PATCH] tty/n_hdlc: fix __might_sleep warning Paul Fulghum
2019-01-10 11:38 ` Tetsuo Handa
2019-01-10 12:25 ` Arnd Bergmann
[not found] ` <FEBFE826-8D27-4A0B-86A5-BA559921CADC@microgate.com>
2019-01-02 15:04 ` [PATCH] tty/n_hdlc: fix sleep in !TASK_RUNNING state warning Tetsuo Handa
2019-01-02 20:55 ` Paul Fulghum [this message]
2019-01-03 9:09 ` Jiri Slaby
2019-01-03 11:32 ` Tetsuo Handa
2019-01-03 15:57 ` Paul Fulghum
2019-01-04 10:23 ` Tetsuo Handa
2019-01-04 13:57 ` Paul Fulghum
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