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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Sean Young <sean@mess.org>
Cc: Alan Stern <stern@rowland.harvard.edu>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Jarod Wilson <jarod@redhat.com>,
	syzbot <syzbot+c558267ad910fc494497@syzkaller.appspotmail.com>,
	andreyknvl@google.com, linux-media@vger.kernel.org,
	linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH v2 (resend)] media: imon: reorganize serialization
Date: Mon, 2 May 2022 19:40:36 +0900	[thread overview]
Message-ID: <c0a519b5-22d9-ee55-c28e-777c0856198c@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <e144d930-7b82-3310-1163-dae9f7914fa9@I-love.SAKURA.ne.jp>

On 2022/05/02 19:26, Tetsuo Handa wrote:
> @@ -550,10 +548,15 @@ static int display_open(struct inode *inode, struct file *file)
>  
>  	mutex_unlock(&ictx->lock);
>  
> -	if (retval && refcount_dec_and_test(&ictx->users))
> -		free_imon_context(ictx);
> -
> +	if (retval) {
> +		mutex_unlock(&driver_lock);

Oops. This is mutex_lock(&driver_lock);.

> +		if (refcount_dec_and_test(&ictx->users))
> +			free_imon_context(ictx);
> +		mutex_unlock(&driver_lock);
> +	}
> +	return retval;
>  exit:
> +	mutex_unlock(&driver_lock);
>  	return retval;
>  }
>  

But if you merely want to avoid adding "struct rcu_head rcu;" to "struct imon_context",
we can use synchronize_rcu(); kfree(ictx); sequence (at the cost of waiting for RCU
grace period inside free_imon_context()).


  reply	other threads:[~2022-05-02 10:41 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 13:18 possible deadlock in display_open syzbot
2022-04-25  5:29 ` Tetsuo Handa
2022-04-25  9:20   ` Sean Young
2022-04-25 11:14     ` Tetsuo Handa
2022-04-25 11:56       ` Sean Young
2022-04-25 16:01         ` Alan Stern
2022-04-25 16:21           ` Sean Young
2022-04-26  0:54             ` [PATCH] media: imon: remove redundant serialization Tetsuo Handa
2022-04-26  7:57               ` Sean Young
2022-04-26 10:32                 ` [PATCH v2] media: imon: reorganize serialization Tetsuo Handa
2022-05-02  3:49                   ` [PATCH v2 (resend)] " Tetsuo Handa
2022-05-02  9:39                     ` Sean Young
2022-05-02 10:26                       ` Tetsuo Handa
2022-05-02 10:40                         ` Tetsuo Handa [this message]
2022-05-02 10:46                     ` Oliver Neukum
2022-05-02 11:05                       ` Tetsuo Handa
2022-05-03  7:41                         ` Oliver Neukum
2022-05-02 12:53                     ` Greg KH
2022-05-02 13:04                       ` Tetsuo Handa
2022-05-02 13:06                         ` Greg KH
2022-05-02 13:40                     ` Tetsuo Handa

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