linux-kernel - Re: [PATCH] virtio: console: fix lost wakeup when device is written and polled

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <568c03e9-b30d-4655-8771-f8995f5a4ed4@app.fastmail.com>
Date: Mon, 15 Dec 2025 11:48:47 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: "Lorenz Bauer" <lmb@...valent.com>, "Amit Shah" <amit@...nel.org>,
 "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Cc: virtualization@...ts.linux.dev, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH] virtio: console: fix lost wakeup when device is written and polled

On Mon, Dec 15, 2025, at 11:40, Lorenz Bauer wrote:
> +	}
> +	if (freed) {
> +		/* We freed all used buffers. Issue a wake up so that other pending
> +		 * tasks do not get stuck. This is necessary because vring_interrupt()
> +		 * will drop wakeups from the host if there are no used buffers.
> +		 */
>  		port->outvq_full = false;
> +		wake_up_interruptible(&port->waitqueue);
>  	}

Is it always enough to wake up only one waiter? From your
description it sounds like it might need wake_up_interruptible_all()
instead, but I may be misunderstanding the issue.

       Arnd