linux-kernel - Re: [PATCH 1/5] seccomp: don't use semaphore and wait

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Message-ID: <Y8AgC99AUeMjFWKt@tycho.pizza>
Date:   Thu, 12 Jan 2023 07:58:19 -0700
From:   Tycho Andersen <tycho@...ho.pizza>
To:     Andrei Vagin <avagin@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Christian Brauner <brauner@...nel.org>,
        Andrei Vagin <avagin@...il.com>,
        Andy Lutomirski <luto@...capital.net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Peter Oskolkov <posk@...gle.com>,
        Will Drewry <wad@...omium.org>
Subject: Re: [PATCH 1/5] seccomp: don't use semaphore and wait_queue together

On Tue, Jan 10, 2023 at 01:30:06PM -0800, Andrei Vagin wrote:
> From: Andrei Vagin <avagin@...il.com>
> 
> The main reason is to use new wake_up helpers that will be added in the
> following patches. But here are a few other reasons:
> 
> * if we use two different ways, we always need to call them both. This
>   patch fixes seccomp_notify_recv where we forgot to call wake_up_poll
>   in the error path.

[snip]

> @@ -1515,7 +1546,8 @@ static long seccomp_notify_recv(struct seccomp_filter *filter,
>  			if (should_sleep_killable(filter, knotif))
>  				complete(&knotif->ready);
>  			knotif->state = SECCOMP_NOTIFY_INIT;
> -			up(&filter->notif->request);
> +			atomic_add(1, &filter->notif->requests);
> +			wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);
>  		}
>  		mutex_unlock(&filter->notify_lock);
>  	}

I wonder if this shouldn't be a separate patch that you can send now
independent of this series?

Tycho