netdev - Re: [PATCH net] net/sched: sch_taprio: properly cancel timer from taprio

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Message-ID: <YVwzgwrW0QttrbFv@dcaratti.users.ipa.redhat.com>
Date:   Tue, 5 Oct 2021 13:14:11 +0200
From:   Davide Caratti <dcaratti@...hat.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net] net/sched: sch_taprio: properly cancel timer from
 taprio_destroy()

hello Eric, thanks for the patch!

On Mon, Oct 04, 2021 at 12:55:22PM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> There is a comment in qdisc_create() about us not calling ops->reset()
> in some cases.
> 
> err_out4:
> 	/*
> 	 * Any broken qdiscs that would require a ops->reset() here?
> 	 * The qdisc was never in action so it shouldn't be necessary.
> 	 */

right, I didn't spot this error path.
 
 
> Fixes: 44d4775ca518 ("net/sched: sch_taprio: reset child qdiscs before freeing them")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Davide Caratti <dcaratti@...hat.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>


Acked-by: Davide Caratti <dcaratti@...hat.com>

> ---
>  net/sched/sch_taprio.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
> index 1ab2fc933a214d04dfff763d2c5de65f4a67374a..b9fd18d986464f317a9fb7ce709a9728ffb75751 100644
> --- a/net/sched/sch_taprio.c
> +++ b/net/sched/sch_taprio.c
> @@ -1641,6 +1641,10 @@ static void taprio_destroy(struct Qdisc *sch)
>  	list_del(&q->taprio_list);
>  	spin_unlock(&taprio_list_lock);
>  
> +	/* Note that taprio_reset() might not be called if an error
> +	 * happens in qdisc_create(), after taprio_init() has been called.
> +	 */
> +	hrtimer_cancel(&q->advance_timer);
>  
>  	taprio_disable_offload(dev, q, NULL);
>  
> -- 
> 2.33.0.800.g4c38ced690-goog
>