linux-kernel - Re: [PATCH] Bluetooth: hci_qca: Use del_timer

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Message-ID: <20220404210746.32bb4df6@rorschach.local.home>
Date:   Mon, 4 Apr 2022 21:07:46 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Ben Young Tae Kim <ytkim@....qualcomm.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] Bluetooth: hci_qca: Use del_timer_sync() before freeing

On Mon, 4 Apr 2022 17:22:00 -0700
Eric Dumazet <eric.dumazet@...il.com> wrote:
> > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> > index f6e91fb432a3..73a8c72b5aae 100644
> > --- a/drivers/bluetooth/hci_qca.c
> > +++ b/drivers/bluetooth/hci_qca.c
> > @@ -696,8 +696,8 @@ static int qca_close(struct hci_uart *hu)
> >   	skb_queue_purge(&qca->tx_wait_q);
> >   	skb_queue_purge(&qca->txq);
> >   	skb_queue_purge(&qca->rx_memdump_q);
> > -	del_timer(&qca->tx_idle_timer);
> > -	del_timer(&qca->wake_retrans_timer);
> > +	del_timer_sync(&qca->tx_idle_timer);
> > +	del_timer_sync(&qca->wake_retrans_timer);  
> 
> 
> It seems the wake_retrans_timer could be re-armed from a work queue.
> 
> So perhaps we need to make sure qca->workqueue is destroyed
> 
> before these del_timer_sync() calls ?
> 
> >   	destroy_workqueue(qca->workqueue);  
> 
> 
> ie move this destroy_workqueue() up ?

Yeah, that could be a problem. I would think moving it up would help,
if that's what requeue's the timers.

-- Steve


> 
> 
> >   	qca->hu = NULL;
> >