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Message-ID: <97d1cc84-890c-3fcf-2efc-645633cd36b2@gmail.com>
Date:   Mon, 4 Apr 2022 17:22:00 -0700
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Subject: Re: [PATCH] Bluetooth: hci_qca: Use del_timer_sync() before freeing
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To:     Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        Ben Young Tae Kim <ytkim@qca.qualcomm.com>,
        Thomas Gleixner <tglx@linutronix.de>
References: <20220404182236.1caa174e@rorschach.local.home>
From:   Eric Dumazet <eric.dumazet@gmail.com>
In-Reply-To: <20220404182236.1caa174e@rorschach.local.home>
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On 4/4/22 15:22, Steven Rostedt wrote:
> [ Resending due to cut and paste failure of email address ]
>
> From: Steven Rostedt (Google) <rostedt@goodmis.org>
>
> While looking at a crash report on a timer list being corrupted, which
> usually happens when a timer is freed while still active. This is
> commonly triggered by code calling del_timer() instead of
> del_timer_sync() just before freeing.
>
> One possible culprit is the hci_qca driver, which does exactly that.
>
> Cc: stable@vger.kernel.org
> Fixes: 0ff252c1976da ("Bluetooth: hciuart: Add support QCA chipset for
> UART") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
> 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 ?


>   	qca->hu = NULL;
>