From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: jgross@suse.com, xen-devel@lists.xenproject.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
vineethp@amazon.com, wei.liu2@citrix.com,
paul.durrant@citrix.com, stable@vger.kernel.org
Subject: Re: [PATCH] xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend()
Date: Mon, 30 Jan 2017 13:23:27 -0500 [thread overview]
Message-ID: <40057d9d-c615-1a2b-63a2-ab717c29d659@oracle.com> (raw)
In-Reply-To: <1485799651.6360.101.camel@edumazet-glaptop3.roam.corp.google.com>
On 01/30/2017 01:07 PM, Eric Dumazet wrote:
> On Mon, 2017-01-30 at 12:45 -0500, Boris Ostrovsky wrote:
>> rx_refill_timer should be deleted as soon as we disconnect from the
>> backend since otherwise it is possible for the timer to go off before
>> we get to xennet_destroy_queues(). If this happens we may dereference
>> queue->rx.sring which is set to NULL in xennet_disconnect_backend().
>>
>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>> CC: stable@vger.kernel.org
>> ---
>> drivers/net/xen-netfront.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
>> index 8315fe7..722fe9f 100644
>> --- a/drivers/net/xen-netfront.c
>> +++ b/drivers/net/xen-netfront.c
>> @@ -1379,6 +1379,8 @@ static void xennet_disconnect_backend(struct netfront_info *info)
>> for (i = 0; i < num_queues && info->queues; ++i) {
>> struct netfront_queue *queue = &info->queues[i];
>>
>> + del_timer_sync(&queue->rx_refill_timer);
>> +
> If napi_disable() was not called before this del_timer_sync(), another
> RX might come here and rearm rx_refill_timer.
We do netif_carrier_off() first thing in xennet_disconnect_backend() and
the only place where the timer is rearmed is xennet_alloc_rx_buffers(),
which is guarded by netif_carrier_ok() check.
-boris
>
>> if (queue->tx_irq && (queue->tx_irq == queue->rx_irq))
>> unbind_from_irqhandler(queue->tx_irq, queue);
>> if (queue->tx_irq && (queue->tx_irq != queue->rx_irq)) {
>> @@ -1733,7 +1735,6 @@ static void xennet_destroy_queues(struct netfront_info *info)
>>
>> if (netif_running(info->netdev))
>> napi_disable(&queue->napi);
>> - del_timer_sync(&queue->rx_refill_timer);
>> netif_napi_del(&queue->napi);
>> }
>>
>
next prev parent reply other threads:[~2017-01-30 18:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-30 17:45 [PATCH] xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend() Boris Ostrovsky
2017-01-30 18:07 ` Eric Dumazet
2017-01-30 18:23 ` Boris Ostrovsky [this message]
2017-01-30 19:06 ` Eric Dumazet
2017-01-30 19:31 ` Boris Ostrovsky
2017-01-31 17:47 ` Boris Ostrovsky
2017-02-01 23:29 ` Boris Ostrovsky
2017-02-02 0:01 ` Eric Dumazet
2017-02-03 9:38 ` Juergen Gross
2017-02-09 13:42 ` Boris Ostrovsky
2017-02-10 18:46 ` David Miller
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