From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: [PATCHv1 net] xen-netback: stop the guest rx thread after a fatal error Date: Mon, 2 Feb 2015 16:57:51 +0000 Message-ID: <1422896271-26551-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain Cc: David Vrabel , , Ian Campbell , Wei Liu To: Return-path: Received: from smtp.citrix.com ([66.165.176.89]:29250 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932536AbbBBQ6D (ORCPT ); Mon, 2 Feb 2015 11:58:03 -0500 Sender: netdev-owner@vger.kernel.org List-ID: After commit e9d8b2c2968499c1f96563e6522c56958d5a1d0d (xen-netback: disable rogue vif in kthread context), a fatal (protocol) error would leave the guest Rx thread spinning, wasting CPU time. Commit ecf08d2dbb96d5a4b4bcc53a39e8d29cc8fef02e (xen-netback: reintroduce guest Rx stall detection) made this even worse by removing a cond_resched() from this path. Since a fatal error is non-recoverable, just allow the guest Rx thread to exit. This requires taking additional refs to the task so the thread exiting early is handled safely. Signed-off-by: David Vrabel Reported-by: Julien Grall Tested-by: Julien Grall --- drivers/net/xen-netback/interface.c | 2 ++ drivers/net/xen-netback/netback.c | 3 +-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 9259a73..037f74f 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -578,6 +578,7 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref, goto err_rx_unbind; } queue->task = task; + get_task_struct(task); task = kthread_create(xenvif_dealloc_kthread, (void *)queue, "%s-dealloc", queue->name); @@ -634,6 +635,7 @@ void xenvif_disconnect(struct xenvif *vif) if (queue->task) { kthread_stop(queue->task); + put_task_struct(queue->task); queue->task = NULL; } diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 908e65e..c8ce701 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -2109,8 +2109,7 @@ int xenvif_kthread_guest_rx(void *data) */ if (unlikely(vif->disabled && queue->id == 0)) { xenvif_carrier_off(vif); - xenvif_rx_queue_purge(queue); - continue; + break; } if (!skb_queue_empty(&queue->rx_queue)) -- 1.7.10.4