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Commit 57b22906 authored by Ross Lagerwall's avatar Ross Lagerwall Committed by David S. Miller
Browse files

xen/netback: Wake dealloc thread after completing zerocopy work 



Waking the dealloc thread before decrementing inflight_packets is racy
because it means the thread may go to sleep before inflight_packets is
decremented. If kthread_stop() has already been called, the dealloc
thread may wait forever with nothing to wake it. Instead, wake the
thread only after decrementing inflight_packets.

Signed-off-by: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a0a2a660

drivers/net/xen-netback/interface.c

+6 −0
Original line number Diff line number Diff line
@@ -61,6 +61,12 @@ void xenvif_skb_zerocopy_prepare(struct xenvif_queue *queue, 
void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue)

{

	atomic_dec(&queue->inflight_packets);



	/* Wake the dealloc thread _after_ decrementing inflight_packets so

	 * that if kthread_stop() has already been called, the dealloc thread

	 * does not wait forever with nothing to wake it.

	 */

	wake_up(&queue->dealloc_wq);

}



int xenvif_schedulable(struct xenvif *vif)

drivers/net/xen-netback/netback.c

+0 −1
Original line number Diff line number Diff line
@@ -1541,7 +1541,6 @@ void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success) 
		smp_wmb();

		queue->dealloc_prod++;

	} while (ubuf);

	wake_up(&queue->dealloc_wq);

	spin_unlock_irqrestore(&queue->callback_lock, flags);



	if (likely(zerocopy_success))