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xen/netback: Wake dealloc thread after completing zerocopy work

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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: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ross Lagerwall 2015-08-04 15:40:59 +01:00 committed by David S. Miller
parent a0a2a66024
commit 57b229063a
2 changed files with 6 additions and 1 deletions
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6
drivers/net/xen-netback/interface.c
View File

@ -61,6 +61,12 @@ void xenvif_skb_zerocopy_prepare(struct xenvif_queue *queue,
void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue) void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue)
{ {
atomic_dec(&queue->inflight_packets); 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) int xenvif_schedulable(struct xenvif *vif)

1
drivers/net/xen-netback/netback.c
View File

@ -1541,7 +1541,6 @@ void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
smp_wmb(); smp_wmb();
queue->dealloc_prod++; queue->dealloc_prod++;
} while (ubuf); } while (ubuf);
wake_up(&queue->dealloc_wq);
spin_unlock_irqrestore(&queue->callback_lock, flags); spin_unlock_irqrestore(&queue->callback_lock, flags);
if (likely(zerocopy_success)) if (likely(zerocopy_success))