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authorRoss Lagerwall <ross.lagerwall@citrix.com>2015-08-04 15:40:59 +0100
committerDavid S. Miller <davem@davemloft.net>2015-08-06 23:42:48 -0700
commit57b229063ae6dc65036209018dc7f4290cc026bb (patch)
treea465b6e776bef923f818d6601c96516c452d85fe
parenta0a2a6602496a45ae838a96db8b8173794b5d398 (diff)
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: Ross Lagerwall <ross.lagerwall@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/xen-netback/interface.c6
-rw-r--r--drivers/net/xen-netback/netback.c1
2 files changed, 6 insertions, 1 deletions
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 1a83e190fc15..28577a31549d 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -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)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 1b406e706a01..3f44b522b831 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -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))

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