Subject: net: fix race in process_backlog
The recent NAPI rework (4fa57c9ea9f36f9ca852f3a88ca5d2f1aebbc960)
introduced a race between netif_rx() and process_backlog() which
resulted in softirq processing to drop dead.
netif_rx() process_backlog()
irq_disable();
skb = __skb_dequeue();
irq_enable();
irq_disable();
__skb_queue_tail();
napi_schedule();
irq_enable();
if (!skb)
napi_complete(); <-- oops!
we cleared the napi bit, even though there is data to process.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
net/core/dev.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6/net/core/dev.c
===================================================================
--- linux-2.6.orig/net/core/dev.c
+++ linux-2.6/net/core/dev.c
@@ -2095,11 +2095,11 @@ static int process_backlog(struct napi_s
local_irq_disable();
skb = __skb_dequeue(&queue->input_pkt_queue);
- local_irq_enable();
if (!skb) {
- napi_complete(napi);
+ __napi_complete(napi);
break;
}
+ local_irq_enable();
dev = skb->dev;
-
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