From patchwork Mon Dec 10 21:55:51 2012
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Subject: ipgre rss is broken since gro
Date: Mon, 10 Dec 2012 11:55:51 -0000
From: Eric Dumazet <eric.dumazet@gmail.com>
X-Patchwork-Id: 205047
Message-Id: <1355176551.27891.57.camel@edumazet-glaptop>
To: Dmitry Kravkov <dmitry@broadcom.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>

On Mon, 2012-12-10 at 19:20 +0000, Dmitry Kravkov wrote:

> Yep, this resolved the issue - Interface is functional after 3 and 100 TCP connections. Thanks
>    
> 

I guess its only lowering probability of the race.

Could you try instead the following patch ?

I'll address the queue_mapping separately for net-next

Thanks

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diff --git a/include/net/gro_cells.h b/include/net/gro_cells.h
index 4fd8a4b..e5062c9 100644
--- a/include/net/gro_cells.h
+++ b/include/net/gro_cells.h
@@ -17,7 +17,6 @@ struct gro_cells {
 
 static inline void gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 {
-	unsigned long flags;
 	struct gro_cell *cell = gcells->cells;
 	struct net_device *dev = skb->dev;
 
@@ -35,32 +34,37 @@ static inline void gro_cells_receive(struct gro_cells *gcells, struct sk_buff *s
 		return;
 	}
 
-	spin_lock_irqsave(&cell->napi_skbs.lock, flags);
+	/* We run in BH context */
+	spin_lock(&cell->napi_skbs.lock);
 
 	__skb_queue_tail(&cell->napi_skbs, skb);
 	if (skb_queue_len(&cell->napi_skbs) == 1)
 		napi_schedule(&cell->napi);
 
-	spin_unlock_irqrestore(&cell->napi_skbs.lock, flags);
+	spin_unlock(&cell->napi_skbs.lock);
 }
 
+/* called unser BH context */
 static inline int gro_cell_poll(struct napi_struct *napi, int budget)
 {
 	struct gro_cell *cell = container_of(napi, struct gro_cell, napi);
 	struct sk_buff *skb;
 	int work_done = 0;
 
+	spin_lock(&cell->napi_skbs.lock);
 	while (work_done < budget) {
-		skb = skb_dequeue(&cell->napi_skbs);
+		skb = __skb_dequeue(&cell->napi_skbs);
 		if (!skb)
 			break;
-
+		spin_unlock(&cell->napi_skbs.lock);
 		napi_gro_receive(napi, skb);
 		work_done++;
+		spin_lock(&cell->napi_skbs.lock);
 	}
 
 	if (work_done < budget)
 		napi_complete(napi);
+	spin_unlock(&cell->napi_skbs.lock);
 	return work_done;
 }