net-rps: Fix brokeness causing OOO packets

Submitted by Eric Dumazet on Nov. 16, 2012, 7:04 p.m.

Details

Message ID 1353092655.10798.44.camel@edumazet-glaptop
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet Nov. 16, 2012, 7:04 p.m.
From: Tom Herbert <therbert@google.com>

In commit c445477d74ab3779 which adds aRFS to the kernel, the CPU
selected for RFS is not set correctly when CPU is changing.
This is causing OOO packets and probably other issues.

Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
---
 net/core/dev.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)



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Comments

David Miller Nov. 16, 2012, 7:36 p.m.
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 16 Nov 2012 11:04:15 -0800

> From: Tom Herbert <therbert@google.com>
> 
> In commit c445477d74ab3779 which adds aRFS to the kernel, the CPU
> selected for RFS is not set correctly when CPU is changing.
> This is causing OOO packets and probably other issues.
> 
> Signed-off-by: Tom Herbert <therbert@google.com>
> Acked-by: Eric Dumazet <edumazet@google.com>
> Acked-by: Ben Hutchings <bhutchings@solarflare.com>

Applied and queued up for -stable, thanks everyone.
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Patch hide | download patch | download mbox

diff --git a/net/core/dev.c b/net/core/dev.c
index bda6d00..c0946cb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2818,8 +2818,10 @@  static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
 		if (unlikely(tcpu != next_cpu) &&
 		    (tcpu == RPS_NO_CPU || !cpu_online(tcpu) ||
 		     ((int)(per_cpu(softnet_data, tcpu).input_queue_head -
-		      rflow->last_qtail)) >= 0))
+		      rflow->last_qtail)) >= 0)) {
+			tcpu = next_cpu;
 			rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
+		}
 
 		if (tcpu != RPS_NO_CPU && cpu_online(tcpu)) {
 			*rflowp = rflow;