netdev - RE: [PATCH] [NET]: Fix Ooops of napi net_rx

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Date:	Tue, 11 Dec 2007 16:38:37 -0800
From:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
To:	"Joonwoo Park" <joonwpark81@...il.com>
Cc:	"David Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <herbert@...dor.apana.org.au>,
	"Kok, Auke-jan H" <auke-jan.h.kok@...el.com>
Subject: RE: [PATCH] [NET]: Fix Ooops of napi net_rx_action.

Joonwoo Park wrote:
> 2007/12/12, Brandeburg, Jesse <jesse.brandeburg@...el.com>:
>> 
>> all drivers using NAPI in 2.6.24+ (NNAPI??) must return zero here,
>> after calling netif_rx_complete.  netif_rx_complete plus work_done
>> != 0 causes a bug. 
>> 
> 
> Brandeburg,
> Don't we need to return non-zero work_done after netif_rx_complete if
> work_done != weight?

Actually we just need to make sure we don't return work_done == weight
as it is checked on line 2210 of dev.c.
I should also note that I was wrong above, and that the requirement is
that we MUST not return work_done == weight when indicating
netif_rx_complete.

So, returning 0 when we actually did some work, but are being removed
from the poll list because something like !netif_running, is probably
okay, but I'm sure someone will disagree with me.  Maybe returning like
this would be better
diff --git a/drivers/net/e1000/e1000_main.c
b/drivers/net/e1000/e1000_main.c
index 724f067..76d5e3b 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3933,6 +3933,10 @@ quit_polling:
                        e1000_set_itr(adapter);
                netif_rx_complete(poll_dev, napi);
                e1000_irq_enable(adapter);
+               if (work_done == weight)
+                       return work_done - 1;
+               else
+                       return work_done;
        }

        return work_done;

Jesse

 
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