Re: Revert "gro: Fix legacy path napi_complete crash", (was: Re:Linux 2.6.29)

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> 
> * Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
> 
> > On Tue, Mar 24, 2009 at 03:39:42PM +0100, Ingo Molnar wrote:
> > >
> > > Subject: [PATCH] net: Fix netpoll lockup in legacy receive path
> > 
> > Actually, this patch is still racy.  If some interrupt comes in
> > and we suddenly get the maximum amount of backlog we can still
> > hang when we call __napi_complete incorrectly.  It's unlikely
> > but we certainly shouldn't allow that.  Here's a better version.
> > 
> > net: Fix netpoll lockup in legacy receive path
> 
> ok - i'm testing with this now.

test failure on one of the boxes, interface got stuck after ~100K 
packets:

eth1      Link encap:Ethernet  HWaddr 00:13:D4:DC:41:12  
          inet addr:10.0.1.13  Bcast:10.0.1.255  Mask:255.255.255.0
          inet6 addr: fe80::213:d4ff:fedc:4112/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:22555 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1897 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2435071 (2.3 MiB)  TX bytes:503790 (491.9 KiB)
          Interrupt:11 Base address:0x4000 

i'm going back to your previous version for now - it might still be 
racy but it worked well for about 1.5 hours of test-time.

	Ingo
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