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

Ingo Molnar
2009-03-24T15:47:50Z

* Ingo Molnar <mingo@elte.hu> wrote:

>
> * Herbert Xu <herbert@gondor.apana.org.au> 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