On Fri, Aug 29, 2014 at 12:53 PM, Sabrina Dubroca [off-list ref] wrote:

2014-08-29, 11:14:48 -0700, Cong Wang wrote:

quoted

On Fri, Aug 29, 2014 at 8:26 AM, Tommi Rantala [off-list ref] wrote:

quoted

[   77.297196] RTNL: assertion failed at net/ipv6/addrconf.c (1699)
[   77.298080] CPU: 0 PID: 4842 Comm: trinity-main Not tainted 3.17.0-rc2+ #30
[   77.299039] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   77.299789]  ffff88003d76a618 ffff880026133c50 ffffffff8238ba79
ffff880037c84520
[   77.300829]  ffff880026133c90 ffffffff820bd52b 0000000000000000
ffffffff82d86c40
[   77.301869]  0000000000000000 00000000f76fd1e1 ffff8800382d8000
ffff8800382d8220
[   77.302906] Call Trace:
[   77.303246]  [<ffffffff8238ba79>] dump_stack+0x4d/0x66
[   77.303928]  [<ffffffff820bd52b>] addrconf_join_solict+0x4b/0xb0
[   77.304731]  [<ffffffff820b031b>] ipv6_dev_ac_inc+0x2bb/0x330
[   77.305498]  [<ffffffff820b0060>] ? ac6_seq_start+0x260/0x260
[   77.306257]  [<ffffffff820b05fe>] ipv6_sock_ac_join+0x26e/0x360
[   77.307046]  [<ffffffff820b0429>] ? ipv6_sock_ac_join+0x99/0x360
[   77.307798]  [<ffffffff820cdd60>] do_ipv6_setsockopt.isra.5+0xa70/0xf20

I think we should just use rtnl_lock() instead of rcu_read_lock() there,
it is not a hot path worth optimization.

Please try the attached patch.

note: it doesn't build as it is now, it needs:

-EXPORT_SYMBOL(dev_get_by_flags_rcu);
+EXPORT_SYMBOL(dev_get_by_flags);


I just tried your patch with a basic test program (open
socket/join/leave/close and open socket/join/close).

I think you need to modify ipv6_sock_ac_close as well, or you can still
trigger the assertion when closing the socket without leaving first.

You are absolutely right here.

Can I have your Signed-off-by and Tested-by before sending the patch
formally?

Thanks!