[Letux-kernel] [PATCH RFC] net: hso: register netdev later to avoid a race condition

H. Nikolaus Schaller hns at goldelico.com
Wed Apr 26 06:50:00 CEST 2017


Hi,

> Am 25.04.2017 um 23:11 schrieb Andreas Kemnade <andreas at kemnade.info>:
> 
> On Tue, 25 Apr 2017 15:29:53 +0200
> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
> 
>> 
>> So my conclusion is:
>> 
>> * dhcpd is recognising quite quickly that there is a new interface being enabled.
>> * and tries to do some ioctl which makes the kernel segfault
>> * and crashes dhcpd
>> 
>> The fix we are talking about makes this being ignored.
>> 
>> It might simply be that dhcpd is responding faster with an ioctl() than with older kernels.
>> So let's keep the patch for the moment.
>> 
> well, i would like to replace it with something upstreamable. But maybe
> it is best if you first send the 20ms-hack as a [PATCH RFC] together
> with the backtrace so that we have more brains on that topic.
> 
> How was dhcpcd started? Just so that I can properly reproduce that.

Just apt-get install isc-dhcp-client on Jessie.
This installs /etc/init.d/dhcpcd startup code and defaults.

No special rule(s) for hso.

root at letux:~# ps -ef|fgrep dhc
root      2653     1  0 00:01 ?        00:00:00 /sbin/dhcpcd
root      2689  2683  0 00:02 ttyO2    00:00:00 grep -F dhc
root at letux:~# ls -l /sbin/dhcpc*
lrwxrwxrwx 1 root root     24 Jan 18  2017 /sbin/dhcpcd -> /etc/alternatives/dhcpcd
-rwxr-xr-x 1 root root 108456 Nov 19  2014 /sbin/dhcpcd5
root at letux:~# ls -l /etc/alternatives/dhcpcd
lrwxrwxrwx 1 root root 13 Jan 18  2017 /etc/alternatives/dhcpcd -> /sbin/dhcpcd5
root at letux:~#

> 
> BTW: the other hso patch for the rmmod problem has already made it here:
> https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=a23f6ce6d95900ca83b44b6fa691afe6c7d4b941
> 
> Lets hope that during replicant testing no other additional hso problems
> uncover.
> 
> Regards,
> Andreas

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