connector and netlink_broadcast (semop failed for cookie ...)

connector and netlink_broadcast (semop failed for cookie ...)

[Alexander Holler]

Hello,

I've recently enabled CONFIG_CONNECTOR in kernel 3.6.6 and now I've got 
the message "semop failed for cookie ..." when using cryptsetup (I've 
never got that error before).

A short search revealed the following discussion about ignoring errors 
from netlink_broadcast_filtered(): https://lkml.org/lkml/2011/8/19/60

connector doesn't use netlink_broadcast_filtered() directly but it 
returns netlink_broadcast() in cn_netlink_send() while 
netlink_broadcast() just is a wrapper around netlink_broadcast_filtered().

Could it be the case that cn_netlink_send() has to ignore the same 
return codes as done in kobject_uevent_env()? Or maybe the users of 
cn_netlink_send() have to ignore them?

Regards,

Alexander

Re: connector and netlink_broadcast (semop failed for cookie ...)

[Evgeniy Polyakov]

Hi

On Mon, Nov 05, 2012 at 08:42:32PM +0100, Alexander Holler (holler@ahsoftware.de) wrote:
> Could it be the case that cn_netlink_send() has to ignore the same
> return codes as done in kobject_uevent_env()? Or maybe the users of
> cn_netlink_send() have to ignore them?

We just do not know what to do with that error.
Pretty much it means nothing can be done about it.
There is no recovery path, no collection and resend, since it may lead to dos.

Its like knowing that udp packet get lost, but you do not have enough
buffer space to save it and block. Actually there is no buffer at all.
Kind of missed interrupt.

-- 
	Evgeniy Polyakov