Re: [PATCH 1/3] netlink: fix NETLINK_RECV_NO_ENOBUFS in netlink_set_err()

[Patrick McHardy <kaber@trash.net>]

Pablo Neira Ayuso wrote:
> Patrick McHardy wrote:
>> Pablo Neira Ayuso wrote:
>>> Currently, ENOBUFS errors are reported to the socket via
>>> netlink_set_err() even if NETLINK_RECV_NO_ENOBUFS is set. However,
>>> that should not happen. This fixes this problem and it changes the
>>> prototype of netlink_set_err() to return the number of sockets whose
>>> error has been set. This allows to know if any error has been set.
>>> This return value is used in the next patch in these bugfix series.
>> But that only happens if we have a message allocate error, which is
>> a different situation than rcvqueue overrun, which I thought the
>> original patch was supposed to handle (disable netlink congestion
>> control).
> 
> Yes, allocation is a different situation but we still report ENOBUFS to
> user-space. I think that NETLINK_RECV_NO_ENOBUFS is there to a) disable
> ENOBUFS reports to user-space and b) disable Netlink congestion.
> 
>> Is there any problem with these errors?
> 
> Specifically in ctnetlink, if we fail to allocate a message in ctnetlink
> and NETLINK_RECV_NO_ENOBUFS is set, we still lose an event and that
> should not happen.

I assume you mean "not set"? Otherwise I fail to follow :)