[ovs-dev] [PATCH v4 10/12] ofproto: Postpone sending flow removed messages.

[Jarno Rajahalme]

> On Jun 10, 2015, at 5:43 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> On Tue, Jun 09, 2015 at 05:24:17PM -0700, Jarno Rajahalme wrote:
>> The final flow stats are available only after there are no references
>> to the rule.  Postpone sending the flow removed message until the
>> final stats are available.
>> 
>> Signed-off-by: Jarno Rajahalme <jrajahalme at nicira.com>
> 
> I'm a little nervous about doing so much work from a postpone callback.
> This is probably because I tend to think of them in a kernel context,
> where RCU callbacks run from (if I recall correctly) a softirq, where it
> isn't safe to do much work.  But I don't have a real reason to cite why
> we shouldn't do this (except that we only have one ovsrcu thread, so
> that we should avoid doing much work in it).  Do you feel comfortable
> with it?

An alternative would be to queue the message sending via RCU callbacks for the main thread to do by itself later. Want me to try that out?

  Jarno