[ovs-discuss] n_actions in add_flow() and check_ofp_message_array()

Ben Pfaff blp at nicira.com
Tue Oct 18 13:26:29 UTC 2011

On Tue, Oct 18, 2011 at 04:23:03PM +0300, Ivan Zazulyak wrote:
> So, I am using a source code from a head of WDP branch and have a
> question regarding to the number of actions, stored in the
> wdp_flow_put::n_actions structure member.

It is a mistake to use the WDP branch.  It is hopelessly out-of-date.
The ideas in the WDP branch are implemented much better in "master", so
please upgrade to "master"

> This member is set in the add_flow() function and described in
> comments as number of actions in the flow.
> But in fact it is calculated by the check_ofp_message_array()
> function as a number of 8-byte blocks (slots).
> An action could occupy several slots, e.g currntly the
> ofp_action_dl_addr action structure requires 2 ones.
> Hereby are my conclusions:
> - n_action should be always treated as number of slots, not actual
> number of actions
> - application is responsible for parsing actions, based on the type
> of action and it's length
> Is it correct?

Yes, that's common practice in the OVS source tree.

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