Re: [PATCH net-next v2] openvswitch: reduce stack usage in do_execute_actions

[Eric Dumazet]

On Thu, Sep 21, 2023 at 9:42 PM Ilya Maximets <i.maximets@xxxxxxx> wrote:
>
> do_execute_actions() function can be called recursively multiple
> times while executing actions that require pipeline forking or
> recirculations.  It may also be re-entered multiple times if the packet
> leaves openvswitch module and re-enters it through a different port.
>
> Currently, there is a 256-byte array allocated on stack in this
> function that is supposed to hold NSH header.  Compilers tend to
> pre-allocate that space right at the beginning of the function:
>
>      a88:       48 81 ec b0 01 00 00    sub    $0x1b0,%rsp
>
> NSH is not a very common protocol, but the space is allocated on every
> recursive call or re-entry multiplying the wasted stack space.
>

Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>