Re: [dpdk-dev] [PATCH v2 1/2] examples/ipsec-secgw: fix 1st pkt dropped for inline crypto

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Akhil,

> >
> >>>> Subject: Re: [dpdk-dev] [PATCH v2 1/2] examples/ipsec-secgw: fix 1st
> >>>> pkt dropped for inline crypto
> >>>>
> >>>> Hi Bernard,
> >>>>
> >>>> On 3/7/2019 8:27 PM, Bernard Iremonger wrote:
> >>>>> Inline crypto installs a flow rule in the NIC. This flow rule must
> >>>>> be installed before the first inbound packet is received.
> >>>>>
> >>>>> The create_session() function installs the flow rule,
> >>>>> create_session() has been refactored into create_inline_session()
> >>>>> and create_lookaside_session(). The create_inline_session() function
> >>>>> uses the socket_ctx data and is now called at initialisation in
> >>>>> sa_add_rules().
> >>>> why do we need a separate function for session creation for inline
> >>>> and lookaside cases?
> >>>> Why can't we initialize the sessions on sa_init in both the cases?
> >>> For the create_inline_session(struct socket_ctx *skt_ctx, struct
> >>> ipsec_sa *sa) function, all of the required data is available in the in the
> >> skt_ctx variable.
> >>> The skt_ctx variable is already setup when sa_init() is called.
> >>>
> >>> For the create_lookaside_session(struct ipsec_ctx *ipsec_ctx, struct
> >>> ipsec_sa *sa) function, the required data is available in the ipsec_ctx
> >> variable.
> >>> The ipsec_ctx variable is not setup when sa_init() is called.
> >>> It is setup in the main_loop() function  when the variable qconf is setup.
> >>> The main_loop() function is called after the sa_init() function is called.
> >>>
> >>> I hope this  answers your question
> >> Whatever information that is required for session creation is available before
> >> we call the main loop() in both the cases.
> >> My point is both the sessions(inline/lookaside) can be init at the same
> >> position, we do not need to have a separate path for them.
> >> If it is not possible in sa_init(), it may be somewhere else before the actual
> >> data path is started.
> >>
> >> The problem with inline processing is that, h/w need to know the SA before
> >> the first packet is received. So we cannot init the session on receive of first
> >> packet. However there is no such limitation in case of lookaside, it can be
> >> initialized anywhere.
> >>
> >> -Akhil
> > This patch is intended to fix the bug in the inline processing, which is that  the flow rule must be installed, before the first packet is
> received while leaving the lookaside processing as it was originally.
> >
> > It is not intended to refactor the lookaside processing.
> The fix provided should not make the code complex and difficult to
> understand when we have the option available to fix that in a simpler
> way. Application is already complex enough(4 action types) and by adding
> separate code for session init at two different places will be difficult
> to maintain in future and will reduce the code readability.

It can be changed to do initialization for both security and crypto sessions at sa_init()
time, but it would cause much more changes in the code:
the idea is for each SA go through all available crypto-devices, check their capabilities,
and if they match, we'll invoke init_session() for that SA and device.
That way at the end of sa_init() we'll have crypto-sessions that can be used on any attached
crypto-dev.
As a drawback -  each session might occupy more memory.
Though as I said, it would require more changes (and testing) in init code.
So my thought to have this patch as it is and then add these changes as a separate patch series (phase 2).
What do you think?
Konstantin