Re: [dpdk-dev] [PATCH] doc: cryptodev deprecation notice for sym session changes

["Joseph, Anoob" <Anoob.Joseph@cavium.com>]

Hi Akhil, Konstantin,

Wouldn't the new element, userdata, conflict with the one referred by

rte_cryptodev_sym_session_set_user_data()
rte_cryptodev_sym_session_get_user_data()

Do you mind a name change for either? Or do you have a clear picture of when one should be used over the other?

Thanks,
Anoob

> -----Original Message-----
> From: Akhil Goyal <akhil.goyal@nxp.com>
> Sent: 12 November 2018 17:34
> To: Konstantin Ananyev <konstantin.ananyev@intel.com>; dev@dpdk.org; Ravi
> Kumar <ravi1.kumar@amd.com>; Jacob, Jerin
> <Jerin.JacobKollanukkaran@cavium.com>; Joseph, Anoob
> <Anoob.Joseph@cavium.com>; Declan Doherty <declan.doherty@intel.com>;
> Fiona Trahe <fiona.trahe@intel.com>; Tomasz Duszynski <tdu@semihalf.com>;
> Dmitri Epshtein <dima@marvell.com>; Natalie Samsonov
> <nsamsono@marvell.com>; Jay Zhou <jianjay.zhou@huawei.com>
> Subject: Re: [dpdk-dev] [PATCH] doc: cryptodev deprecation notice for sym
> session changes
> 
> External Email
> 
> On 10/11/2018 7:50 PM, Konstantin Ananyev wrote:
> > Below are details and reasoning for proposed changes.
> >
> > 1.rte_cryptodev_sym_session_init()/ rte_cryptodev_sym_session_clear()
> >    operate based on cytpodev device id, though inside
> >    rte_cryptodev_sym_session device specific data is addressed
> >    by driver id (not device id).
> >    That creates a problem with current implementation when we have
> >    two or more devices with the same driver used by the same session.
> >    Consider the following example:
> >
> >    struct rte_cryptodev_sym_session *sess;
> >    rte_cryptodev_sym_session_init(dev_id=X, sess, ...);
> >    rte_cryptodev_sym_session_init(dev_id=Y, sess, ...);
> >    rte_cryptodev_sym_session_clear(dev_id=X, sess);
> >
> >    After that point if X and Y uses the same driver,
> >    then sess can't be used by device Y any more.
> >    The reason for that - driver specific (not device specific)
> >    data per session, plus there is no information
> >    how many device instances use that data.
> >    Probably the simplest way to deal with that issue -
> >    add a reference counter per each driver data.
> >
> > 2.rte_cryptodev_sym_session_set_user_data() and
> >    rte_cryptodev_sym_session_get_user_data() -
> >    with current implementation there is no defined way for the user to
> >    determine what is the max allowed size of the private data.
> >    rte_cryptodev_sym_session_set_user_data() just blindly copies
> >    user provided data without checking memory boundaries violation.
> >    To overcome that issue propose to add 'uint16_t priv_size' into
> >    rte_cryptodev_sym_session structure.
> >
> > 3.rte_cryptodev_sym_session contains an array of variable size for
> >    driver specific data.
> >    Though number of elements in that array is determined by static
> >    variable nb_drivers, that could be modified by
> >    rte_cryptodev_allocate_driver().
> >    That construction seems to work ok so far, as right now users register
> >    all their PMDs at startup, though it doesn't mean that it would always
> >    remain like that.
> >    To make it less error prone propose to add 'uint16_t nb_drivers'
> >    into the rte_cryptodev_sym_session structure.
> >    At least that allows related functions to check that provided
> >    driver id wouldn't overrun variable array boundaries,
> >    again it allows to determine size of already allocated session
> >    without accessing global variable.
> >
> > 4.#2 and #3 above implies that now each struct rte_cryptodev_sym_session
> >    would have sort of readonly type data (init once at allocation time,
> >    keep unmodified through session life-time).
> >    That requires more changes in current cryptodev implementation:
> >    Right now inside cryptodev framework both rte_cryptodev_sym_session
> >    and driver specific session data are two completely different sctrucures
> >    (e.g. struct cryptodev_sym_session and struct null_crypto_session).
> >    Though current cryptodev implementation implicitly assumes that driver
> >    will allocate both of them from within the same mempool.
> >    Plus this is done in a manner that they override each other fields
> >    (reuse the same space - sort of implicit C union).
> >    That's probably not the best programming practice,
> >    plus make impossible to have readonly fields inside both of them.
> >    To overcome that situation propose to changed an API a bit, to allow
> >    to use two different mempools for these two distinct data structures.
> >
> >   5. Add 'uint64_t userdata' inside struct rte_cryptodev_sym_session.
> >     I suppose that self-explanatory, and might be used in a lot of places
> >     (would be quite useful for ipsec library we develop).
> >
> > The new proposed layout for rte_cryptodev_sym_session:
> > struct rte_cryptodev_sym_session {
> >          uint64_t userdata;
> >          /**< Can be used for external metadata */
> >          uint16_t nb_drivers;
> >          /**< number of elements in sess_data array */
> >          uint16_t priv_size;
> >          /**< session private data will be placed after sess_data */
> >          __extension__ struct {
> >                  void *data;
> >                  uint16_t refcnt;
> >          } sess_data[0];
> >          /**< Driver specific session material, variable size */ };
> >
> > Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> 
> Adding maintainers to ack this deprecation notice. These changes will impact all
> the PMDs and everyone should agree to these changes.
> 
> from NXP dpaa_sec, dpaa2_sec, caam_jr PMDs:
> 
> Acked-by: Akhil Goyal <akhil.goyal@nxp.com>
> > ---
> >   doc/guides/rel_notes/deprecation.rst | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> >
> > diff --git a/doc/guides/rel_notes/deprecation.rst
> > b/doc/guides/rel_notes/deprecation.rst
> > index d2aec64d1..998a0d92c 100644
> > --- a/doc/guides/rel_notes/deprecation.rst
> > +++ b/doc/guides/rel_notes/deprecation.rst
> > @@ -74,3 +74,12 @@ Deprecation Notices
> >
> >     This is due to a lack of flexibility and reliance on a type unusable with
> >     C++ programs (struct rte_flow_desc).
> > +
> > +* cryptodev: several API and ABI changes are planned for
> > +rte_cryptodev
> > +  in v19.02:
> > +
> > +  - The size and layout of ``rte_cryptodev_sym_session`` will change
> > +    to fix existing issues.
> > +  - The size and layout of ``rte_cryptodev_qp_conf`` and syntax of
> > +    ``rte_cryptodev_queue_pair_setup`` will change to to allow to use
> > +    two different mempools for crypto and device private sessions.