Re: [dpdk-dev] [v2 1/2] cryptodev: support enqueue callback functions

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

> > > > >
> > > > > In an eventdev world, multiple workers (with ordered queue) will
> > > > > be working on IPsec ESP processing. The ESP header's sequence
> > > > > number is unique and has to be sequentially incremented in an orderly
> > manner.
> > > > > This rises a need for incrementing sequence number in crypto stage
> > > > > especially in event crypto adapter. By adding a user callback to
> > > > > cryptodev at enqueue burst, the user callback will get executed in
> > > > > the context of event crypto adapter. This helps the application to
> > > > > increment the ESP sequence number atomically and orderly manner.
> > > > >
> > > > > This patch adds APIs to add/remove callback functions. The
> > > > > callback function will be called for each burst of crypto ops
> > > > > received on a given crypto device queue pair.
> > > > >
> > > > > v1->v2:
> > > > > Moved callback related members to the end of cryptodev struct
> > > > > Added support for RCU
> > > > >
> > > > > Signed-off-by: Abhinandan Gujjar <abhinandan.gujjar@intel.com>
> > > > > ---
> > > > >  config/common_base                             |   1 +
> > > > >  lib/librte_cryptodev/Makefile                  |   2 +-
> > > > >  lib/librte_cryptodev/rte_cryptodev.c           | 157
> > > > +++++++++++++++++++++++++
> > > > >  lib/librte_cryptodev/rte_cryptodev.h           | 154
> > > > +++++++++++++++++++++++-
> > > > >  lib/librte_cryptodev/rte_cryptodev_version.map |   6 +
> > > > >  5 files changed, 318 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/config/common_base b/config/common_base index
> > > > > fbf0ee7..f5ebde4 100644
> > > > > --- a/config/common_base
> > > > > +++ b/config/common_base
> > > > > @@ -599,6 +599,7 @@
> > > > CONFIG_RTE_LIBRTE_PMD_BBDEV_FPGA_5GNR_FEC=y
> > > > >  #
> > > > >  CONFIG_RTE_LIBRTE_CRYPTODEV=y
> > > > >  CONFIG_RTE_CRYPTO_MAX_DEVS=64
> > > > > +CONFIG_RTE_CRYPTODEV_CALLBACKS=y
> > > > >
> > > > >  #
> > > > >  # Compile PMD for ARMv8 Crypto device diff --git
> > > > > a/lib/librte_cryptodev/Makefile b/lib/librte_cryptodev/Makefile
> > > > > index
> > > > > 73e77a2..514d552 100644
> > > > > --- a/lib/librte_cryptodev/Makefile
> > > > > +++ b/lib/librte_cryptodev/Makefile
> > > > > @@ -10,7 +10,7 @@ LIB = librte_cryptodev.a  CFLAGS += -O3  CFLAGS
> > > > > +=
> > > > > $(WERROR_FLAGS)  LDLIBS += -lrte_eal -lrte_mempool -lrte_ring
> > > > > -lrte_mbuf -LDLIBS += -lrte_kvargs
> > > > > +LDLIBS += -lrte_kvargs -lrte_rcu
> > > > >
> > > > >  # library source files
> > > > >  SRCS-y += rte_cryptodev.c rte_cryptodev_pmd.c
> > > > > cryptodev_trace_points.c diff --git
> > > > > a/lib/librte_cryptodev/rte_cryptodev.c
> > > > > b/lib/librte_cryptodev/rte_cryptodev.c
> > > > > index 1dd795b..2fb3e35 100644
> > > > > --- a/lib/librte_cryptodev/rte_cryptodev.c
> > > > > +++ b/lib/librte_cryptodev/rte_cryptodev.c
> > > > > @@ -38,6 +38,7 @@
> > > > >  #include <rte_string_fns.h>
> > > > >  #include <rte_compat.h>
> > > > >  #include <rte_function_versioning.h>
> > > > > +#include <rte_rcu_qsbr.h>
> > > > >
> > > > >  #include "rte_crypto.h"
> > > > >  #include "rte_cryptodev.h"
> > > > > @@ -499,6 +500,10 @@ struct
> > > > rte_cryptodev_sym_session_pool_private_data {
> > > > >  	return 0;
> > > > >  }
> > > > >
> > > > > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > > > > +/* spinlock for crypto device enq callbacks */ static
> > > > > +rte_spinlock_t rte_cryptodev_enq_cb_lock =
> > > > > +RTE_SPINLOCK_INITIALIZER; #endif
> > > > >
> > > > >  const char *
> > > > >  rte_cryptodev_get_feature_name(uint64_t flag) @@ -1449,6
> > > > > +1454,158
> > > > @@
> > > > > struct rte_cryptodev *
> > > > >  	rte_spinlock_unlock(&rte_cryptodev_cb_lock);
> > > > >  }
> > > > >
> > > > > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > > > > +int
> > > > > +rte_cryptodev_rcu_qsbr_add(uint8_t dev_id, struct rte_rcu_qsbr
> > > > > +*qsbr) {
> > > > > +
> > > > > +	struct rte_cryptodev *dev;
> > > > > +
> > > > > +	if (!rte_cryptodev_pmd_is_valid_dev(dev_id)) {
> > > > > +		CDEV_LOG_ERR("Invalid dev_id=%" PRIu8, dev_id);
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	dev = &rte_crypto_devices[dev_id];
> > > > > +	dev->qsbr = qsbr;
> > > > > +	return 0;
> > > > > +}
> > > >
> > > > So if I understand your patch correctly you propose a new working
> > > > model for
> > > > crypto-devs:
> > > > 1. Control-plane has to allocate/setup rcu_qsbr and do
> > > > rte_cryptodev_rcu_qsbr_add().
> > > > 2. Data-plane has somehow to obtain pointer to that rcu_qsbr and
> > > > wrap
> > > > cryptodev_enqueue()
> > > >    with rcu_qsbr_quiescent()  or rcu_qsbr_online()/rcu_qsbr_offline().
> > > Yes. I think, it is not a new model. It is same as RCU integration with LPM.
> > > Please refer: https://patches.dpdk.org/cover/73673/
> >
> > I am talking about new working model for crypto-dev enqueue/dequeue.
> > As I said above now it becomes data-plane thread responsibility to:
> >  -somehow to obtain pointer to that rcu_qsbr for each cryptodev it is using.
> >  -call rcu sync functions (quiescent/online/offline) on a regular basis.
> It is not on regular basis. When data plane comes up, they report online.
> They report quiescent when they are done with critical section or shared structure.

I understand that, but it means all existing apps have to be changed that way.

> All though, there is some dataplane changes involved here, I don't think, it is major.

I still think our goal here should be to make no visible changes to the dataplane.
I.E. all necessary data-plane changes need to be hidden inside CB invocation part.  

> 
> > Note that now data-plane thread would have to do that always - even if
> > there are now callbacks installed for that cryptodev queue right now.
> > All that changes behaviour of existing apps and I presume would reduce
> > adoption of  that fature.
> There is always trade off involved!
> In the previous patch, you suggested that some lazy app may not free up the
> memory allocated by add cb. For such apps, this patch has sync mechanism
> with some additional cost of CP & DP changes.

Sigh, it is not about laziness of the app.
The problem with current ethedev cb mechanism and yours V1 (which was just a clone of it) -
CP doesn't know when it is safe after CB removal to free related memory.

> > I still think all this callback mechanism should be totally opaque to data-plane
> > threads - user shouldn't change his app code depending on would some
> > enqueue/dequeue callbacks be installed or not.
> I am not sure, how that can be implemented with existing RCU design.

As I said below the simplest way - with calling rcu onine/offline inside CB invocation block.
That's why I asked you - did you try that approach and what is the perf numbers?
I presume with no callbacks installed the perf change should be nearly zero.

> @Honnappa Nagarahalli, Do you have any suggestions?
> 
> >
> > >
> > > >
> > > > That seems quite a big change and I don't think it is acceptable for
> > > > most users.
> > > > From my perspective adding/installing call-backs to the dev has to
> > > > be opaque to the data-plane code.
> > > > Also note that different callbacks can be installed by different
> > > > entities (libs) and might have no idea about each other.
> > > > That's why I thought it would be better to make all this RCU stuff
> > > > internal inside cryptodev:
> > > >     hide all this rcu_qsbr allocation/setup inside cryptod somehow to
> > obtain pointer to that rcu_qsbr ev init/queue setup
> > > >     invoke rcu_qsbr_online()/rcu_qsbr_offline() inside
> > cryptodev_enqueue().
> > > I have already tried exploring above stuffs. There are too many constraints.
> > > The changes don't fit in, as per RCU design.
> >
> > Hmm could you be more specific here - what constraints are you referring
> > to?
> >
> > > Moreover, having rcu api under enqueue_burst() will affect the
> > performance.
> >
> > It most likely will. Though my expectation it will affect performance only
> > when some callbacks are installed. My thought here:
> > callback function by itself will affect cryptdev_enqueue performance
> > anyway,
> With existing callback design, I have measured the performance(with crypto perf test) on xeon.
> It was almost negligible and same was shared with Declan.

I am asking about different thing: did you try alternate approach I described,
that wouldn't require changes in the user data-plane code.

> That is one of the reasons, I didn't want to add to many stuffs in to the callback.
> The best part of existing design is crypto lib is not much modified.
> The changes are either pushed to CP or DP.
> 
> so adding extra overhead for sync is probably ok here.

I think that extra overhead when callbacks are present is expected and
probably acceptable.
Changes in the upper-layer data-plane code - probably not.

> > Though for situation when no callbacks are installed - perfomance should be
> > left unaffected (or impact should be as small as possible).
> >
> > > The changes are more on control plane side, which is one time.
> > > The data plane changes are minimal.
> >
> > I still think upper layer data-plane code should stay unaffected (zero
> > changes).
> >
> > > >
> > > > > +
> > > > > +struct rte_cryptodev_enq_callback *
> > > > > +rte_cryptodev_add_enq_callback(uint8_t dev_id,
> > > > > +			       uint16_t qp_id,
> > > > > +			       rte_cryptodev_enq_cb_fn cb_fn,
> > > > > +			       void *cb_arg)
> > > > > +{
> > > > > +	struct rte_cryptodev *dev;
> > > > > +	struct rte_cryptodev_enq_callback *cb, *tail;
> > > > > +
> > > > > +	if (!cb_fn)
> > > > > +		return NULL;
> > > > > +
> > > > > +	if (!rte_cryptodev_pmd_is_valid_dev(dev_id)) {
> > > > > +		CDEV_LOG_ERR("Invalid dev_id=%" PRIu8, dev_id);
> > > > > +		return NULL;
> > > > > +	}
> > > > > +
> > > > > +	dev = &rte_crypto_devices[dev_id];
> > > > > +	if (qp_id >= dev->data->nb_queue_pairs) {
> > > > > +		CDEV_LOG_ERR("Invalid queue_pair_id=%d", qp_id);
> > > > > +		return NULL;
> > > > > +	}
> > > > > +
> > > > > +	cb = rte_zmalloc(NULL, sizeof(*cb), 0);
> > > > > +	if (cb == NULL) {
> > > > > +		CDEV_LOG_ERR("Failed to allocate memory for callback on "
> > > > > +			     "dev=%d, queue_pair_id=%d", dev_id, qp_id);
> > > > > +		rte_errno = ENOMEM;
> > > > > +		return NULL;
> > > > > +	}
> > > > > +
> > > > > +	cb->fn = cb_fn;
> > > > > +	cb->arg = cb_arg;
> > > > > +
> > > > > +	rte_spinlock_lock(&rte_cryptodev_enq_cb_lock);
> > > > > +	if (dev->enq_cbs == NULL) {
> > > > > +		dev->enq_cbs = rte_zmalloc(NULL, sizeof(cb) *
> > > > > +					   dev->data->nb_queue_pairs, 0);
> > > > > +		if (dev->enq_cbs == NULL) {
> > > > > +			CDEV_LOG_ERR("Failed to allocate memory for
> > > > callbacks");
> > > > > +			rte_errno = ENOMEM;
> > > > > +			rte_free(cb);
> > > > > +			return NULL;
> > > > > +		}
> > > > > +	}
> > > > > +
> > > > > +	/* Add the callbacks in fifo order. */
> > > > > +	tail = dev->enq_cbs[qp_id];
> > > > > +	if (tail) {
> > > > > +		while (tail->next)
> > > > > +			tail = tail->next;
> > > > > +		tail->next = cb;
> > > > > +	} else
> > > > > +		dev->enq_cbs[qp_id] = cb;
> > > > > +
> > > > > +	rte_spinlock_unlock(&rte_cryptodev_enq_cb_lock);
> > > > > +
> > > > > +	return cb;
> > > > > +}
> > > > > +
> > > > > +int
> > > > > +rte_cryptodev_remove_enq_callback(uint8_t dev_id,
> > > > > +				  uint16_t qp_id,
> > > > > +				  struct rte_cryptodev_enq_callback *cb) {
> > > > > +	struct rte_cryptodev *dev;
> > > > > +	struct rte_cryptodev_enq_callback **prev_cb, *curr_cb;
> > > > > +	uint16_t qp;
> > > > > +	int free_mem;
> > > > > +	int ret;
> > > > > +
> > > > > +	free_mem = 1;
> > > > > +
> > > > > +	if (!cb) {
> > > > > +		CDEV_LOG_ERR("cb is NULL");
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	if (!rte_cryptodev_pmd_is_valid_dev(dev_id)) {
> > > > > +		CDEV_LOG_ERR("Invalid dev_id=%" PRIu8, dev_id);
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	dev = &rte_crypto_devices[dev_id];
> > > > > +	if (qp_id >= dev->data->nb_queue_pairs) {
> > > > > +		CDEV_LOG_ERR("Invalid queue_pair_id=%d", qp_id);
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	if (!dev->qsbr) {
> > > > > +		CDEV_LOG_ERR("Rcu qsbr is NULL");
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	rte_spinlock_lock(&rte_cryptodev_enq_cb_lock);
> > > > > +	if (dev->enq_cbs == NULL) {
> > > > > +		rte_spinlock_unlock(&rte_cryptodev_enq_cb_lock);
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	prev_cb = &dev->enq_cbs[qp_id];
> > > > > +	for (; *prev_cb != NULL; prev_cb = &curr_cb->next) {
> > > > > +		curr_cb = *prev_cb;
> > > > > +		if (curr_cb == cb) {
> > > > > +			/* Remove the user cb from the callback list. */
> > > > > +			*prev_cb = curr_cb->next;
> > > > > +			ret = 0;
> > > > > +			break;
> > > > > +		}
> > > > > +	}
> > > > > +
> > > > > +	if (!ret) {
> > > > > +		/* Call sync with invalid thread id as this is part of
> > > > > +		 * control plane API */
> > > > > +		rte_rcu_qsbr_synchronize(dev->qsbr,
> > > > > +					 RTE_QSBR_THRID_INVALID);
> > > > > +		rte_free(cb);
> > > > > +	}
> > > > > +
> > > > > +	for (qp = 0; qp < dev->data->nb_queue_pairs; qp++)
> > > > > +		if (dev->enq_cbs[qp] != NULL) {
> > > >
> > > > Some reference count (number of callbacks) seems like a better
> > > > approach here.
> > > Ok.
> > > >
> > > > > +			free_mem = 0;
> > > > > +			break;
> > > > > +		}
> > > > > +
> > > > > +	if (free_mem) {
> > > > > +		rte_free(dev->enq_cbs);
> > > > > +		dev->enq_cbs = NULL;
> > > > > +	}
> > > > > +
> > > > > +	rte_spinlock_unlock(&rte_cryptodev_enq_cb_lock);
> > > > > +
> > > > > +	return ret;
> > > > > +}
> > > > > +#endif
> > > > >
> > > > >  int
> > > > >  rte_cryptodev_sym_session_init(uint8_t dev_id, diff --git
> > > > > a/lib/librte_cryptodev/rte_cryptodev.h
> > > > > b/lib/librte_cryptodev/rte_cryptodev.h
> > > > > index 7b3ebc2..2c7a47b 100644
> > > > > --- a/lib/librte_cryptodev/rte_cryptodev.h
> > > > > +++ b/lib/librte_cryptodev/rte_cryptodev.h
> > > > > @@ -530,6 +530,32 @@ struct rte_cryptodev_qp_conf {  };
> > > > >
> > > > >  /**
> > > > > + * Function type used for pre processing crypto ops when enqueue
> > > > > +burst is
> > > > > + * called.
> > > > > + *
> > > > > + * The callback function is called on enqueue burst immediately
> > > > > + * before the crypto ops are put onto the hardware queue for
> > processing.
> > > > > + *
> > > > > + * @param	dev_id		The identifier of the device.
> > > > > + * @param	qp_id		The index of the queue pair in which
> > ops are
> > > > > + *				to be enqueued for processing. The
> > value
> > > > > + *				must be in the range [0,
> > nb_queue_pairs - 1]
> > > > > + *				previously supplied to
> > > > > + *				*rte_cryptodev_configure*.
> > > > > + * @param	ops		The address of an array of *nb_ops*
> > pointers
> > > > > + *				to *rte_crypto_op* structures which
> > contain
> > > > > + *				the crypto operations to be
> > processed.
> > > > > + * @param	nb_ops		The number of operations to process.
> > > > > + * @param	user_param	The arbitrary user parameter passed
> > in by the
> > > > > + *				application when the callback was
> > originally
> > > > > + *				registered.
> > > > > + * @return			The number of ops to be enqueued
> > to the
> > > > > + *				crypto device.
> > > > > + */
> > > > > +typedef uint16_t (*rte_cryptodev_enq_cb_fn)(uint16_t dev_id,
> > > > > +uint16_t
> > > > qp_id,
> > > > > +		struct rte_crypto_op **ops, uint16_t nb_ops, void
> > > > *user_param);
> > > > > +
> > > > > +/**
> > > > >   * Typedef for application callback function to be registered by
> > application
> > > > >   * software for notification of device events
> > > > >   *
> > > > > @@ -853,7 +879,6 @@ struct rte_cryptodev_config {
> > > > >  		enum rte_cryptodev_event_type event,
> > > > >  		rte_cryptodev_cb_fn cb_fn, void *cb_arg);
> > > > >
> > > > > -
> > > > >  typedef uint16_t (*dequeue_pkt_burst_t)(void *qp,
> > > > >  		struct rte_crypto_op **ops,	uint16_t nb_ops);
> > > > >  /**< Dequeue processed packets from queue pair of a device. */ @@
> > > > > -870,6 +895,17 @@ typedef uint16_t (*enqueue_pkt_burst_t)(void
> > > > > *qp,
> > > > >  /** Structure to keep track of registered callbacks */
> > > > > TAILQ_HEAD(rte_cryptodev_cb_list, rte_cryptodev_callback);
> > > > >
> > > > > +/**
> > > > > + * @internal
> > > > > + * Structure used to hold information about the callbacks to be
> > > > > +called for a
> > > > > + * queue pair on enqueue.
> > > > > + */
> > > > > +struct rte_cryptodev_enq_callback {
> > > > > +	struct rte_cryptodev_enq_callback *next;
> > > > > +	rte_cryptodev_enq_cb_fn fn;
> > > > > +	void *arg;
> > > > > +};
> > > > > +
> > > > >  /** The data structure associated with each crypto device. */
> > > > > struct rte_cryptodev {
> > > > >  	dequeue_pkt_burst_t dequeue_burst; @@ -898,6 +934,14 @@
> > struct
> > > > > rte_cryptodev {
> > > > >  	__extension__
> > > > >  	uint8_t attached : 1;
> > > > >  	/**< Flag indicating the device is attached */
> > > > > +
> > > > > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > > > > +	struct rte_cryptodev_enq_callback **enq_cbs;
> > > > > +	/**< User application callback for pre enqueue processing */
> > > > > +
> > > > > +	struct rte_rcu_qsbr *qsbr;
> > > > > +	/** < RCU QSBR variable for rte_cryptodev_enq_callback */
> > > >
> > > > Probably better to have both these fields per queue.
> > > > Space for them can be allocated at dev_configure() or so.
> > > enq_cbs is allocated during callback add.
> > > Unlike ethdev, each cryptodev have their own max queue pair. There is no
> > macro for that.
> > > I think, single RCU should be good enough, as it has mechanism to track all
> > its reporting threads.
> > >
> > > > BTW, wouldn't it make sense to have ability to add callback for dequeue
> > too?
> > > As mentioned in the commit message, this patch was driven by a
> > requirement.
> > > If required, callback for the dequeue can be added in a separate patch.
> > > >
> > > > > +#endif
> > > > >  } __rte_cache_aligned;
> > > > >
> > > > >  void *
> > > > > @@ -1019,6 +1063,18 @@ struct rte_cryptodev_data {
> > > > >  		struct rte_crypto_op **ops, uint16_t nb_ops)  {
> > > > >  	struct rte_cryptodev *dev = &rte_cryptodevs[dev_id];
> > > > > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > > > > +	if (unlikely(dev->enq_cbs != NULL && dev->enq_cbs[qp_id] !=
> > > > NULL)) {
> > > > > +		struct rte_cryptodev_enq_callback *cb =
> > > > > +			dev->enq_cbs[qp_id];
> > > > > +
> > > > > +		do {
> > > > > +			nb_ops = cb->fn(dev_id, qp_id, ops, nb_ops,
> > > > > +					cb->arg);
> > > > > +			cb = cb->next;
> > > > > +		} while (cb != NULL);
> > > > > +	}
> > > > > +#endif
> > > > >
> > > > >  	rte_cryptodev_trace_enqueue_burst(dev_id, qp_id, (void **)ops,
> > > > nb_ops);
> > > > >  	return (*dev->enqueue_burst)(
> > > > > @@ -1351,6 +1407,102 @@ struct rte_cryptodev_asym_session *
> > > > >  	struct rte_cryptodev_sym_session *sess, union rte_crypto_sym_ofs
> > > > ofs,
> > > > >  	struct rte_crypto_sym_vec *vec);
> > > > >
> > > > > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > > > > +/**
> > > > > + * @warning
> > > > > + * @b EXPERIMENTAL: this API may change without prior notice
> > > > > + *
> > > > > + * Add a user callback for a given crypto device and queue pair
> > > > > +which will be
> > > > > + * called on crypto ops enqueue.
> > > > > + *
> > > > > + * This API configures a function to be called for each burst of
> > > > > +crypto ops
> > > > > + * received on a given crypto device queue pair. The return value
> > > > > +is a pointer
> > > > > + * that can be used later to remove the callback using
> > > > > + * rte_cryptodev_remove_enq_callback().
> > > > > + *
> > > > > + * Multiple functions are called in the order that they are added.
> > > > > + *
> > > > > + * @param	dev_id		The identifier of the device.
> > > > > + * @param	qp_id		The index of the queue pair in which
> > ops are
> > > > > + *				to be enqueued for processing. The
> > value
> > > > > + *				must be in the range [0,
> > nb_queue_pairs - 1]
> > > > > + *				previously supplied to
> > > > > + *				*rte_cryptodev_configure*.
> > > > > + * @param	cb_fn		The callback function
> > > > > + * @param	cb_arg		A generic pointer parameter which
> > will be
> > > > passed
> > > > > + *				to each invocation of the callback
> > function on
> > > > > + *				this crypto device and queue pair.
> > > > > + *
> > > > > + * @return
> > > > > + *   NULL on error.
> > > > > + *   On success, a pointer value which can later be used to remove the
> > > > callback.
> > > > > + */
> > > > > +
> > > > > +__rte_experimental
> > > > > +struct rte_cryptodev_enq_callback *
> > > > > +rte_cryptodev_add_enq_callback(uint8_t dev_id,
> > > > > +			       uint16_t qp_id,
> > > > > +			       rte_cryptodev_enq_cb_fn cb_fn,
> > > > > +			       void *cb_arg);
> > > > > +
> > > > > +
> > > > > +/**
> > > > > + * @warning
> > > > > + * @b EXPERIMENTAL: this API may change without prior notice
> > > > > + *
> > > > > + * Remove a user callback function for given crypto device and queue
> > pair.
> > > > > + *
> > > > > + * This function is used to removed callbacks that were added to
> > > > > +a crypto
> > > > > + * device queue pair using rte_cryptodev_add_enq_callback().
> > > > > + *
> > > > > + * Note: The callback expects a RCU QSBR to be configured to
> > > > > +synchronize
> > > > > + * to free the memory. Application is expected to configure RCU
> > > > > +QSBR after
> > > > > + * adding an enqueue callback.
> > > > > + *
> > > > > + *
> > > > > + * @param	dev_id		The identifier of the device.
> > > > > + * @param	qp_id		The index of the queue pair in which
> > ops are
> > > > > + *				to be enqueued for processing. The
> > value
> > > > > + *				must be in the range [0,
> > nb_queue_pairs - 1]
> > > > > + *				previously supplied to
> > > > > + *				*rte_cryptodev_configure*.
> > > > > + * @param	cb		Pointer to user supplied callback
> > created via
> > > > > + *				rte_cryptodev_add_enq_callback().
> > > > > + *
> > > > > + * @return
> > > > > + *   - 0: Success. Callback was removed.
> > > > > + *   - -EINVAL:  The dev_id or the qp_id is out of range, or the callback
> > > > > + *               is NULL or not found for the crypto device queue pair.
> > > > > + */
> > > > > +
> > > > > +__rte_experimental
> > > > > +int rte_cryptodev_remove_enq_callback(uint8_t dev_id,
> > > > > +				  uint16_t qp_id,
> > > > > +				  struct rte_cryptodev_enq_callback *cb);
> > > > > +
> > > > > +
> > > > > +/**
> > > > > + * @warning
> > > > > + * @b EXPERIMENTAL: this API may change without prior notice
> > > > > + *
> > > > > + * Associate RCU QSBR variable with a cryptodev.
> > > > > + *
> > > > > + * This function is used to add RCU QSBR to a crypto device.
> > > > > + * The purpose of RCU is to help multiple threads to synchronize
> > > > > + * with each other before initiating adding/removing callback
> > > > > + * while dataplane threads are running enqueue callbacks.
> > > > > + *
> > > > > + * @param	dev_id		The identifier of the device.
> > > > > + * @param	qsr		RCU QSBR configuration
> > > > > + * @return
> > > > > + *   On success - 0
> > > > > + *   On error - EINVAL.
> > > > > + */
> > > > > +
> > > > > +__rte_experimental
> > > > > +int rte_cryptodev_rcu_qsbr_add(uint8_t dev_id, struct
> > > > > +rte_rcu_qsbr *qsbr); #endif
> > > > > +
> > > > >  #ifdef __cplusplus
> > > > >  }
> > > > >  #endif
> > > > > diff --git a/lib/librte_cryptodev/rte_cryptodev_version.map
> > > > > b/lib/librte_cryptodev/rte_cryptodev_version.map
> > > > > index 02f6dcf..46de3ca 100644
> > > > > --- a/lib/librte_cryptodev/rte_cryptodev_version.map
> > > > > +++ b/lib/librte_cryptodev/rte_cryptodev_version.map
> > > > > @@ -64,6 +64,7 @@ DPDK_20.0 {
> > > > >  	rte_cryptodev_sym_capability_get;  };
> > > > >
> > > > > +
> > > > >  EXPERIMENTAL {
> > > > >  	global:
> > > > >
> > > > > @@ -105,4 +106,9 @@ EXPERIMENTAL {
> > > > >
> > > > >  	# added in 20.08
> > > > >  	rte_cryptodev_get_qp_status;
> > > > > +
> > > > > +	# added in 20.11
> > > > > +	rte_cryptodev_add_enq_callback;
> > > > > +	rte_cryptodev_remove_enq_callback;
> > > > > +	rte_cryptodev_rcu_qsbr_add;
> > > > >  };
> > > > > --
> > > > > 1.9.1