Re: [PATCH 1/5] IB/core: add a simple SRQ set per PD

[Leon Romanovsky <leonro@mellanox.com>]

On Tue, Mar 17, 2020 at 03:40:26PM +0200, Max Gurtovoy wrote:
> ULP's can use this API to create/destroy SRQ's with the same
> characteristics for implementing a logic that aimed to save resources
> without significant performance penalty (e.g. create SRQ per completion
> vector and use shared receive buffers for multiple controllers of the
> ULP).
>
> Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
> ---
>  drivers/infiniband/core/Makefile  |  2 +-
>  drivers/infiniband/core/srq_set.c | 78 +++++++++++++++++++++++++++++++++++++++
>  drivers/infiniband/core/verbs.c   |  4 ++
>  include/rdma/ib_verbs.h           |  5 +++
>  include/rdma/srq_set.h            | 18 +++++++++
>  5 files changed, 106 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/infiniband/core/srq_set.c
>  create mode 100644 include/rdma/srq_set.h
>
> diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
> index d1b14887..1d3eaec 100644
> --- a/drivers/infiniband/core/Makefile
> +++ b/drivers/infiniband/core/Makefile
> @@ -12,7 +12,7 @@ ib_core-y :=			packer.o ud_header.o verbs.o cq.o rw.o sysfs.o \
>  				roce_gid_mgmt.o mr_pool.o addr.o sa_query.o \
>  				multicast.o mad.o smi.o agent.o mad_rmpp.o \
>  				nldev.o restrack.o counters.o ib_core_uverbs.o \
> -				trace.o
> +				trace.o srq_set.o

Why did you call it "srq_set.c" and not "srq.c"?

>
>  ib_core-$(CONFIG_SECURITY_INFINIBAND) += security.o
>  ib_core-$(CONFIG_CGROUP_RDMA) += cgroup.o
> diff --git a/drivers/infiniband/core/srq_set.c b/drivers/infiniband/core/srq_set.c
> new file mode 100644
> index 0000000..d143561
> --- /dev/null
> +++ b/drivers/infiniband/core/srq_set.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
> +/*
> + * Copyright (c) 2020 Mellanox Technologies. All rights reserved.
> + */
> +
> +#include <rdma/srq_set.h>
> +
> +struct ib_srq *rdma_srq_get(struct ib_pd *pd)
> +{
> +	struct ib_srq *srq;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pd->srq_lock, flags);
> +	srq = list_first_entry_or_null(&pd->srqs, struct ib_srq, pd_entry);
> +	if (srq) {
> +		list_del(&srq->pd_entry);
> +		pd->srqs_used++;

I don't see any real usage of srqs_used.

> +	}
> +	spin_unlock_irqrestore(&pd->srq_lock, flags);
> +
> +	return srq;
> +}
> +EXPORT_SYMBOL(rdma_srq_get);
> +
> +void rdma_srq_put(struct ib_pd *pd, struct ib_srq *srq)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pd->srq_lock, flags);
> +	list_add(&srq->pd_entry, &pd->srqs);
> +	pd->srqs_used--;
> +	spin_unlock_irqrestore(&pd->srq_lock, flags);
> +}
> +EXPORT_SYMBOL(rdma_srq_put);
> +
> +int rdma_srq_set_init(struct ib_pd *pd, int nr,
> +		struct ib_srq_init_attr *srq_attr)
> +{
> +	struct ib_srq *srq;
> +	unsigned long flags;
> +	int ret, i;
> +
> +	for (i = 0; i < nr; i++) {
> +		srq = ib_create_srq(pd, srq_attr);
> +		if (IS_ERR(srq)) {
> +			ret = PTR_ERR(srq);
> +			goto out;
> +		}
> +
> +		spin_lock_irqsave(&pd->srq_lock, flags);
> +		list_add_tail(&srq->pd_entry, &pd->srqs);
> +		spin_unlock_irqrestore(&pd->srq_lock, flags);
> +	}
> +
> +	return 0;
> +out:
> +	rdma_srq_set_destroy(pd);
> +	return ret;
> +}
> +EXPORT_SYMBOL(rdma_srq_set_init);
> +
> +void rdma_srq_set_destroy(struct ib_pd *pd)
> +{
> +	struct ib_srq *srq;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pd->srq_lock, flags);
> +	while (!list_empty(&pd->srqs)) {
> +		srq = list_first_entry(&pd->srqs, struct ib_srq, pd_entry);
> +		list_del(&srq->pd_entry);
> +
> +		spin_unlock_irqrestore(&pd->srq_lock, flags);
> +		ib_destroy_srq(srq);
> +		spin_lock_irqsave(&pd->srq_lock, flags);
> +	}
> +	spin_unlock_irqrestore(&pd->srq_lock, flags);
> +}
> +EXPORT_SYMBOL(rdma_srq_set_destroy);
> diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
> index e62c9df..6950abf 100644
> --- a/drivers/infiniband/core/verbs.c
> +++ b/drivers/infiniband/core/verbs.c
> @@ -272,6 +272,9 @@ struct ib_pd *__ib_alloc_pd(struct ib_device *device, unsigned int flags,
>  	pd->__internal_mr = NULL;
>  	atomic_set(&pd->usecnt, 0);
>  	pd->flags = flags;
> +	pd->srqs_used = 0;
> +	spin_lock_init(&pd->srq_lock);
> +	INIT_LIST_HEAD(&pd->srqs);
>
>  	pd->res.type = RDMA_RESTRACK_PD;
>  	rdma_restrack_set_task(&pd->res, caller);
> @@ -340,6 +343,7 @@ void ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata)
>  		pd->__internal_mr = NULL;
>  	}
>
> +	WARN_ON_ONCE(pd->srqs_used > 0);

It can be achieved by WARN_ON_ONCE(!list_empty(&pd->srqs))

>  	/* uverbs manipulates usecnt with proper locking, while the kabi
>  	   requires the caller to guarantee we can't race here. */
>  	WARN_ON(atomic_read(&pd->usecnt));
> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> index 1f779fa..fc8207d 100644
> --- a/include/rdma/ib_verbs.h
> +++ b/include/rdma/ib_verbs.h
> @@ -1517,6 +1517,10 @@ struct ib_pd {
>
>  	u32			unsafe_global_rkey;
>
> +	spinlock_t		srq_lock;
> +	int			srqs_used;
> +	struct list_head	srqs;
> +
>  	/*
>  	 * Implementation details of the RDMA core, don't use in drivers:
>  	 */
> @@ -1585,6 +1589,7 @@ struct ib_srq {
>  	void		       *srq_context;
>  	enum ib_srq_type	srq_type;
>  	atomic_t		usecnt;
> +	struct list_head	pd_entry; /* srq set entry */
>
>  	struct {
>  		struct ib_cq   *cq;
> diff --git a/include/rdma/srq_set.h b/include/rdma/srq_set.h
> new file mode 100644
> index 0000000..834c4c6
> --- /dev/null
> +++ b/include/rdma/srq_set.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: (GPL-2.0 OR Linux-OpenIB) */
> +/*
> + * Copyright (c) 2020 Mellanox Technologies. All rights reserved.
> + */
> +
> +#ifndef _RDMA_SRQ_SET_H
> +#define _RDMA_SRQ_SET_H 1

"1" is not needed.

> +
> +#include <rdma/ib_verbs.h>
> +
> +struct ib_srq *rdma_srq_get(struct ib_pd *pd);
> +void rdma_srq_put(struct ib_pd *pd, struct ib_srq *srq);

At the end, it is not get/put semantics but more add/remove.

Thanks

> +
> +int rdma_srq_set_init(struct ib_pd *pd, int nr,
> +		struct ib_srq_init_attr *srq_attr);
> +void rdma_srq_set_destroy(struct ib_pd *pd);
> +
> +#endif /* _RDMA_SRQ_SET_H */
> --
> 1.8.3.1
>

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