Re: [PATCH v7 04/25] RDMA/rtrs: core: lib functions shared between client and server modules

Jinpu Wang
2020-01-20T14:08:12Z

On Mon, Jan 20, 2020 at 2:30 PM Leon Romanovsky <leon@kernel.org> wrote:
>
> On Mon, Jan 20, 2020 at 12:32:00PM +0100, Jinpu Wang wrote:
> > On Sun, Jan 19, 2020 at 3:48 PM Leon Romanovsky <leon@kernel.org> wrote:
> > >
> > > On Thu, Jan 16, 2020 at 01:58:54PM +0100, Jack Wang wrote:
> > > > From: Jack Wang <jinpu.wang@cloud.ionos.com>
> > > >
> > > > This is a set of library functions existing as a rtrs-core module,
> > > > used by client and server modules.
> > > >
> > > > Mainly these functions wrap IB and RDMA calls and provide a bit higher
> > > > abstraction for implementing of RTRS protocol on client or server
> > > > sides.
> > > >
> > > > Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
> > > > Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
> > > > ---
> > > > drivers/infiniband/ulp/rtrs/rtrs.c | 597 +++++++++++++++++++++++++++++
> > > > 1 file changed, 597 insertions(+)
> > > > create mode 100644 drivers/infiniband/ulp/rtrs/rtrs.c
> > > >
> > > > diff --git a/drivers/infiniband/ulp/rtrs/rtrs.c b/drivers/infiniband/ulp/rtrs/rtrs.c
> > > > new file mode 100644
> > > > index 000000000000..7b84d76e2a67
> > > > --- /dev/null
> > > > +++ b/drivers/infiniband/ulp/rtrs/rtrs.c
> > > > @@ -0,0 +1,597 @@
> > > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > > +/*
> > > > + * RDMA Transport Layer
> > > > + *
> > > > + * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
> > > > + *
> > > > + * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
> > > > + *
> > > > + * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
> > > > + */
> > > > +#undef pr_fmt
> > > > +#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
> > > > +
> > > > +#include <linux/module.h>
> > > > +#include <linux/inet.h>
> > > > +
> > > > +#include "rtrs-pri.h"
> > > > +#include "rtrs-log.h"
> > > > +
> > > > +MODULE_DESCRIPTION("RDMA Transport Core");
> > > > +MODULE_LICENSE("GPL");
> > > > +
> > > > +struct rtrs_iu *rtrs_iu_alloc(u32 queue_size, size_t size, gfp_t gfp_mask,
> > > > + struct ib_device *dma_dev,
> > > > + enum dma_data_direction dir,
> > > > + void (*done)(struct ib_cq *cq, struct ib_wc *wc))
> > > > +{
> > > > + struct rtrs_iu *ius, *iu;
> > > > + int i;
> > > > +
> > > > + WARN_ON(!queue_size);
> > > > + ius = kcalloc(queue_size, sizeof(*ius), gfp_mask);
> > > > + if (unlikely(!ius))
> > > > + return NULL;
> > >
> > > Let's do not add useless WARN_ON() and unlikely to every error path.
> > I can remove the WARN_ON, but the unlikey for error case seems normal to use,
> > small size memory allocation is unlikely to fail.
>
> The unlikely() makes sense in data-path only and mostly it doesn't give
> any performance advantage, kcalloc() in this function means that this
> function is not performance oriented.
>

Thanks for the clarification, it is not in the data path, sure can be
removed, we will review the usage
and remove the unnecessary ones.