Re: [PATCH for-next 3/4] RDMA/hns: Support rq record doorbell for kernel space

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Wed, Jan 24, 2018 at 08:40:42PM +0800, Liuyixian (Eason) wrote:
>
>
> On 2018/1/23 19:07, Leon Romanovsky wrote:
> > On Thu, Jan 18, 2018 at 10:34:30AM +0800, Yixian Liu wrote:
> >> This patch updates to support rq record doorbell for
> >> the kernel space.
> >>
> >> Signed-off-by: Yixian Liu <liuyixian-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> >> Signed-off-by: Lijun Ou <oulijun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> >> Signed-off-by: Wei Hu (Xavier) <xavier.huwei-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> >> Signed-off-by: Shaobo Xu <xushaobo2-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> >> ---
> >>  drivers/infiniband/hw/hns/hns_roce_db.c     | 112 ++++++++++++++++++++++++++++
> >>  drivers/infiniband/hw/hns/hns_roce_device.h |   6 ++
> >>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c  |  15 +---
> >>  drivers/infiniband/hw/hns/hns_roce_main.c   |   5 ++
> >>  drivers/infiniband/hw/hns/hns_roce_qp.c     |  18 ++++-
> >>  5 files changed, 143 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/drivers/infiniband/hw/hns/hns_roce_db.c b/drivers/infiniband/hw/hns/hns_roce_db.c
> >> index 0908208..de3fa94 100644
> >> --- a/drivers/infiniband/hw/hns/hns_roce_db.c
> >> +++ b/drivers/infiniband/hw/hns/hns_roce_db.c
> >> @@ -92,3 +92,115 @@ void hns_roce_db_unmap_user(struct hns_roce_ucontext *context,
> >>  	mutex_unlock(&context->db_page_mutex);
> >>  }
> >>  EXPORT_SYMBOL(hns_roce_db_unmap_user);
> >> +
> >> +static struct hns_roce_db_pgdir *hns_roce_alloc_db_pgdir(
> >> +					struct device *dma_device, gfp_t gfp)
> >> +{
> >> +	struct hns_roce_db_pgdir *pgdir;
> >> +
> >> +	pgdir = kzalloc(sizeof(*pgdir), gfp);
> >> +	if (!pgdir)
> >> +		return NULL;
> >> +
> >> +	bitmap_fill(pgdir->order1, HNS_ROCE_DB_PER_PAGE / 2);
> >> +	pgdir->bits[0] = pgdir->order0;
> >
> > order0? isn't it equal to zero?
> >
>
> No. Here order0 is the name of a bitmap array and bits[0] points to it.

pgdir was allocated with kzalloc() -> all fields are zero ->
pgdir->order0 == 0 or pgdir->order0 == NULL -> What is the point in such
assignment?

Thanks

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