Re: [PATCH v3 01/12] IB/core: Guarantee that a local_dma_lkey is available

["ira.weiny" <ira.weiny@intel.com>]

On Tue, Aug 04, 2015 at 04:21:30PM -0600, Jason Gunthorpe wrote:
> Every single ULP requires a local_dma_lkey to do anything with
> a QP, so let us ensure one exists for every PD created.
> 
> If the driver can supply a global local_dma_lkey then use that, otherwise
> ask the driver to create a local use all physical memory MR associated
> with the new PD.
> 
> Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
> Reviewed-by: Sagi Grimberg <sagig@dev.mellanox.co.il>
> Acked-by: Christoph Hellwig <hch@infradead.org>
> Reviewed-by: Steve Wise <swise@opengridcomputing.com>

I hit this bug as well.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Ira Weiny <ira.weiny@intel.com>


> ---
>  drivers/infiniband/core/uverbs_cmd.c |  1 +
>  drivers/infiniband/core/verbs.c      | 47 ++++++++++++++++++++++++++++++++----
>  include/rdma/ib_verbs.h              |  9 ++-----
>  3 files changed, 45 insertions(+), 12 deletions(-)
> 
> This has the extra null assignment in uverbs that Haggai discovered. No changes
> to other patches in the series.
> 
> I also wrote a cleanup patch for ib_dealloc_pd:
> 
>  https://github.com/jgunthorpe/linux/commit/7ea87a7f394c2113cc2232edfe785089eb0aea32
> 
> I'll post it when I've tested it a bit..
> 
> diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> index bbb02ffe87df..258485ee46b2 100644
> --- a/drivers/infiniband/core/uverbs_cmd.c
> +++ b/drivers/infiniband/core/uverbs_cmd.c
> @@ -562,6 +562,7 @@ ssize_t ib_uverbs_alloc_pd(struct ib_uverbs_file *file,
>  
>  	pd->device  = file->device->ib_dev;
>  	pd->uobject = uobj;
> +	pd->local_mr = NULL;
>  	atomic_set(&pd->usecnt, 0);
>  
>  	uobj->object = pd;
> diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
> index bac3fb406a74..e9d72a28a9a5 100644
> --- a/drivers/infiniband/core/verbs.c
> +++ b/drivers/infiniband/core/verbs.c
> @@ -213,18 +213,49 @@ EXPORT_SYMBOL(rdma_port_get_link_layer);
>  
>  /* Protection domains */
>  
> +/**
> + * ib_alloc_pd - Allocates an unused protection domain.
> + * @device: The device on which to allocate the protection domain.
> + *
> + * A protection domain object provides an association between QPs, shared
> + * receive queues, address handles, memory regions, and memory windows.
> + *
> + * Every PD has a local_dma_lkey which can be used as the lkey value for local
> + * memory operations.
> + */
>  struct ib_pd *ib_alloc_pd(struct ib_device *device)
>  {
>  	struct ib_pd *pd;
> +	struct ib_device_attr devattr;
> +	int rc;
> +
> +	rc = ib_query_device(device, &devattr);
> +	if (rc)
> +		return ERR_PTR(rc);
>  
>  	pd = device->alloc_pd(device, NULL, NULL);
> +	if (IS_ERR(pd))
> +		return pd;
> +
> +	pd->device = device;
> +	pd->uobject = NULL;
> +	pd->local_mr = NULL;
> +	atomic_set(&pd->usecnt, 0);
> +
> +	if (devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
> +		pd->local_dma_lkey = device->local_dma_lkey;
> +	else {
> +		struct ib_mr *mr;
> +
> +		mr = ib_get_dma_mr(pd, IB_ACCESS_LOCAL_WRITE);
> +		if (IS_ERR(mr)) {
> +			ib_dealloc_pd(pd);
> +			return (struct ib_pd *)mr;
> +		}
>  
> -	if (!IS_ERR(pd)) {
> -		pd->device  = device;
> -		pd->uobject = NULL;
> -		atomic_set(&pd->usecnt, 0);
> +		pd->local_mr = mr;
> +		pd->local_dma_lkey = pd->local_mr->lkey;
>  	}
> -
>  	return pd;
>  }
>  EXPORT_SYMBOL(ib_alloc_pd);
> @@ -234,6 +265,12 @@ int ib_dealloc_pd(struct ib_pd *pd)
>  	if (atomic_read(&pd->usecnt))
>  		return -EBUSY;
>  
> +	if (pd->local_mr) {
> +		if (ib_dereg_mr(pd->local_mr))
> +			return -EBUSY;
> +		pd->local_mr = NULL;
> +	}
> +
>  	return pd->device->dealloc_pd(pd);
>  }
>  EXPORT_SYMBOL(ib_dealloc_pd);
> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> index b0f898e3b2e7..eaec3081fb87 100644
> --- a/include/rdma/ib_verbs.h
> +++ b/include/rdma/ib_verbs.h
> @@ -1252,9 +1252,11 @@ struct ib_udata {
>  };
>  
>  struct ib_pd {
> +	u32			local_dma_lkey;
>  	struct ib_device       *device;
>  	struct ib_uobject      *uobject;
>  	atomic_t          	usecnt; /* count all resources */
> +	struct ib_mr	       *local_mr;
>  };
>  
>  struct ib_xrcd {
> @@ -2135,13 +2137,6 @@ int ib_find_gid(struct ib_device *device, union ib_gid *gid,
>  int ib_find_pkey(struct ib_device *device,
>  		 u8 port_num, u16 pkey, u16 *index);
>  
> -/**
> - * ib_alloc_pd - Allocates an unused protection domain.
> - * @device: The device on which to allocate the protection domain.
> - *
> - * A protection domain object provides an association between QPs, shared
> - * receive queues, address handles, memory regions, and memory windows.
> - */
>  struct ib_pd *ib_alloc_pd(struct ib_device *device);
>  
>  /**
> -- 
> 1.9.1
> 
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