Re: [PATCH v1 13/14] xprtrdma: Stack relief in fmr_op_map()

[Sagi Grimberg <sagig@dev.mellanox.co.il>]

On 5/4/2015 8:58 PM, Chuck Lever wrote:
> fmr_op_map() declares a 64 element array of u64 in automatic
> storage. This is 512 bytes (8 * 64) on the stack.
>
> Instead, when FMR memory registration is in use, pre-allocate a
> physaddr array for each rpcrdma_mw.
>
> This is a pre-requisite for increasing the r/wsize maximum for
> FMR on platforms with 4KB pages.
>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>   net/sunrpc/xprtrdma/fmr_ops.c   |   32 ++++++++++++++++++++++----------
>   net/sunrpc/xprtrdma/xprt_rdma.h |    7 ++++++-
>   2 files changed, 28 insertions(+), 11 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
> index 52f9ad5..4a53ad5 100644
> --- a/net/sunrpc/xprtrdma/fmr_ops.c
> +++ b/net/sunrpc/xprtrdma/fmr_ops.c
> @@ -72,13 +72,19 @@ fmr_op_init(struct rpcrdma_xprt *r_xprt)
>   	i = (buf->rb_max_requests + 1) * RPCRDMA_MAX_SEGS;
>   	dprintk("RPC:       %s: initializing %d FMRs\n", __func__, i);
>
> +	rc = -ENOMEM;
>   	while (i--) {
>   		r = kzalloc(sizeof(*r), GFP_KERNEL);
>   		if (!r)
> -			return -ENOMEM;
> +			goto out;
> +
> +		r->r.fmr.physaddrs = kmalloc(RPCRDMA_MAX_FMR_SGES *
> +					     sizeof(u64), GFP_KERNEL);
> +		if (!r->r.fmr.physaddrs)
> +			goto out_free;
>
> -		r->r.fmr = ib_alloc_fmr(pd, mr_access_flags, &fmr_attr);
> -		if (IS_ERR(r->r.fmr))
> +		r->r.fmr.fmr = ib_alloc_fmr(pd, mr_access_flags, &fmr_attr);
> +		if (IS_ERR(r->r.fmr.fmr))
>   			goto out_fmr_err;
>
>   		list_add(&r->mw_list, &buf->rb_mws);
> @@ -87,9 +93,12 @@ fmr_op_init(struct rpcrdma_xprt *r_xprt)
>   	return 0;
>
>   out_fmr_err:
> -	rc = PTR_ERR(r->r.fmr);
> +	rc = PTR_ERR(r->r.fmr.fmr);
>   	dprintk("RPC:       %s: ib_alloc_fmr status %i\n", __func__, rc);
> +	kfree(r->r.fmr.physaddrs);
> +out_free:
>   	kfree(r);
> +out:
>   	return rc;
>   }
>
> @@ -98,7 +107,7 @@ __fmr_unmap(struct rpcrdma_mw *r)
>   {
>   	LIST_HEAD(l);
>
> -	list_add(&r->r.fmr->list, &l);
> +	list_add(&r->r.fmr.fmr->list, &l);
>   	return ib_unmap_fmr(&l);
>   }
>
> @@ -113,7 +122,6 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
>   	struct ib_device *device = ia->ri_device;
>   	enum dma_data_direction direction = rpcrdma_data_dir(writing);
>   	struct rpcrdma_mr_seg *seg1 = seg;
> -	u64 physaddrs[RPCRDMA_MAX_DATA_SEGS];
>   	int len, pageoff, i, rc;
>   	struct rpcrdma_mw *mw;
>
> @@ -138,7 +146,7 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
>   		nsegs = RPCRDMA_MAX_FMR_SGES;
>   	for (i = 0; i < nsegs;) {
>   		rpcrdma_map_one(device, seg, direction);
> -		physaddrs[i] = seg->mr_dma;
> +		mw->r.fmr.physaddrs[i] = seg->mr_dma;
>   		len += seg->mr_len;
>   		++seg;
>   		++i;
> @@ -148,12 +156,13 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
>   			break;
>   	}
>
> -	rc = ib_map_phys_fmr(mw->r.fmr, physaddrs, i, seg1->mr_dma);
> +	rc = ib_map_phys_fmr(mw->r.fmr.fmr, mw->r.fmr.physaddrs,
> +			     i, seg1->mr_dma);
>   	if (rc)
>   		goto out_maperr;
>
>   	seg1->rl_mw = mw;
> -	seg1->mr_rkey = mw->r.fmr->rkey;
> +	seg1->mr_rkey = mw->r.fmr.fmr->rkey;
>   	seg1->mr_base = seg1->mr_dma + pageoff;
>   	seg1->mr_nsegs = i;
>   	seg1->mr_len = len;
> @@ -207,10 +216,13 @@ fmr_op_destroy(struct rpcrdma_buffer *buf)
>   	while (!list_empty(&buf->rb_all)) {
>   		r = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
>   		list_del(&r->mw_all);
> -		rc = ib_dealloc_fmr(r->r.fmr);
> +		kfree(r->r.fmr.physaddrs);
> +
> +		rc = ib_dealloc_fmr(r->r.fmr.fmr);
>   		if (rc)
>   			dprintk("RPC:       %s: ib_dealloc_fmr failed %i\n",
>   				__func__, rc);
> +
>   		kfree(r);
>   	}
>   }
> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
> index ae31fc7..e176bae 100644
> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
> @@ -207,9 +207,14 @@ struct rpcrdma_frmr {
>   	struct rpcrdma_xprt		*fr_xprt;
>   };
>
> +struct rpcrdma_fmr {
> +	struct ib_fmr		*fmr;
> +	u64			*physaddrs;
> +};
> +
>   struct rpcrdma_mw {
>   	union {
> -		struct ib_fmr		*fmr;
> +		struct rpcrdma_fmr	fmr;
>   		struct rpcrdma_frmr	frmr;
>   	} r;
>   	void			(*mw_sendcompletion)(struct ib_wc *);
>

Looks good

Reviewed-by: Sagi Grimberg <sagig@mellanox.com>