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

Chuck Lever
2015-05-04T17:58:46Z

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-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
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 *);

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