[RFC PATCH bpf-next 03/12] xsk: introduce xdp_umem_frame

[Björn Töpel]

From: Björn Töpel <bjorn.to...@intel.com>

The xdp_umem_frame holds the address for a frame. Trade memory for
faster lookup. Later, we'll add DMA address here as well.

Signed-off-by: Björn Töpel <bjorn.to...@intel.com>
---
 include/net/xdp_sock.h |  8 +++++---
 net/xdp/xdp_umem.c     | 29 +++++++++++++++++++++++++----
 net/xdp/xdp_umem.h     |  9 +--------
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index c959aa43fb01..09068c4f068e 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -29,16 +29,18 @@ struct xdp_umem_props {
        u32 nframes;
 };
 
+struct xdp_umem_frame {
+       void *addr;
+};
+
 struct xdp_umem {
        struct xsk_queue *fq;
        struct xsk_queue *cq;
+       struct xdp_umem_frame *frames;
        struct page **pgs;
        struct xdp_umem_props props;
        u32 npgs;
        u32 frame_headroom;
-       u32 nfpp_mask;
-       u32 nfpplog2;
-       u32 frame_size_log2;
        struct user_struct *user;
        struct pid *pid;
        unsigned long address;
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 7cc162799744..b426cbe3151a 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -92,6 +92,9 @@ static void xdp_umem_release(struct xdp_umem *umem)
                umem->pgs = NULL;
        }
 
+       kfree(umem->frames);
+       umem->frames = NULL;
+
        xdp_umem_unaccount_pages(umem);
 out:
        kfree(umem);
@@ -181,7 +184,8 @@ int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg 
*mr)
 {
        u32 frame_size = mr->frame_size, frame_headroom = mr->frame_headroom;
        u64 addr = mr->addr, size = mr->len;
-       unsigned int nframes, nfpp;
+       u32 nfpplog2, frame_size_log2;
+       unsigned int nframes, nfpp, i;
        int size_chk, err;
 
        if (!umem)
@@ -234,9 +238,6 @@ int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg 
*mr)
        umem->pgs = NULL;
        umem->user = NULL;
 
-       umem->frame_size_log2 = ilog2(frame_size);
-       umem->nfpp_mask = nfpp - 1;
-       umem->nfpplog2 = ilog2(nfpp);
        atomic_set(&umem->users, 1);
 
        err = xdp_umem_account_pages(umem);
@@ -246,6 +247,26 @@ int xdp_umem_reg(struct xdp_umem *umem, struct 
xdp_umem_reg *mr)
        err = xdp_umem_pin_pages(umem);
        if (err)
                goto out_account;
+
+       umem->frames = kcalloc(nframes, sizeof(*umem->frames), GFP_KERNEL);
+       if (!umem->frames) {
+               err = -ENOMEM;
+               goto out_account;
+       }
+
+       frame_size_log2 = ilog2(frame_size);
+       nfpplog2 = ilog2(nfpp);
+       for (i = 0; i < nframes; i++) {
+               u64 pg, off;
+               char *data;
+
+               pg = i >> nfpplog2;
+               off = (i & (nfpp - 1)) << frame_size_log2;
+
+               data = page_address(umem->pgs[pg]);
+               umem->frames[i].addr = data + off;
+       }
+
        return 0;
 
 out_account:
diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
index 32ad59b7322f..0a969384af93 100644
--- a/net/xdp/xdp_umem.h
+++ b/net/xdp/xdp_umem.h
@@ -19,14 +19,7 @@
 
 static inline char *xdp_umem_get_data(struct xdp_umem *umem, u32 idx)
 {
-       u64 pg, off;
-       char *data;
-
-       pg = idx >> umem->nfpplog2;
-       off = (idx & umem->nfpp_mask) << umem->frame_size_log2;
-
-       data = page_address(umem->pgs[pg]);
-       return data + off;
+       return umem->frames[idx].addr;
 }
 
 static inline char *xdp_umem_get_data_with_headroom(struct xdp_umem *umem,
-- 
2.14.1