[PATCH bpf-next 02/11] xsk: introduce xdp_umem_page

[Björn Töpel]

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

The xdp_umem_page holds the address for a page. 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 |  7 ++++++-
 net/xdp/xdp_umem.c     | 15 ++++++++++++++-
 net/xdp/xdp_umem.h     |  3 +--
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 3a6cd88f179d..caf343a7e224 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -20,10 +20,14 @@ struct xdp_umem_props {
        u64 size;
 };
 
+struct xdp_umem_page {
+       void *addr;
+};
+
 struct xdp_umem {
        struct xsk_queue *fq;
        struct xsk_queue *cq;
-       struct page **pgs;
+       struct xdp_umem_page *pages;
        struct xdp_umem_props props;
        u32 headroom;
        u32 chunk_size_nohr;
@@ -32,6 +36,7 @@ struct xdp_umem {
        unsigned long address;
        refcount_t users;
        struct work_struct work;
+       struct page **pgs;
        u32 npgs;
 };
 
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 2793a503223e..aca826011f6c 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -65,6 +65,9 @@ static void xdp_umem_release(struct xdp_umem *umem)
                goto out;
 
        mmput(mm);
+       kfree(umem->pages);
+       umem->pages = NULL;
+
        xdp_umem_unaccount_pages(umem);
 out:
        kfree(umem);
@@ -155,7 +158,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct 
xdp_umem_reg *mr)
        u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
        unsigned int chunks, chunks_per_page;
        u64 addr = mr->addr, size = mr->len;
-       int size_chk, err;
+       int size_chk, err, i;
 
        if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
                /* Strictly speaking we could support this, if:
@@ -213,6 +216,16 @@ static 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->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL);
+       if (!umem->pages) {
+               err = -ENOMEM;
+               goto out_account;
+       }
+
+       for (i = 0; i < umem->npgs; i++)
+               umem->pages[i].addr = page_address(umem->pgs[i]);
+
        return 0;
 
 out_account:
diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
index 9433e8af650a..40e8fa4a92af 100644
--- a/net/xdp/xdp_umem.h
+++ b/net/xdp/xdp_umem.h
@@ -10,8 +10,7 @@
 
 static inline char *xdp_umem_get_data(struct xdp_umem *umem, u64 addr)
 {
-       return page_address(umem->pgs[addr >> PAGE_SHIFT]) +
-               (addr & (PAGE_SIZE - 1));
+       return umem->pages[addr >> PAGE_SHIFT].addr + (addr & (PAGE_SIZE - 1));
 }
 
 bool xdp_umem_validate_queues(struct xdp_umem *umem);
-- 
2.14.1