xdp: introduce xdp_return_frame API and use in cpumap

Introduce an xdp_return_frame API, and convert over cpumap as
the first user, given it have queued XDP frame structure to leverage.

V3: Cleanup and remove C99 style comments, pointed out by Alex Duyck.
V6: Remove comment that id will be added later (Req by Alex Duyck)
V8: Rename enum mem_type to xdp_mem_type (found by kbuild test robot)

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/xdp.h b/include/net/xdp.h
index b2362dd..e420769 100644 (file)
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -33,16 +33,43 @@
  * also mandatory during RX-ring setup.
  */
 
+enum xdp_mem_type {
+       MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
+       MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
+       MEM_TYPE_MAX,
+};
+
+struct xdp_mem_info {
+       u32 type; /* enum xdp_mem_type, but known size type */
+};
+
 struct xdp_rxq_info {
        struct net_device *dev;
        u32 queue_index;
        u32 reg_state;
+       struct xdp_mem_info mem;
 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
 
+
+static inline
+void xdp_return_frame(void *data, struct xdp_mem_info *mem)
+{
+       if (mem->type == MEM_TYPE_PAGE_SHARED)
+               page_frag_free(data);
+
+       if (mem->type == MEM_TYPE_PAGE_ORDER0) {
+               struct page *page = virt_to_page(data); /* Assumes order0 page*/
+
+               put_page(page);
+       }
+}
+
 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
                     struct net_device *dev, u32 queue_index);
 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
+int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
+                              enum xdp_mem_type type, void *allocator);
 
 #endif /* __LINUX_NET_XDP_H__ */

diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index a4bb0b3..3e4bbcb 100644 (file)
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -19,6 +19,7 @@
 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <linux/ptr_ring.h>
+#include <net/xdp.h>
 
 #include <linux/sched.h>
 #include <linux/workqueue.h>
@@ -137,27 +138,6 @@ free_cmap:
        return ERR_PTR(err);
 }
 
-static void __cpu_map_queue_destructor(void *ptr)
-{
-       /* The tear-down procedure should have made sure that queue is
-        * empty.  See __cpu_map_entry_replace() and work-queue
-        * invoked cpu_map_kthread_stop(). Catch any broken behaviour
-        * gracefully and warn once.
-        */
-       if (WARN_ON_ONCE(ptr))
-               page_frag_free(ptr);
-}
-
-static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu)
-{
-       if (atomic_dec_and_test(&rcpu->refcnt)) {
-               /* The queue should be empty at this point */
-               ptr_ring_cleanup(rcpu->queue, __cpu_map_queue_destructor);
-               kfree(rcpu->queue);
-               kfree(rcpu);
-       }
-}
-
 static void get_cpu_map_entry(struct bpf_cpu_map_entry *rcpu)
 {
        atomic_inc(&rcpu->refcnt);
@@ -188,6 +168,10 @@ struct xdp_pkt {
        u16 len;
        u16 headroom;
        u16 metasize;
+       /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
+        * while mem info is valid on remote CPU.
+        */
+       struct xdp_mem_info mem;
        struct net_device *dev_rx;
 };
 
@@ -213,6 +197,9 @@ static struct xdp_pkt *convert_to_xdp_pkt(struct xdp_buff *xdp)
        xdp_pkt->headroom = headroom - sizeof(*xdp_pkt);
        xdp_pkt->metasize = metasize;
 
+       /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
+       xdp_pkt->mem = xdp->rxq->mem;
+
        return xdp_pkt;
 }
 
@@ -265,6 +252,31 @@ static struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu,
        return skb;
 }
 
+static void __cpu_map_ring_cleanup(struct ptr_ring *ring)
+{
+       /* The tear-down procedure should have made sure that queue is
+        * empty.  See __cpu_map_entry_replace() and work-queue
+        * invoked cpu_map_kthread_stop(). Catch any broken behaviour
+        * gracefully and warn once.
+        */
+       struct xdp_pkt *xdp_pkt;
+
+       while ((xdp_pkt = ptr_ring_consume(ring)))
+               if (WARN_ON_ONCE(xdp_pkt))
+                       xdp_return_frame(xdp_pkt, &xdp_pkt->mem);
+}
+
+static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu)
+{
+       if (atomic_dec_and_test(&rcpu->refcnt)) {
+               /* The queue should be empty at this point */
+               __cpu_map_ring_cleanup(rcpu->queue);
+               ptr_ring_cleanup(rcpu->queue, NULL);
+               kfree(rcpu->queue);
+               kfree(rcpu);
+       }
+}
+
 static int cpu_map_kthread_run(void *data)
 {
        struct bpf_cpu_map_entry *rcpu = data;
@@ -307,7 +319,7 @@ static int cpu_map_kthread_run(void *data)
 
                        skb = cpu_map_build_skb(rcpu, xdp_pkt);
                        if (!skb) {
-                               page_frag_free(xdp_pkt);
+                               xdp_return_frame(xdp_pkt, &xdp_pkt->mem);
                                continue;
                        }
 
@@ -604,13 +616,13 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
        spin_lock(&q->producer_lock);
 
        for (i = 0; i < bq->count; i++) {
-               void *xdp_pkt = bq->q[i];
+               struct xdp_pkt *xdp_pkt = bq->q[i];
                int err;
 
                err = __ptr_ring_produce(q, xdp_pkt);
                if (err) {
                        drops++;
-                       page_frag_free(xdp_pkt); /* Free xdp_pkt */
+                       xdp_return_frame(xdp_pkt->data, &xdp_pkt->mem);
                }
                processed++;
        }

diff --git a/net/core/xdp.c b/net/core/xdp.c
index 097a0f7..7e6b354 100644 (file)
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -71,3 +71,21 @@ bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
        return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
+
+int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
+                              enum xdp_mem_type type, void *allocator)
+{
+       if (type >= MEM_TYPE_MAX)
+               return -EINVAL;
+
+       xdp_rxq->mem.type = type;
+
+       if (allocator)
+               return -EOPNOTSUPP;
+
+       /* TODO: Allocate an ID that maps to allocator pointer
+        * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
+        */
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);