af_iucv: use paged SKBs for big inbound messages

When an inbound message is bigger than a page, allocate a paged SKB,
and subsequently use IUCV receive primitive with IPBUFLST flag.
This relaxes the pressure to allocate big contiguous kernel buffers.

Signed-off-by: Eugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 9ed2adf9e057b3ff5840990fe7a141254f3c3163..37d674e6f8a9f4f1e8bc31ea49ed8a4f1333241f 100644 (file)
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1231,6 +1231,34 @@ out:
        return err;
 }
 
+static struct sk_buff *alloc_iucv_recv_skb(unsigned long len)
+{
+       size_t headroom, linear;
+       struct sk_buff *skb;
+       int err;
+
+       if (len < PAGE_SIZE) {
+               headroom = 0;
+               linear = len;
+       } else {
+               headroom = sizeof(struct iucv_array) * (MAX_SKB_FRAGS + 1);
+               linear = PAGE_SIZE - headroom;
+       }
+       skb = alloc_skb_with_frags(headroom + linear, len - linear,
+                                  0, &err, GFP_ATOMIC | GFP_DMA);
+       WARN_ONCE(!skb,
+                 "alloc of recv iucv skb len=%lu failed with errcode=%d\n",
+                 len, err);
+       if (skb) {
+               if (headroom)
+                       skb_reserve(skb, headroom);
+               skb_put(skb, linear);
+               skb->len = len;
+               skb->data_len = len - linear;
+       }
+       return skb;
+}
+
 /* iucv_process_message() - Receive a single outstanding IUCV message
  *
  * Locking: must be called with message_q.lock held
@@ -1255,16 +1283,32 @@ static void iucv_process_message(struct sock *sk, struct sk_buff *skb,
                        skb->len = 0;
                }
        } else {
-               rc = pr_iucv->message_receive(path, msg,
+               if (skb_is_nonlinear(skb)) {
+                       struct iucv_array *iba = (struct iucv_array *)skb->head;
+                       int i;
+
+                       iba[0].address = (u32)(addr_t)skb->data;
+                       iba[0].length = (u32)skb_headlen(skb);
+                       for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+                               skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+                               iba[i + 1].address =
+                                       (u32)(addr_t)skb_frag_address(frag);
+                               iba[i + 1].length = (u32)skb_frag_size(frag);
+                       }
+                       rc = pr_iucv->message_receive(path, msg,
+                                             IUCV_IPBUFLST,
+                                             (void *)iba, len, NULL);
+               } else {
+                       rc = pr_iucv->message_receive(path, msg,
                                              msg->flags & IUCV_IPRMDATA,
                                              skb->data, len, NULL);
+               }
                if (rc) {
                        kfree_skb(skb);
                        return;
                }
-               skb_reset_transport_header(skb);
-               skb_reset_network_header(skb);
-               skb->len = len;
+               WARN_ON_ONCE(skb->len != len);
        }
 
        IUCV_SKB_CB(skb)->offset = 0;
@@ -1283,7 +1327,7 @@ static void iucv_process_message_q(struct sock *sk)
        struct sock_msg_q *p, *n;
 
        list_for_each_entry_safe(p, n, &iucv->message_q.list, list) {
-               skb = alloc_skb(iucv_msg_length(&p->msg), GFP_ATOMIC | GFP_DMA);
+               skb = alloc_iucv_recv_skb(iucv_msg_length(&p->msg));
                if (!skb)
                        break;
                iucv_process_message(sk, skb, p->path, &p->msg);
@@ -1778,7 +1822,7 @@ static void iucv_callback_rx(struct iucv_path *path, struct iucv_message *msg)
        if (len > sk->sk_rcvbuf)
                goto save_message;
 
-       skb = alloc_skb(iucv_msg_length(msg), GFP_ATOMIC | GFP_DMA);
+       skb = alloc_iucv_recv_skb(iucv_msg_length(msg));
        if (!skb)
                goto save_message;