s390/qeth: handle skb allocation error gracefully

When current code fails to allocate an skb in the RX path, it drops the
whole RX buffer. Considering the large number of packets that a single
RX buffer might contain, this is quite drastic.

Skip over the packet instead, and try to extract the next packet from
the RX buffer.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 467a917..08185f7 100644 (file)
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -5065,12 +5065,12 @@ struct sk_buff *qeth_core_get_next_skb(struct qeth_card *card,
        struct qdio_buffer_element *element = *__element;
        struct qdio_buffer *buffer = qethbuffer->buffer;
        int offset = *__offset;
+       bool use_rx_sg = false;
+       unsigned int headroom;
        struct sk_buff *skb;
        int skb_len = 0;
        void *data_ptr;
        int data_len;
-       int headroom = 0;
-       int use_rx_sg = 0;
 
 next_packet:
        /* qeth_hdr must not cross element boundaries */
@@ -5086,6 +5086,7 @@ next_packet:
        switch ((*hdr)->hdr.l2.id) {
        case QETH_HEADER_TYPE_LAYER2:
                skb_len = (*hdr)->hdr.l2.pkt_length;
+               headroom = 0;
                break;
        case QETH_HEADER_TYPE_LAYER3:
                skb_len = (*hdr)->hdr.l3.length;
@@ -5120,11 +5121,10 @@ next_packet:
        if (!skb_len)
                return NULL;
 
-       if (((skb_len >= card->options.rx_sg_cb) &&
-            !IS_OSN(card) &&
-            (!atomic_read(&card->force_alloc_skb))) ||
-           (card->options.cq == QETH_CQ_ENABLED))
-               use_rx_sg = 1;
+       use_rx_sg = (card->options.cq == QETH_CQ_ENABLED) ||
+                   ((skb_len >= card->options.rx_sg_cb) &&
+                    !atomic_read(&card->force_alloc_skb) &&
+                    !IS_OSN(card));
 
        if (use_rx_sg && qethbuffer->rx_skb) {
                /* QETH_CQ_ENABLED only: */
@@ -5135,9 +5135,10 @@ next_packet:
 
                skb = napi_alloc_skb(&card->napi, linear + headroom);
        }
+
        if (!skb)
-               goto no_mem;
-       if (headroom)
+               QETH_CARD_STAT_INC(card, rx_dropped_nomem);
+       else if (headroom)
                skb_reserve(skb, headroom);
 
 walk_packet:
@@ -5184,12 +5185,6 @@ walk_packet:
                                   skb_shinfo(skb)->nr_frags);
        }
        return skb;
-no_mem:
-       if (net_ratelimit()) {
-               QETH_CARD_TEXT(card, 2, "noskbmem");
-       }
-       QETH_CARD_STAT_INC(card, rx_dropped_nomem);
-       return NULL;
 }
 EXPORT_SYMBOL_GPL(qeth_core_get_next_skb);