[PATCH net-next 10/13] s390/qeth: consolidate skb allocation

Julian Wiedmann
2017-10-18T15:40:22Z

Move the allocation of SG skbs into the main path. This allows for
a little code sharing, and handling ENOMEM from within one place.

As side effect, L2 SG skbs now get the proper amount of additional
headroom (read: zero) instead of the hard-coded ETH_HLEN.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
---
drivers/s390/net/qeth_core_main.c | 71 +++++++++++++++++----------------------
1 file changed, 31 insertions(+), 40 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 1cf4e066955f..23b439fb5f2c 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -5170,41 +5170,27 @@ int qeth_core_hardsetup_card(struct qeth_card *card)
}
EXPORT_SYMBOL_GPL(qeth_core_hardsetup_card);

-static int qeth_create_skb_frag(struct qeth_qdio_buffer *qethbuffer,
- struct qdio_buffer_element *element,
- struct sk_buff **pskb, int offset, int data_len)
+static void qeth_create_skb_frag(struct qdio_buffer_element *element,
+ struct sk_buff *skb, int offset, int data_len)
{
struct page *page = virt_to_page(element->addr);
unsigned int next_frag;

- if (*pskb == NULL) {
- if (qethbuffer->rx_skb) {
- /* only if qeth_card.options.cq == QETH_CQ_ENABLED */
- *pskb = qethbuffer->rx_skb;
- qethbuffer->rx_skb = NULL;
- } else {
- *pskb = dev_alloc_skb(QETH_RX_PULL_LEN + ETH_HLEN);
- if (!(*pskb))
- return -ENOMEM;
- }
+ /* first fill the linear space */
+ if (!skb->len) {
+ unsigned int linear = min(data_len, skb_tailroom(skb));

- skb_reserve(*pskb, ETH_HLEN);
- if (data_len <= QETH_RX_PULL_LEN) {
- skb_put_data(*pskb, element->addr + offset, data_len);
- return 0;
- } else {
- skb_put_data(*pskb, element->addr + offset,
- QETH_RX_PULL_LEN);
- data_len -= QETH_RX_PULL_LEN;
- offset += QETH_RX_PULL_LEN;
- /* fall through to add page frag for remaining data */
- }
+ skb_put_data(skb, element->addr + offset, linear);
+ data_len -= linear;
+ if (!data_len)
+ return;
+ offset += linear;
+ /* fall through to add page frag for remaining data */
}

- next_frag = skb_shinfo(*pskb)->nr_frags;
+ next_frag = skb_shinfo(skb)->nr_frags;
get_page(page);
- skb_add_rx_frag(*pskb, next_frag, page, offset, data_len, data_len);
- return 0;
+ skb_add_rx_frag(skb, next_frag, page, offset, data_len, data_len);
}

static inline int qeth_is_last_sbale(struct qdio_buffer_element *sbale)
@@ -5220,7 +5206,7 @@ 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;
- struct sk_buff *skb = NULL;
+ struct sk_buff *skb;
int skb_len = 0;
void *data_ptr;
int data_len;
@@ -5261,27 +5247,32 @@ struct sk_buff *qeth_core_get_next_skb(struct qeth_card *card,
if (((skb_len >= card->options.rx_sg_cb) &&
(!(card->info.type == QETH_CARD_TYPE_OSN)) &&
(!atomic_read(&card->force_alloc_skb))) ||
- (card->options.cq == QETH_CQ_ENABLED)) {
+ (card->options.cq == QETH_CQ_ENABLED))
use_rx_sg = 1;
+
+ if (use_rx_sg && qethbuffer->rx_skb) {
+ /* QETH_CQ_ENABLED only: */
+ skb = qethbuffer->rx_skb;
+ qethbuffer->rx_skb = NULL;
} else {
- skb = dev_alloc_skb(skb_len + headroom);
- if (!skb)
- goto no_mem;
- if (headroom)
- skb_reserve(skb, headroom);
+ unsigned int linear = (use_rx_sg) ? QETH_RX_PULL_LEN : skb_len;
+
+ skb = dev_alloc_skb(linear + headroom);
}
+ if (!skb)
+ goto no_mem;
+ if (headroom)
+ skb_reserve(skb, headroom);

data_ptr = element->addr + offset;
while (skb_len) {
data_len = min(skb_len, (int)(element->length - offset));
if (data_len) {
- if (use_rx_sg) {
- if (qeth_create_skb_frag(qethbuffer, element,
- &skb, offset, data_len))
- goto no_mem;
- } else {
+ if (use_rx_sg)
+ qeth_create_skb_frag(element, skb, offset,
+ data_len);
+ else
skb_put_data(skb, data_ptr, data_len);
- }
}
skb_len -= data_len;
if (skb_len) {
--
2.13.5