qeth: HiperSockets SIGA retry support on CC=2.

Qeth HiperSockets support now retries sending of packets when the
IBM System z signals a temporary resource shortage (e.g. target
buffer full). The packet is enqueued into the device queue.
After 3 times of unsuccessful send the packet is dropped.

Signed-off-by: Klaus-Dieter Wacker <kdwacker@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 61 insertions, 8 deletions

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index 447e1d19581a..03161e650b24 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -435,6 +435,7 @@ struct qeth_qdio_out_q {
          * index of buffer to be filled by driver; state EMPTY or PACKING
          */
         int next_buf_to_fill;
+        int sync_iqdio_error;
         /*
          * number of buffers that are currently filled (PRIMED)
          * -> these buffers are hardware-owned
@@ -685,6 +686,14 @@ struct qeth_mc_mac {
         int is_vmac;
 };
 
+struct qeth_skb_data {
+        __u32 magic;
+        int count;
+};
+
+#define QETH_SKB_MAGIC 0x71657468
+#define QETH_SIGA_CC2_RETRIES 3
+
 struct qeth_card {
         struct list_head list;
         enum qeth_card_states state;
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index d53621c4acbb..ac7270d21708 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -927,8 +927,8 @@ out:
         return;
 }
 
-static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
-                 struct qeth_qdio_out_buffer *buf)
+static void __qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
+                 struct qeth_qdio_out_buffer *buf, unsigned int qeth_skip_skb)
 {
         int i;
         struct sk_buff *skb;
@@ -937,11 +937,13 @@ static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
         if (buf->buffer->element[0].flags & 0x40)
                 atomic_dec(&queue->set_pci_flags_count);
 
-        skb = skb_dequeue(&buf->skb_list);
-        while (skb) {
-                atomic_dec(&skb->users);
-                dev_kfree_skb_any(skb);
+        if (!qeth_skip_skb) {
                 skb = skb_dequeue(&buf->skb_list);
+                while (skb) {
+                        atomic_dec(&skb->users);
+                        dev_kfree_skb_any(skb);
+                        skb = skb_dequeue(&buf->skb_list);
+                }
         }
         for (i = 0; i < QETH_MAX_BUFFER_ELEMENTS(queue->card); ++i) {
                 if (buf->buffer->element[i].addr && buf->is_header[i])
@@ -957,6 +959,12 @@ static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
         atomic_set(&buf->state, QETH_QDIO_BUF_EMPTY);
 }
 
+static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
+                struct qeth_qdio_out_buffer *buf)
+{
+        __qeth_clear_output_buffer(queue, buf, 0);
+}
+
 void qeth_clear_qdio_buffers(struct qeth_card *card)
 {
         int i, j;
@@ -2685,6 +2693,13 @@ static int qeth_handle_send_error(struct qeth_card *card,
         int sbalf15 = buffer->buffer->element[15].flags & 0xff;
 
         QETH_DBF_TEXT(TRACE, 6, "hdsnderr");
+        if (card->info.type == QETH_CARD_TYPE_IQD) {
+                if (sbalf15 == 0) {
+                        qdio_err = 0;
+                } else {
+                        qdio_err = 1;
+                }
+        }
         qeth_check_qdio_errors(buffer->buffer, qdio_err, "qouterr");
 
         if (!qdio_err)
@@ -2817,6 +2832,7 @@ static void qeth_flush_buffers(struct qeth_qdio_out_q *queue, int index,
                 }
         }
 
+        queue->sync_iqdio_error = 0;
         queue->card->dev->trans_start = jiffies;
         if (queue->card->options.performance_stats) {
                 queue->card->perf_stats.outbound_do_qdio_cnt++;
@@ -2832,6 +2848,10 @@ static void qeth_flush_buffers(struct qeth_qdio_out_q *queue, int index,
                 queue->card->perf_stats.outbound_do_qdio_time +=
                         qeth_get_micros() -
                         queue->card->perf_stats.outbound_do_qdio_start_time;
+        if (rc > 0) {
+                if (!(rc & QDIO_ERROR_SIGA_BUSY))
+                        queue->sync_iqdio_error = rc & 3;
+        }
         if (rc) {
                 queue->card->stats.tx_errors += count;
                 /* ignore temporary SIGA errors without busy condition */
@@ -2899,6 +2919,7 @@ void qeth_qdio_output_handler(struct ccw_device *ccwdev,
         struct qeth_qdio_out_q *queue = card->qdio.out_qs[__queue];
         struct qeth_qdio_out_buffer *buffer;
         int i;
+        unsigned qeth_send_err;
 
         QETH_DBF_TEXT(TRACE, 6, "qdouhdl");
         if (qdio_error & QDIO_ERROR_ACTIVATE_CHECK_CONDITION) {
@@ -2915,8 +2936,9 @@ void qeth_qdio_output_handler(struct ccw_device *ccwdev,
         }
         for (i = first_element; i < (first_element + count); ++i) {
                 buffer = &queue->bufs[i % QDIO_MAX_BUFFERS_PER_Q];
-                qeth_handle_send_error(card, buffer, qdio_error);
-                qeth_clear_output_buffer(queue, buffer);
+                qeth_send_err = qeth_handle_send_error(card, buffer, qdio_error);
+                __qeth_clear_output_buffer(queue, buffer,
+                        (qeth_send_err == QETH_SEND_ERROR_RETRY) ? 1 : 0);
         }
         atomic_sub(count, &queue->used_buffers);
         /* check if we need to do something on this outbound queue */
@@ -3159,7 +3181,10 @@ int qeth_do_send_packet_fast(struct qeth_card *card,
                 int offset, int hd_len)
 {
         struct qeth_qdio_out_buffer *buffer;
+        struct sk_buff *skb1;
+        struct qeth_skb_data *retry_ctrl;
         int index;
+        int rc;
 
         /* spin until we get the queue ... */
         while (atomic_cmpxchg(&queue->state, QETH_OUT_Q_UNLOCKED,
@@ -3178,6 +3203,25 @@ int qeth_do_send_packet_fast(struct qeth_card *card,
         atomic_set(&queue->state, QETH_OUT_Q_UNLOCKED);
         qeth_fill_buffer(queue, buffer, skb, hdr, offset, hd_len);
         qeth_flush_buffers(queue, index, 1);
+        if (queue->sync_iqdio_error == 2) {
+                skb1 = skb_dequeue(&buffer->skb_list);
+                while (skb1) {
+                        atomic_dec(&skb1->users);
+                        skb1 = skb_dequeue(&buffer->skb_list);
+                }
+                retry_ctrl = (struct qeth_skb_data *) &skb->cb[16];
+                if (retry_ctrl->magic != QETH_SKB_MAGIC) {
+                        retry_ctrl->magic = QETH_SKB_MAGIC;
+                        retry_ctrl->count = 0;
+                }
+                if (retry_ctrl->count < QETH_SIGA_CC2_RETRIES) {
+                        retry_ctrl->count++;
+                        rc = dev_queue_xmit(skb);
+                } else {
+                        dev_kfree_skb_any(skb);
+                        QETH_DBF_TEXT(QERR, 2, "qrdrop");
+                }
+        }
         return 0;
 out:
         atomic_set(&queue->state, QETH_OUT_Q_UNLOCKED);