[SCSI] cxgb3i: fix cpu use abuse during writes

When doing a lot (128) of large writes (256K) we can hit the cxgb3_snd_win
check pretty easily. The driver's xmit thread then takes 100% of the cpu.

The driver should not be returning -EAGAIN for this problem. It should
be returing -ENOBUFS, then when the window is opened again it should
queue the xmit thread (it already wakes the xmit thread).

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 13 insertions, 10 deletions

diff --git a/drivers/scsi/cxgb3i/cxgb3i_offload.c b/drivers/scsi/cxgb3i/cxgb3i_offload.c
index 4d8654cdbdae..e11c9c180f39 100644
--- a/drivers/scsi/cxgb3i/cxgb3i_offload.c
+++ b/drivers/scsi/cxgb3i/cxgb3i_offload.c
@@ -1737,7 +1737,7 @@ int cxgb3i_c3cn_send_pdus(struct s3_conn *c3cn, struct sk_buff *skb)
                 c3cn_tx_debug("c3cn 0x%p, snd %u - %u > %u.\n",
                                 c3cn, c3cn->write_seq, c3cn->snd_una,
                                 cxgb3_snd_win);
-                err = -EAGAIN;
+                err = -ENOBUFS;
                 goto out_err;
         }
 
@@ -1775,6 +1775,8 @@ done:
 out_err:
         if (copied == 0 && err == -EPIPE)
                 copied = c3cn->err ? c3cn->err : -EPIPE;
+        else
+                copied = err;
         goto done;
 }
 
diff --git a/drivers/scsi/cxgb3i/cxgb3i_pdu.c b/drivers/scsi/cxgb3i/cxgb3i_pdu.c
index 7eebc9a7cb35..709105071177 100644
--- a/drivers/scsi/cxgb3i/cxgb3i_pdu.c
+++ b/drivers/scsi/cxgb3i/cxgb3i_pdu.c
@@ -400,17 +400,18 @@ int cxgb3i_conn_xmit_pdu(struct iscsi_task *task)
                 return 0;
         }
 
-        if (err < 0 && err != -EAGAIN) {
-                kfree_skb(skb);
-                cxgb3i_tx_debug("itt 0x%x, skb 0x%p, len %u/%u, xmit err %d.\n",
-                                task->itt, skb, skb->len, skb->data_len, err);
-                iscsi_conn_printk(KERN_ERR, task->conn, "xmit err %d.\n", err);
-                iscsi_conn_failure(task->conn, ISCSI_ERR_XMIT_FAILED);
+        if (err == -EAGAIN || err == -ENOBUFS) {
+                /* reset skb to send when we are called again */
+                tdata->skb = skb;
                 return err;
         }
-        /* reset skb to send when we are called again */
-        tdata->skb = skb;
-        return -EAGAIN;
+
+        kfree_skb(skb);
+        cxgb3i_tx_debug("itt 0x%x, skb 0x%p, len %u/%u, xmit err %d.\n",
+                        task->itt, skb, skb->len, skb->data_len, err);
+        iscsi_conn_printk(KERN_ERR, task->conn, "xmit err %d.\n", err);
+        iscsi_conn_failure(task->conn, ISCSI_ERR_XMIT_FAILED);
+        return err;
 }
 
 int cxgb3i_pdu_init(void)