IB/iser: Return error code when PDUs may not be sent

iSER limits the number of outstanding PDUs to send. When this threshold
is reached, it should return an error code (-ENOBUFS) instead of setting
the suspend_tx bit (which should be used only by libiscsi).

Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 14 insertions, 16 deletions

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 9b2041e25d59..dd221eda3ea6 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -177,7 +177,7 @@ iscsi_iser_mtask_xmit(struct iscsi_conn *conn,
          * - if yes, the mtask is recycled at iscsi_complete_pdu
          * - if no,  the mtask is recycled at iser_snd_completion
          */
-        if (error && error != -EAGAIN)
+        if (error && error != -ENOBUFS)
                 iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
 
         return error;
@@ -241,7 +241,7 @@ iscsi_iser_ctask_xmit(struct iscsi_conn *conn,
                 error = iscsi_iser_ctask_xmit_unsol_data(conn, ctask);
 
  iscsi_iser_ctask_xmit_exit:
-        if (error && error != -EAGAIN)
+        if (error && error != -ENOBUFS)
                 iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
         return error;
 }
diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
index e73c87b9be43..0a7d1ab60e6d 100644
--- a/drivers/infiniband/ulp/iser/iser_initiator.c
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -304,18 +304,14 @@ int iser_conn_set_full_featured_mode(struct iscsi_conn *conn)
 static int
 iser_check_xmit(struct iscsi_conn *conn, void *task)
 {
-        int rc = 0;
         struct iscsi_iser_conn *iser_conn = conn->dd_data;
 
-        write_lock_bh(conn->recv_lock);
         if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
             ISER_QP_MAX_REQ_DTOS) {
-                iser_dbg("%ld can't xmit task %p, suspending tx\n",jiffies,task);
-                set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
-                rc = -EAGAIN;
+                iser_dbg("%ld can't xmit task %p\n",jiffies,task);
+                return -ENOBUFS;
         }
-        write_unlock_bh(conn->recv_lock);
-        return rc;
+        return 0;
 }
 
 
@@ -340,7 +336,7 @@ int iser_send_command(struct iscsi_conn     *conn,
                 return -EPERM;
         }
         if (iser_check_xmit(conn, ctask))
-                return -EAGAIN;
+                return -ENOBUFS;
 
         edtl = ntohl(hdr->data_length);
 
@@ -426,7 +422,7 @@ int iser_send_data_out(struct iscsi_conn     *conn,
         }
 
         if (iser_check_xmit(conn, ctask))
-                return -EAGAIN;
+                return -ENOBUFS;
 
         itt = ntohl(hdr->itt);
         data_seg_len = ntoh24(hdr->dlength);
@@ -498,7 +494,7 @@ int iser_send_control(struct iscsi_conn *conn,
         }
 
         if (iser_check_xmit(conn,mtask))
-                return -EAGAIN;
+                return -ENOBUFS;
 
         /* build the tx desc regd header and add it to the tx desc dto */
         mdesc->type = ISCSI_TX_CONTROL;
@@ -605,6 +601,7 @@ void iser_snd_completion(struct iser_desc *tx_desc)
         struct iscsi_iser_conn *iser_conn = ib_conn->iser_conn;
         struct iscsi_conn      *conn = iser_conn->iscsi_conn;
         struct iscsi_mgmt_task *mtask;
+        int resume_tx = 0;
 
         iser_dbg("Initiator, Data sent dto=0x%p\n", dto);
 
@@ -613,15 +610,16 @@ void iser_snd_completion(struct iser_desc *tx_desc)
         if (tx_desc->type == ISCSI_TX_DATAOUT)
                 kmem_cache_free(ig.desc_cache, tx_desc);
 
+        if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
+            ISER_QP_MAX_REQ_DTOS)
+                resume_tx = 1;
+
         atomic_dec(&ib_conn->post_send_buf_count);
 
-        write_lock(conn->recv_lock);
-        if (conn->suspend_tx) {
+        if (resume_tx) {
                 iser_dbg("%ld resuming tx\n",jiffies);
-                clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
                 scsi_queue_work(conn->session->host, &conn->xmitwork);
         }
-        write_unlock(conn->recv_lock);
 
         if (tx_desc->type == ISCSI_TX_CONTROL) {
                 /* this arithmetic is legal by libiscsi dd_data allocation */