iser-target: Add missing se_cmd put for WRITE_PENDING in tx_comp_err

This patch fixes a bug where outstanding RDMA_READs with WRITE_PENDING
status require an extra target_put_sess_cmd() in isert_put_cmd() code
when called from isert_cq_tx_comp_err() + isert_cq_drain_comp_llist()
context during session shutdown.

The extra kref PUT is required so that transport_generic_free_cmd()
invokes the last target_put_sess_cmd() -> target_release_cmd_kref(),
which will complete(&se_cmd->cmd_wait_comp) the outstanding se_cmd
descriptor with WRITE_PENDING status, and awake the completion in
target_wait_for_sess_cmds() to invoke TFO->release_cmd().

The bug was manifesting itself in target_wait_for_sess_cmds() where
a se_cmd descriptor with WRITE_PENDING status would end up sleeping
indefinately.

Acked-by: Sagi Grimberg <sagig@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: <stable@vger.kernel.org> #3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 26 insertions, 11 deletions

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 18ada7fb0fc9..f7801aeb7628 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -1580,7 +1580,7 @@ isert_unreg_rdma(struct isert_cmd *isert_cmd, struct isert_conn *isert_conn)
 }
 
 static void
-isert_put_cmd(struct isert_cmd *isert_cmd)
+isert_put_cmd(struct isert_cmd *isert_cmd, bool comp_err)
 {
         struct iscsi_cmd *cmd = isert_cmd->iscsi_cmd;
         struct isert_conn *isert_conn = isert_cmd->conn;
@@ -1596,8 +1596,21 @@ isert_put_cmd(struct isert_cmd *isert_cmd)
                         list_del_init(&cmd->i_conn_node);
                 spin_unlock_bh(&conn->cmd_lock);
 
-                if (cmd->data_direction == DMA_TO_DEVICE)
+                if (cmd->data_direction == DMA_TO_DEVICE) {
                         iscsit_stop_dataout_timer(cmd);
+                        /*
+                         * Check for special case during comp_err where
+                         * WRITE_PENDING has been handed off from core,
+                         * but requires an extra target_put_sess_cmd()
+                         * before transport_generic_free_cmd() below.
+                         */
+                        if (comp_err &&
+                            cmd->se_cmd.t_state == TRANSPORT_WRITE_PENDING) {
+                                struct se_cmd *se_cmd = &cmd->se_cmd;
+
+                                target_put_sess_cmd(se_cmd->se_sess, se_cmd);
+                        }
+                }
 
                 device->unreg_rdma_mem(isert_cmd, isert_conn);
                 transport_generic_free_cmd(&cmd->se_cmd, 0);
@@ -1652,7 +1665,7 @@ isert_unmap_tx_desc(struct iser_tx_desc *tx_desc, struct ib_device *ib_dev)
 
 static void
 isert_completion_put(struct iser_tx_desc *tx_desc, struct isert_cmd *isert_cmd,
-                     struct ib_device *ib_dev)
+                     struct ib_device *ib_dev, bool comp_err)
 {
         if (isert_cmd->pdu_buf_dma != 0) {
                 pr_debug("Calling ib_dma_unmap_single for isert_cmd->pdu_buf_dma\n");
@@ -1662,7 +1675,7 @@ isert_completion_put(struct iser_tx_desc *tx_desc, struct isert_cmd *isert_cmd,
         }
 
         isert_unmap_tx_desc(tx_desc, ib_dev);
-        isert_put_cmd(isert_cmd);
+        isert_put_cmd(isert_cmd, comp_err);
 }
 
 static int
@@ -1787,14 +1800,14 @@ isert_do_control_comp(struct work_struct *work)
                 iscsit_tmr_post_handler(cmd, cmd->conn);
 
                 cmd->i_state = ISTATE_SENT_STATUS;
-                isert_completion_put(&isert_cmd->tx_desc, isert_cmd, ib_dev);
+                isert_completion_put(&isert_cmd->tx_desc, isert_cmd, ib_dev, false);
                 break;
         case ISTATE_SEND_REJECT:
                 pr_debug("Got isert_do_control_comp ISTATE_SEND_REJECT: >>>\n");
                 atomic_dec(&isert_conn->post_send_buf_count);
 
                 cmd->i_state = ISTATE_SENT_STATUS;
-                isert_completion_put(&isert_cmd->tx_desc, isert_cmd, ib_dev);
+                isert_completion_put(&isert_cmd->tx_desc, isert_cmd, ib_dev, false);
                 break;
         case ISTATE_SEND_LOGOUTRSP:
                 pr_debug("Calling iscsit_logout_post_handler >>>>>>>>>>>>>>\n");
@@ -1808,7 +1821,7 @@ isert_do_control_comp(struct work_struct *work)
         case ISTATE_SEND_TEXTRSP:
                 atomic_dec(&isert_conn->post_send_buf_count);
                 cmd->i_state = ISTATE_SENT_STATUS;
-                isert_completion_put(&isert_cmd->tx_desc, isert_cmd, ib_dev);
+                isert_completion_put(&isert_cmd->tx_desc, isert_cmd, ib_dev, false);
                 break;
         default:
                 pr_err("Unknown do_control_comp i_state %d\n", cmd->i_state);
@@ -1850,7 +1863,7 @@ isert_response_completion(struct iser_tx_desc *tx_desc,
                 atomic_dec(&isert_conn->post_send_buf_count);
 
         cmd->i_state = ISTATE_SENT_STATUS;
-        isert_completion_put(tx_desc, isert_cmd, ib_dev);
+        isert_completion_put(tx_desc, isert_cmd, ib_dev, false);
 }
 
 static void
@@ -1943,7 +1956,8 @@ isert_cq_drain_comp_llist(struct isert_conn *isert_conn, struct ib_device *ib_de
                                    &isert_conn->post_send_buf_count);
                 else
                         atomic_dec(&isert_conn->post_send_buf_count);
-                isert_completion_put(t, t->isert_cmd, ib_dev);
+
+                isert_completion_put(t, t->isert_cmd, ib_dev, true);
         }
 }
 
@@ -1973,14 +1987,15 @@ isert_cq_tx_comp_err(struct iser_tx_desc *tx_desc, struct isert_conn *isert_conn
                                    &isert_conn->post_send_buf_count);
                 else
                         atomic_dec(&isert_conn->post_send_buf_count);
-                isert_completion_put(t, t->isert_cmd, ib_dev);
+
+                isert_completion_put(t, t->isert_cmd, ib_dev, true);
         }
         tx_desc->comp_llnode_batch = NULL;
 
         if (!isert_cmd)
                 isert_unmap_tx_desc(tx_desc, ib_dev);
         else
-                isert_completion_put(tx_desc, isert_cmd, ib_dev);
+                isert_completion_put(tx_desc, isert_cmd, ib_dev, true);
 }
 
 static void