tcm_fc: Generate TASK_SET_FULL status for response failures

This patch changes ft_queue_status() to set SAM_STAT_TASK_SET_FULL
status upon lport->tt.seq_send( failure, and return -EAGAIN to notify
target-core to attempt to requeue the response.

It also does the same for a fc_frame_alloc() failures, in order to
signal the initiator that it should try to reduce it's current
queue_depth, to lower the number of outstanding I/Os on the wire.

Reported-by: Vasu Dev <vasu.dev@linux.intel.com>
Reviewed-by: Vasu Dev <vasu.dev@linux.intel.com>
Cc: Jun Wu <jwu@stormojo.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/tcm_fc/tfc_cmd.c b/drivers/target/tcm_fc/tfc_cmd.c
index f5fd515b2bee266dd9c8279ea804bc7372d955f3..be0c0d08c56a91ff9acc97e8db92868c39c25f0c 100644 (file)
--- a/drivers/target/tcm_fc/tfc_cmd.c
+++ b/drivers/target/tcm_fc/tfc_cmd.c
@@ -128,6 +128,7 @@ int ft_queue_status(struct se_cmd *se_cmd)
        struct fc_lport *lport;
        struct fc_exch *ep;
        size_t len;
+       int rc;
 
        if (cmd->aborted)
                return 0;
@@ -137,9 +138,10 @@ int ft_queue_status(struct se_cmd *se_cmd)
        len = sizeof(*fcp) + se_cmd->scsi_sense_length;
        fp = fc_frame_alloc(lport, len);
        if (!fp) {
-               /* XXX shouldn't just drop it - requeue and retry? */
-               return 0;
+               se_cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
+               return -ENOMEM;
        }
+
        fcp = fc_frame_payload_get(fp, len);
        memset(fcp, 0, len);
        fcp->resp.fr_status = se_cmd->scsi_status;
@@ -170,7 +172,18 @@ int ft_queue_status(struct se_cmd *se_cmd)
        fc_fill_fc_hdr(fp, FC_RCTL_DD_CMD_STATUS, ep->did, ep->sid, FC_TYPE_FCP,
                       FC_FC_EX_CTX | FC_FC_LAST_SEQ | FC_FC_END_SEQ, 0);
 
-       lport->tt.seq_send(lport, cmd->seq, fp);
+       rc = lport->tt.seq_send(lport, cmd->seq, fp);
+       if (rc) {
+               pr_info_ratelimited("%s: Failed to send response frame %p, "
+                                   "xid <0x%x>\n", __func__, fp, ep->xid);
+               /*
+                * Generate a TASK_SET_FULL status to notify the initiator
+                * to reduce it's queue_depth after the se_cmd response has
+                * been re-queued by target-core.
+                */
+               se_cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
+               return -ENOMEM;
+       }
        lport->tt.exch_done(cmd->seq);
        return 0;
 }