iscsi-target: Convert iscsi_session statistics to atomic_long_t

This patch converts a handful of iscsi_session statistics to type
atomic_long_t, instead of using iscsi_session->session_stats_lock
when incrementing these values.

More importantly, go ahead and drop the spinlock usage within
iscsit_setup_scsi_cmd(), iscsit_check_dataout_hdr(),
iscsit_send_datain(), and iscsit_build_rsp_pdu() fast-path code.

(Squash in Roland's  target: Remove write-only stats fields and lock
from struct se_node_acl)

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 5 insertions, 30 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index ba9787d24c12..bf76fc46fc52 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -800,14 +800,7 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
         int iscsi_task_attr;
         int sam_task_attr;
 
-        spin_lock_bh(&conn->sess->session_stats_lock);
-        conn->sess->cmd_pdus++;
-        if (conn->sess->se_sess->se_node_acl) {
-                spin_lock(&conn->sess->se_sess->se_node_acl->stats_lock);
-                conn->sess->se_sess->se_node_acl->num_cmds++;
-                spin_unlock(&conn->sess->se_sess->se_node_acl->stats_lock);
-        }
-        spin_unlock_bh(&conn->sess->session_stats_lock);
+        atomic_long_inc(&conn->sess->cmd_pdus);
 
         hdr                     = (struct iscsi_scsi_req *) buf;
         payload_length          = ntoh24(hdr->dlength);
@@ -1254,14 +1247,7 @@ iscsit_check_dataout_hdr(struct iscsi_conn *conn, unsigned char *buf,
         }
 
         /* iSCSI write */
-        spin_lock_bh(&conn->sess->session_stats_lock);
-        conn->sess->rx_data_octets += payload_length;
-        if (conn->sess->se_sess->se_node_acl) {
-                spin_lock(&conn->sess->se_sess->se_node_acl->stats_lock);
-                conn->sess->se_sess->se_node_acl->write_bytes += payload_length;
-                spin_unlock(&conn->sess->se_sess->se_node_acl->stats_lock);
-        }
-        spin_unlock_bh(&conn->sess->session_stats_lock);
+        atomic_long_add(payload_length, &conn->sess->rx_data_octets);
 
         if (payload_length > conn->conn_ops->MaxXmitDataSegmentLength) {
                 pr_err("DataSegmentLength: %u is greater than"
@@ -2631,14 +2617,7 @@ static int iscsit_send_datain(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
                 return -1;
         }
 
-        spin_lock_bh(&conn->sess->session_stats_lock);
-        conn->sess->tx_data_octets += datain.length;
-        if (conn->sess->se_sess->se_node_acl) {
-                spin_lock(&conn->sess->se_sess->se_node_acl->stats_lock);
-                conn->sess->se_sess->se_node_acl->read_bytes += datain.length;
-                spin_unlock(&conn->sess->se_sess->se_node_acl->stats_lock);
-        }
-        spin_unlock_bh(&conn->sess->session_stats_lock);
+        atomic_long_add(datain.length, &conn->sess->tx_data_octets);
         /*
          * Special case for successfully execution w/ both DATAIN
          * and Sense Data.
@@ -3163,9 +3142,7 @@ void iscsit_build_rsp_pdu(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
         if (inc_stat_sn)
                 cmd->stat_sn = conn->stat_sn++;
 
-        spin_lock_bh(&conn->sess->session_stats_lock);
-        conn->sess->rsp_pdus++;
-        spin_unlock_bh(&conn->sess->session_stats_lock);
+        atomic_long_inc(&conn->sess->rsp_pdus);
 
         memset(hdr, 0, ISCSI_HDR_LEN);
         hdr->opcode             = ISCSI_OP_SCSI_CMD_RSP;
@@ -4114,9 +4091,7 @@ restart:
                                  * hit default in the switch below.
                                  */
                                 memset(buffer, 0xff, ISCSI_HDR_LEN);
-                                spin_lock_bh(&conn->sess->session_stats_lock);
-                                conn->sess->conn_digest_errors++;
-                                spin_unlock_bh(&conn->sess->session_stats_lock);
+                                atomic_long_inc(&conn->sess->conn_digest_errors);
                         } else {
                                 pr_debug("Got HeaderDigest CRC32C"
                                                 " 0x%08x\n", checksum);