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>

6 files changed, 25 insertions, 50 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);
diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index b03ee2ff31e5..f2094d2f8eef 100644
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -651,14 +651,13 @@ struct iscsi_session {
         /* Used for session reference counting */
         int                     session_usage_count;
         int                     session_waiting_on_uc;
-        u32                     cmd_pdus;
-        u32                     rsp_pdus;
-        u64                     tx_data_octets;
-        u64                     rx_data_octets;
-        u32                     conn_digest_errors;
-        u32                     conn_timeout_errors;
+        atomic_long_t           cmd_pdus;
+        atomic_long_t           rsp_pdus;
+        atomic_long_t           tx_data_octets;
+        atomic_long_t           rx_data_octets;
+        atomic_long_t           conn_digest_errors;
+        atomic_long_t           conn_timeout_errors;
         u64                     creation_time;
-        spinlock_t              session_stats_lock;
         /* Number of active connections */
         atomic_t                nconn;
         atomic_t                session_continuation;
diff --git a/drivers/target/iscsi/iscsi_target_erl0.c b/drivers/target/iscsi/iscsi_target_erl0.c
index cbea7f16d625..0d1e6ee3e992 100644
--- a/drivers/target/iscsi/iscsi_target_erl0.c
+++ b/drivers/target/iscsi/iscsi_target_erl0.c
@@ -785,7 +785,7 @@ static void iscsit_handle_time2retain_timeout(unsigned long data)
                 tiqn->sess_err_stats.last_sess_failure_type =
                                 ISCSI_SESS_ERR_CXN_TIMEOUT;
                 tiqn->sess_err_stats.cxn_timeout_errors++;
-                sess->conn_timeout_errors++;
+                atomic_long_inc(&sess->conn_timeout_errors);
                 spin_unlock(&tiqn->sess_err_stats.lock);
         }
         }
diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 646632aa2002..4eb93b2b6473 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -305,7 +305,6 @@ static int iscsi_login_zero_tsih_s1(
         }
 
         sess->creation_time = get_jiffies_64();
-        spin_lock_init(&sess->session_stats_lock);
         /*
          * The FFP CmdSN window values will be allocated from the TPG's
          * Initiator Node's ACL once the login has been successfully completed.
diff --git a/drivers/target/iscsi/iscsi_target_stat.c b/drivers/target/iscsi/iscsi_target_stat.c
index f788e8b5e855..103395510307 100644
--- a/drivers/target/iscsi/iscsi_target_stat.c
+++ b/drivers/target/iscsi/iscsi_target_stat.c
@@ -792,7 +792,8 @@ static ssize_t iscsi_stat_sess_show_attr_cmd_pdus(
         if (se_sess) {
                 sess = se_sess->fabric_sess_ptr;
                 if (sess)
-                        ret = snprintf(page, PAGE_SIZE, "%u\n", sess->cmd_pdus);
+                        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                                       atomic_long_read(&sess->cmd_pdus));
         }
         spin_unlock_bh(&se_nacl->nacl_sess_lock);
 
@@ -815,7 +816,8 @@ static ssize_t iscsi_stat_sess_show_attr_rsp_pdus(
         if (se_sess) {
                 sess = se_sess->fabric_sess_ptr;
                 if (sess)
-                        ret = snprintf(page, PAGE_SIZE, "%u\n", sess->rsp_pdus);
+                        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                                       atomic_long_read(&sess->rsp_pdus));
         }
         spin_unlock_bh(&se_nacl->nacl_sess_lock);
 
@@ -838,8 +840,8 @@ static ssize_t iscsi_stat_sess_show_attr_txdata_octs(
         if (se_sess) {
                 sess = se_sess->fabric_sess_ptr;
                 if (sess)
-                        ret = snprintf(page, PAGE_SIZE, "%llu\n",
-                                (unsigned long long)sess->tx_data_octets);
+                        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                                       atomic_long_read(&sess->tx_data_octets));
         }
         spin_unlock_bh(&se_nacl->nacl_sess_lock);
 
@@ -862,8 +864,8 @@ static ssize_t iscsi_stat_sess_show_attr_rxdata_octs(
         if (se_sess) {
                 sess = se_sess->fabric_sess_ptr;
                 if (sess)
-                        ret = snprintf(page, PAGE_SIZE, "%llu\n",
-                                (unsigned long long)sess->rx_data_octets);
+                        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                                       atomic_long_read(&sess->rx_data_octets));
         }
         spin_unlock_bh(&se_nacl->nacl_sess_lock);
 
@@ -886,8 +888,8 @@ static ssize_t iscsi_stat_sess_show_attr_conn_digest_errors(
         if (se_sess) {
                 sess = se_sess->fabric_sess_ptr;
                 if (sess)
-                        ret = snprintf(page, PAGE_SIZE, "%u\n",
-                                        sess->conn_digest_errors);
+                        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                                       atomic_long_read(&sess->conn_digest_errors));
         }
         spin_unlock_bh(&se_nacl->nacl_sess_lock);
 
@@ -910,8 +912,8 @@ static ssize_t iscsi_stat_sess_show_attr_conn_timeout_errors(
         if (se_sess) {
                 sess = se_sess->fabric_sess_ptr;
                 if (sess)
-                        ret = snprintf(page, PAGE_SIZE, "%u\n",
-                                        sess->conn_timeout_errors);
+                        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                                       atomic_long_read(&sess->conn_timeout_errors));
         }
         spin_unlock_bh(&se_nacl->nacl_sess_lock);
 
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index f2de28e178fd..45b8fd13fa72 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -980,7 +980,7 @@ static void iscsit_handle_nopin_response_timeout(unsigned long data)
                 tiqn->sess_err_stats.last_sess_failure_type =
                                 ISCSI_SESS_ERR_CXN_TIMEOUT;
                 tiqn->sess_err_stats.cxn_timeout_errors++;
-                conn->sess->conn_timeout_errors++;
+                atomic_long_inc(&conn->sess->conn_timeout_errors);
                 spin_unlock_bh(&tiqn->sess_err_stats.lock);
         }
         }