target: Drop iSCSI use of mutex around max_cmd_sn increment

In a performance profile, taking a mutex in iscsit_increment_maxcmdsn()
shows up very high.  However taking a mutex around "sess->max_cmd_sn += 1"
seems pretty silly: we're not serializing against other contexts in
any useful way.

I did a quick audit and there don't appear to be any other places that
use max_cmd_sn within the mutex more than once, so this lock can't be
providing any useful serialization.

(Get correct values for logging - fix whitespace damage)

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Spencer Baugh <sbaugh@catern.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 986518c3ea12..e55f49c7c847 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -2555,7 +2555,7 @@ static int iscsit_send_conn_drop_async_message(
 	cmd->stat_sn		= conn->stat_sn++;
 	hdr->statsn		= cpu_to_be32(cmd->stat_sn);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 	hdr->async_event	= ISCSI_ASYNC_MSG_DROPPING_CONNECTION;
 	hdr->param1		= cpu_to_be16(cmd->logout_cid);
 	hdr->param2		= cpu_to_be16(conn->sess->sess_ops->DefaultTime2Wait);
@@ -2627,7 +2627,7 @@ iscsit_build_datain_pdu(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 		hdr->statsn		= cpu_to_be32(0xFFFFFFFF);
 
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 	hdr->datasn		= cpu_to_be32(datain->data_sn);
 	hdr->offset		= cpu_to_be32(datain->offset);
 
@@ -2838,7 +2838,7 @@ iscsit_build_logout_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 
 	iscsit_increment_maxcmdsn(cmd, conn->sess);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 
 	pr_debug("Built Logout Response ITT: 0x%08x StatSN:"
 		" 0x%08x Response: 0x%02x CID: %hu on CID: %hu\n",
@@ -2901,7 +2901,7 @@ iscsit_build_nopin_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 		iscsit_increment_maxcmdsn(cmd, conn->sess);
 
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 
 	pr_debug("Built NOPIN %s Response ITT: 0x%08x, TTT: 0x%08x,"
 		" StatSN: 0x%08x, Length %u\n", (nopout_response) ?
@@ -3048,7 +3048,7 @@ static int iscsit_send_r2t(
 	hdr->ttt		= cpu_to_be32(r2t->targ_xfer_tag);
 	hdr->statsn		= cpu_to_be32(conn->stat_sn);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 	hdr->r2tsn		= cpu_to_be32(r2t->r2t_sn);
 	hdr->data_offset	= cpu_to_be32(r2t->offset);
 	hdr->data_length	= cpu_to_be32(r2t->xfer_len);
@@ -3201,7 +3201,7 @@ void iscsit_build_rsp_pdu(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 
 	iscsit_increment_maxcmdsn(cmd, conn->sess);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 
 	pr_debug("Built SCSI Response, ITT: 0x%08x, StatSN: 0x%08x,"
 		" Response: 0x%02x, SAM Status: 0x%02x, CID: %hu\n",
@@ -3320,7 +3320,7 @@ iscsit_build_task_mgt_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 
 	iscsit_increment_maxcmdsn(cmd, conn->sess);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 
 	pr_debug("Built Task Management Response ITT: 0x%08x,"
 		" StatSN: 0x%08x, Response: 0x%02x, CID: %hu\n",
@@ -3575,7 +3575,7 @@ iscsit_build_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 	 */
 	cmd->maxcmdsn_inc = 0;
 	hdr->exp_cmdsn = cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn = cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn = cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 
 	pr_debug("Built Text Response: ITT: 0x%08x, TTT: 0x%08x, StatSN: 0x%08x,"
 		" Length: %u, CID: %hu F: %d C: %d\n", cmd->init_task_tag,
@@ -3653,7 +3653,7 @@ iscsit_build_reject(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 	cmd->stat_sn		= conn->stat_sn++;
 	hdr->statsn		= cpu_to_be32(cmd->stat_sn);
 	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->max_cmdsn		= cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));
 
 }
 EXPORT_SYMBOL(iscsit_build_reject);