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>
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 05f1664..48f708b 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -656,6 +656,7 @@
struct iscsi_conn *conn;
struct se_session *se_sess;
ssize_t rb = 0;
+ u32 max_cmd_sn;
spin_lock_bh(&se_nacl->nacl_sess_lock);
se_sess = se_nacl->nacl_sess;
@@ -703,11 +704,12 @@
" Values]-----------------------\n");
rb += sprintf(page+rb, " CmdSN/WR : CmdSN/WC : ExpCmdSN"
" : MaxCmdSN : ITT : TTT\n");
+ max_cmd_sn = (u32) atomic_read(&sess->max_cmd_sn);
rb += sprintf(page+rb, " 0x%08x 0x%08x 0x%08x 0x%08x"
" 0x%08x 0x%08x\n",
sess->cmdsn_window,
- (sess->max_cmd_sn - sess->exp_cmd_sn) + 1,
- sess->exp_cmd_sn, sess->max_cmd_sn,
+ (max_cmd_sn - sess->exp_cmd_sn) + 1,
+ sess->exp_cmd_sn, max_cmd_sn,
sess->init_task_tag, sess->targ_xfer_tag);
rb += sprintf(page+rb, "----------------------[iSCSI"
" Connections]-------------------------\n");