diff options
| author | Roland Dreier <roland@purestorage.com> | 2015-07-24 00:53:32 +0300 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-08-03 09:11:52 +0300 |
| commit | 109e2381749c1cfd94a0d22b2b54142539024973 (patch) | |
| tree | 9695ecd3738a7bad43edcca4eb641339e7a30060 /drivers/target/iscsi/iscsi_target_nego.c | |
| parent | 24c7d6c7316c72301bf8ecfc1189fd476176fd75 (diff) | |
| download | linux-109e2381749c1cfd94a0d22b2b54142539024973.tar.xz | |
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>
Diffstat (limited to 'drivers/target/iscsi/iscsi_target_nego.c')
| -rw-r--r-- | drivers/target/iscsi/iscsi_target_nego.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c index 8c02fa34716f..74d041e815f4 100644 --- a/drivers/target/iscsi/iscsi_target_nego.c +++ b/drivers/target/iscsi/iscsi_target_nego.c @@ -340,7 +340,6 @@ static int iscsi_target_check_first_request( static int iscsi_target_do_tx_login_io(struct iscsi_conn *conn, struct iscsi_login *login) { u32 padding = 0; - struct iscsi_session *sess = conn->sess; struct iscsi_login_rsp *login_rsp; login_rsp = (struct iscsi_login_rsp *) login->rsp; @@ -352,7 +351,7 @@ static int iscsi_target_do_tx_login_io(struct iscsi_conn *conn, struct iscsi_log login_rsp->itt = login->init_task_tag; login_rsp->statsn = cpu_to_be32(conn->stat_sn++); login_rsp->exp_cmdsn = cpu_to_be32(conn->sess->exp_cmd_sn); - login_rsp->max_cmdsn = cpu_to_be32(conn->sess->max_cmd_sn); + login_rsp->max_cmdsn = cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn)); pr_debug("Sending Login Response, Flags: 0x%02x, ITT: 0x%08x," " ExpCmdSN; 0x%08x, MaxCmdSN: 0x%08x, StatSN: 0x%08x, Length:" @@ -367,10 +366,8 @@ static int iscsi_target_do_tx_login_io(struct iscsi_conn *conn, struct iscsi_log return -1; login->rsp_length = 0; - mutex_lock(&sess->cmdsn_mutex); - login_rsp->exp_cmdsn = cpu_to_be32(sess->exp_cmd_sn); - login_rsp->max_cmdsn = cpu_to_be32(sess->max_cmd_sn); - mutex_unlock(&sess->cmdsn_mutex); + login_rsp->exp_cmdsn = cpu_to_be32(login_rsp->exp_cmdsn); + login_rsp->max_cmdsn = cpu_to_be32(login_rsp->max_cmdsn); return 0; } |