diff options
| author | Roland Dreier <roland@purestorage.com> | 2015-07-23 14:53:32 -0700 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-08-02 23:11:52 -0700 |
| commit | 109e2381749c1cfd94a0d22b2b54142539024973 (patch) | |
| tree | 9695ecd3738a7bad43edcca4eb641339e7a30060 /drivers/target/iscsi/iscsi_target_util.c | |
| parent | 24c7d6c7316c72301bf8ecfc1189fd476176fd75 (diff) | |
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_util.c')
| -rw-r--r-- | drivers/target/iscsi/iscsi_target_util.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c index a2bff0702eb2..7df4fac69f39 100644 --- a/drivers/target/iscsi/iscsi_target_util.c +++ b/drivers/target/iscsi/iscsi_target_util.c @@ -233,6 +233,7 @@ struct iscsi_r2t *iscsit_get_holder_for_r2tsn( static inline int iscsit_check_received_cmdsn(struct iscsi_session *sess, u32 cmdsn) { + u32 max_cmdsn; int ret; /* @@ -241,10 +242,10 @@ static inline int iscsit_check_received_cmdsn(struct iscsi_session *sess, u32 cm * or order CmdSNs due to multiple connection sessions and/or * CRC failures. */ - if (iscsi_sna_gt(cmdsn, sess->max_cmd_sn)) { + max_cmdsn = atomic_read(&sess->max_cmd_sn); + if (iscsi_sna_gt(cmdsn, max_cmdsn)) { pr_err("Received CmdSN: 0x%08x is greater than" - " MaxCmdSN: 0x%08x, ignoring.\n", cmdsn, - sess->max_cmd_sn); + " MaxCmdSN: 0x%08x, ignoring.\n", cmdsn, max_cmdsn); ret = CMDSN_MAXCMDSN_OVERRUN; } else if (cmdsn == sess->exp_cmd_sn) { |