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.c b/drivers/target/iscsi/iscsi_target.c
index 986518c..e55f49c 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -2555,7 +2555,7 @@
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 @@
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_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_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 @@
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 @@
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_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 @@
*/
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 @@
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);