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Commit 109e2381 authored by Roland Dreier's avatar Roland Dreier Committed by Nicholas Bellinger
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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: default avatarRoland Dreier <roland@purestorage.com>
Signed-off-by: default avatarSpencer Baugh <sbaugh@catern.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 24c7d6c7

drivers/target/iscsi/iscsi_target.c

+9 −9
Original line number Original line Diff line number Diff line
@@ -2555,7 +2555,7 @@ static int iscsit_send_conn_drop_async_message( 
	cmd->stat_sn		= conn->stat_sn++;

	cmd->stat_sn		= conn->stat_sn++;

	hdr->statsn		= cpu_to_be32(cmd->stat_sn);

	hdr->statsn		= cpu_to_be32(cmd->stat_sn);

	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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->async_event	= ISCSI_ASYNC_MSG_DROPPING_CONNECTION;

	hdr->param1		= cpu_to_be16(cmd->logout_cid);

	hdr->param1		= cpu_to_be16(cmd->logout_cid);

	hdr->param2		= cpu_to_be16(conn->sess->sess_ops->DefaultTime2Wait);

	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->statsn		= cpu_to_be32(0xFFFFFFFF);





	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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->datasn		= cpu_to_be32(datain->data_sn);

	hdr->datasn		= cpu_to_be32(datain->data_sn);

	hdr->offset		= cpu_to_be32(datain->offset);

	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);

	iscsit_increment_maxcmdsn(cmd, conn->sess);

	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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));





	pr_debug("Built Logout Response ITT: 0x%08x StatSN:"

	pr_debug("Built Logout Response ITT: 0x%08x StatSN:"

		" 0x%08x Response: 0x%02x CID: %hu on CID: %hu\n",

		" 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);

		iscsit_increment_maxcmdsn(cmd, conn->sess);





	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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));





	pr_debug("Built NOPIN %s Response ITT: 0x%08x, TTT: 0x%08x,"

	pr_debug("Built NOPIN %s Response ITT: 0x%08x, TTT: 0x%08x,"

		" StatSN: 0x%08x, Length %u\n", (nopout_response) ?

		" 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->ttt		= cpu_to_be32(r2t->targ_xfer_tag);

	hdr->statsn		= cpu_to_be32(conn->stat_sn);

	hdr->statsn		= cpu_to_be32(conn->stat_sn);

	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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->r2tsn		= cpu_to_be32(r2t->r2t_sn);

	hdr->data_offset	= cpu_to_be32(r2t->offset);

	hdr->data_offset	= cpu_to_be32(r2t->offset);

	hdr->data_length	= cpu_to_be32(r2t->xfer_len);

	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);

	iscsit_increment_maxcmdsn(cmd, conn->sess);

	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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));





	pr_debug("Built SCSI Response, ITT: 0x%08x, StatSN: 0x%08x,"

	pr_debug("Built SCSI Response, ITT: 0x%08x, StatSN: 0x%08x,"

		" Response: 0x%02x, SAM Status: 0x%02x, CID: %hu\n",

		" 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);

	iscsit_increment_maxcmdsn(cmd, conn->sess);

	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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));





	pr_debug("Built Task Management Response ITT: 0x%08x,"

	pr_debug("Built Task Management Response ITT: 0x%08x,"

		" StatSN: 0x%08x, Response: 0x%02x, CID: %hu\n",

		" 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;

	cmd->maxcmdsn_inc = 0;

	hdr->exp_cmdsn = cpu_to_be32(conn->sess->exp_cmd_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));





	pr_debug("Built Text Response: ITT: 0x%08x, TTT: 0x%08x, StatSN: 0x%08x,"

	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,

		" 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++;

	cmd->stat_sn		= conn->stat_sn++;

	hdr->statsn		= cpu_to_be32(cmd->stat_sn);

	hdr->statsn		= cpu_to_be32(cmd->stat_sn);

	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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);

EXPORT_SYMBOL(iscsit_build_reject);

drivers/target/iscsi/iscsi_target_configfs.c

+4 −2
Original line number Original line Diff line number Diff line
@@ -656,6 +656,7 @@ static ssize_t lio_target_nacl_show_info( 
	struct iscsi_conn *conn;

	struct iscsi_conn *conn;

	struct se_session *se_sess;

	struct se_session *se_sess;

	ssize_t rb = 0;

	ssize_t rb = 0;

	u32 max_cmd_sn;





	spin_lock_bh(&se_nacl->nacl_sess_lock);

	spin_lock_bh(&se_nacl->nacl_sess_lock);

	se_sess = se_nacl->nacl_sess;

	se_sess = se_nacl->nacl_sess;
@@ -703,11 +704,12 @@ static ssize_t lio_target_nacl_show_info( 
				" Values]-----------------------\n");

				" Values]-----------------------\n");

		rb += sprintf(page+rb, "  CmdSN/WR  :  CmdSN/WC  :  ExpCmdSN"

		rb += sprintf(page+rb, "  CmdSN/WR  :  CmdSN/WC  :  ExpCmdSN"

				"  :  MaxCmdSN  :     ITT    :     TTT\n");

				"  :  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"

		rb += sprintf(page+rb, " 0x%08x   0x%08x   0x%08x   0x%08x"

				"   0x%08x   0x%08x\n",

				"   0x%08x   0x%08x\n",

			sess->cmdsn_window,

			sess->cmdsn_window,

			(sess->max_cmd_sn - sess->exp_cmd_sn) + 1,

			(max_cmd_sn - sess->exp_cmd_sn) + 1,

			sess->exp_cmd_sn, sess->max_cmd_sn,

			sess->exp_cmd_sn, max_cmd_sn,

			sess->init_task_tag, sess->targ_xfer_tag);

			sess->init_task_tag, sess->targ_xfer_tag);

		rb += sprintf(page+rb, "----------------------[iSCSI"

		rb += sprintf(page+rb, "----------------------[iSCSI"

				" Connections]-------------------------\n");

				" Connections]-------------------------\n");

drivers/target/iscsi/iscsi_target_device.c

+2 −5
Original line number Original line Diff line number Diff line
@@ -47,7 +47,7 @@ void iscsit_determine_maxcmdsn(struct iscsi_session *sess) 
	 * core_set_queue_depth_for_node().

	 * core_set_queue_depth_for_node().

	 */

	 */

	sess->cmdsn_window = se_nacl->queue_depth;

	sess->cmdsn_window = se_nacl->queue_depth;

	sess->max_cmd_sn = (sess->max_cmd_sn + se_nacl->queue_depth) - 1;

	atomic_set(&sess->max_cmd_sn, (u32) atomic_read(&sess->max_cmd_sn) + se_nacl->queue_depth - 1);

}

}





void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess)

void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess)
@@ -57,9 +57,6 @@ void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess 




	cmd->maxcmdsn_inc = 1;

	cmd->maxcmdsn_inc = 1;





	mutex_lock(&sess->cmdsn_mutex);

	pr_debug("Updated MaxCmdSN to 0x%08x\n", atomic_inc_return(&sess->max_cmd_sn));

	sess->max_cmd_sn += 1;

	pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn);

	mutex_unlock(&sess->cmdsn_mutex);

}

}

EXPORT_SYMBOL(iscsit_increment_maxcmdsn);
 
EXPORT_SYMBOL(iscsit_increment_maxcmdsn);

drivers/target/iscsi/iscsi_target_login.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -330,7 +330,7 @@ static int iscsi_login_zero_tsih_s1( 
	 * The FFP CmdSN window values will be allocated from the TPG's

	 * The FFP CmdSN window values will be allocated from the TPG's

	 * Initiator Node's ACL once the login has been successfully completed.

	 * Initiator Node's ACL once the login has been successfully completed.

	 */

	 */

	sess->max_cmd_sn	= be32_to_cpu(pdu->cmdsn);

	atomic_set(&sess->max_cmd_sn, be32_to_cpu(pdu->cmdsn));





	sess->sess_ops = kzalloc(sizeof(struct iscsi_sess_ops), GFP_KERNEL);

	sess->sess_ops = kzalloc(sizeof(struct iscsi_sess_ops), GFP_KERNEL);

	if (!sess->sess_ops) {

	if (!sess->sess_ops) {

drivers/target/iscsi/iscsi_target_nego.c

+3 −6
Original line number Original line Diff line number Diff line
@@ -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)

static int iscsi_target_do_tx_login_io(struct iscsi_conn *conn, struct iscsi_login *login)

{

{

	u32 padding = 0;

	u32 padding = 0;

	struct iscsi_session *sess = conn->sess;

	struct iscsi_login_rsp *login_rsp;

	struct iscsi_login_rsp *login_rsp;





	login_rsp = (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->itt			= login->init_task_tag;

	login_rsp->statsn		= cpu_to_be32(conn->stat_sn++);

	login_rsp->statsn		= cpu_to_be32(conn->stat_sn++);

	login_rsp->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_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,"

	pr_debug("Sending Login Response, Flags: 0x%02x, ITT: 0x%08x,"

		" ExpCmdSN; 0x%08x, MaxCmdSN: 0x%08x, StatSN: 0x%08x, Length:"

		" 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;

		return -1;





	login->rsp_length		= 0;

	login->rsp_length		= 0;

	mutex_lock(&sess->cmdsn_mutex);

	login_rsp->exp_cmdsn		= cpu_to_be32(login_rsp->exp_cmdsn);

	login_rsp->exp_cmdsn		= cpu_to_be32(sess->exp_cmd_sn);

	login_rsp->max_cmdsn		= cpu_to_be32(login_rsp->max_cmdsn);

	login_rsp->max_cmdsn		= cpu_to_be32(sess->max_cmd_sn);

	mutex_unlock(&sess->cmdsn_mutex);





	return 0;

	return 0;

}

}