[PATCH 33/40] scsi: libiscsi: add max/exp cmdsn lock

[Mike Christie <michael.christie@xxxxxxxxxx>]

This patch adds a lock for the max/exp_cmdsn handling. The next patch
will then cleanup the back_lock uses.

Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
 drivers/scsi/libiscsi.c     | 7 +++++--
 drivers/scsi/libiscsi_tcp.c | 2 --
 include/scsi/libiscsi.h     | 7 ++++---
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 33f8702faedd..dbff0ed10e1f 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -103,6 +103,7 @@ static void __iscsi_update_cmdsn(struct iscsi_session *session,
 	if (iscsi_sna_lt(max_cmdsn, exp_cmdsn - 1))
 		return;
 
+	spin_lock_bh(&session->back_cmdsn_lock);
 	if (exp_cmdsn != session->exp_cmdsn &&
 	    !iscsi_sna_lt(exp_cmdsn, session->exp_cmdsn))
 		session->exp_cmdsn = exp_cmdsn;
@@ -110,6 +111,7 @@ static void __iscsi_update_cmdsn(struct iscsi_session *session,
 	if (max_cmdsn != session->max_cmdsn &&
 	    !iscsi_sna_lt(max_cmdsn, session->max_cmdsn))
 		session->max_cmdsn = max_cmdsn;
+	spin_unlock_bh(&session->back_cmdsn_lock);
 }
 
 void iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
@@ -3067,6 +3069,7 @@ iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
 	spin_lock_init(&session->mgmt_lock);
 	spin_lock_init(&session->frwd_lock);
 	spin_lock_init(&session->back_lock);
+	spin_lock_init(&session->back_cmdsn_lock);
 
 	/* initialize mgmt task pool */
 	if (iscsi_pool_init(&session->mgmt_pool, ISCSI_MGMT_CMDS_MAX,
@@ -3470,9 +3473,9 @@ int iscsi_conn_bind(struct iscsi_cls_session *cls_session,
 	 * The target could have reduced it's window size between logins, so
 	 * we have to reset max/exp cmdsn so we can see the new values.
 	 */
-	spin_lock_bh(&session->back_lock);
+	spin_lock_bh(&session->back_cmdsn_lock);
 	session->max_cmdsn = session->exp_cmdsn = session->cmdsn + 1;
-	spin_unlock_bh(&session->back_lock);
+	spin_unlock_bh(&session->back_cmdsn_lock);
 	/*
 	 * Unblock xmitworker(), Login Phase will pass through.
 	 */
diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index b1399ff5ca9e..92e84a19b100 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -559,9 +559,7 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 	tcp_conn = conn->dd_data;
 	rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
 	/* fill-in new R2T associated with the task */
-	spin_lock(&session->back_lock);
 	iscsi_update_cmdsn(session, (struct iscsi_nopin *)rhdr);
-	spin_unlock(&session->back_lock);
 
 	if (tcp_conn->in.datalen) {
 		iscsi_conn_printk(KERN_ERR, conn,
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 6853b1dec0e3..3715b3d20890 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -296,10 +296,12 @@ struct iscsi_session {
 	struct mutex		eh_mutex;
 
 	/* iSCSI session-wide sequencing */
-	uint32_t		cmdsn;
+	/* Protects exp and max cmdsn */
+	spinlock_t		back_cmdsn_lock;
 	uint32_t		exp_cmdsn;
 	uint32_t		max_cmdsn;
 
+	uint32_t		cmdsn;
 	/* This tracks the reqs queued into the initiator */
 	uint32_t		queued_cmdsn;
 
@@ -356,8 +358,7 @@ struct iscsi_session {
 						 * cmdsn, suspend_bit,     *
 						 * leadconn, _stage,       *
 						 * tmf_state and queues    */
-	spinlock_t		back_lock;	/* protects cmdsn_exp and  *
-						 * cmdsn_max               */
+	spinlock_t		back_lock;
 	/*
 	 * frwd_lock must be held when transitioning states, but not needed
 	 * if just checking the state in the scsi-ml or iscsi callouts.
-- 
2.25.1