target: Convert session_lock to irqsave

This patch converts the remaining struct se_portal_group->session_lock
usage to use irqsave+irqrestore to address the following warnings for
hardware target mode interrupt context usage.  This change generate
other warnings for current iscsi-target mode still using ->session_lock
with spin_lock_bh, which will need to be converted in a seperate patch.

[  492.480728] [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
[  492.488194] 3.0.0+ #23
[  492.490820] ------------------------------------------------------
[  492.497704] sh/7162 [HC0[0]:SC0[2]:HE0:SE0] is trying to acquire:
[  492.504493] (&(&se_tpg->session_lock)->rlock){+.....}, at: [<ffffffffa022364d>] transport_deregister_session+0x2d/0x163 [target_core_mod]
  492.518390]
[  492.518390] and this task is already holding:
[  492.524897] (&(&ha->hardware_lock)->rlock){-.-...}, at: [<ffffffffa00b9146>] qla_tgt_stop_phase1+0x5e/0x27e [qla2xxx]
[  492.536856] which would create a new lock dependency:
[  492.542481] (&(&ha->hardware_lock)->rlock){-.-...} -> (&(&se_tpg->session_lock)->rlock){+.....}
[  492.552321]
[  492.552321] but this new dependency connects a HARDIRQ-irq-safe lock:
[  492.561149] (&(&ha->hardware_lock)->rlock){-.-...}
[  492.566400] ... which became HARDIRQ-irq-safe at:
[  492.571841]   [<ffffffff81064720>] __lock_acquire+0x68f/0x921
[  492.578247]   [<ffffffff81064eff>] lock_acquire+0xe0/0x10d
[  492.584367]   [<ffffffff813a74c6>] _raw_spin_lock_irqsave+0x44/0x56
[  492.591358]   [<ffffffffa009b1be>] qla24xx_msix_default+0x5c/0x2aa [qla2xxx]
[  492.599227]   [<ffffffff81088582>] handle_irq_event_percpu+0x5a/0x197
[  492.606413]   [<ffffffff810886fb>] handle_irq_event+0x3c/0x5c
[  492.612822]   [<ffffffff8108a6dc>] handle_edge_irq+0xcc/0xf1
[  492.619138]   [<ffffffff810039b9>] handle_irq+0x83/0x8e
[  492.624971]   [<ffffffff8100333e>] do_IRQ+0x48/0xaf
[  492.630413]   [<ffffffff813a7cd3>] ret_from_intr+0x0/0x1a
[  492.636437]   [<ffffffff81001dc1>] cpu_idle+0x5b/0x8d
[  492.642073]   [<ffffffff81392709>] rest_init+0xad/0xb4
[  492.647809]   [<ffffffff81a1cbbc>] start_kernel+0x366/0x371
[  492.654030]   [<ffffffff81a1c2b1>] x86_64_start_reservations+0xb8/0xbc
[  492.661311]   [<ffffffff81a1c3b6>] x86_64_start_kernel+0x101/0x110
[  492.668204]
[  492.668205] to a HARDIRQ-irq-unsafe lock:
[  492.674324] (&(&se_tpg->session_lock)->rlock){+.....}
[  492.679862] ... which became HARDIRQ-irq-unsafe at:
[  492.685497] ...  [<ffffffff8106479a>] __lock_acquire+0x709/0x921
[  492.692209]   [<ffffffff81064eff>] lock_acquire+0xe0/0x10d
[  492.698330]   [<ffffffff813a75ed>] _raw_spin_lock_bh+0x31/0x40
[  492.704836]   [<ffffffffa021c208>] core_tpg_del_initiator_node_acl+0x89/0x336 [target_core_mod]
[  492.714546]   [<ffffffffa02fb075>] tcm_qla2xxx_drop_nodeacl+0x20/0x2d [tcm_qla2xxx]
[  492.723087]   [<ffffffffa02108d9>] target_fabric_nacl_base_release+0x22/0x24 [target_core_mod]
[  492.732698]   [<ffffffffa01661c8>] config_item_release+0x7d/0xa3 [configfs]
[  492.740465]   [<ffffffff811d48fe>] kref_put+0x43/0x4d
[  492.746101]   [<ffffffffa0166149>] config_item_put+0x19/0x1b [configfs]
[  492.753481]   [<ffffffffa0164987>] configfs_rmdir+0x1eb/0x258 [configfs]
[  492.760957]   [<ffffffff810ecc54>] vfs_rmdir+0x79/0xd0
[  492.766690]   [<ffffffff810eec4a>] do_rmdir+0xc2/0x111
[  492.772423]   [<ffffffff810eecd0>] sys_rmdir+0x11/0x13
[  492.778156]   [<ffffffff813ae4d2>] system_call_fastpath+0x16/0x1b
[  492.784953]
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_tpg.c

@@ -449,6 +449,7 @@ int core_tpg_del_initiator_node_acl(
 	int force)
 {
 	struct se_session *sess, *sess_tmp;
+	unsigned long flags;
 	int dynamic_acl = 0;
 
 	spin_lock_irq(&tpg->acl_node_lock);
@@ -460,7 +461,7 @@ int core_tpg_del_initiator_node_acl(
 	tpg->num_node_acls--;
 	spin_unlock_irq(&tpg->acl_node_lock);
 
-	spin_lock_bh(&tpg->session_lock);
+	spin_lock_irqsave(&tpg->session_lock, flags);
 	list_for_each_entry_safe(sess, sess_tmp,
 				&tpg->tpg_sess_list, sess_list) {
 		if (sess->se_node_acl != acl)
@@ -471,16 +472,16 @@ int core_tpg_del_initiator_node_acl(
 		if (!tpg->se_tpg_tfo->shutdown_session(sess))
 			continue;
 
-		spin_unlock_bh(&tpg->session_lock);
+		spin_unlock_irqrestore(&tpg->session_lock, flags);
 		/*
 		 * If the $FABRIC_MOD session for the Initiator Node ACL exists,
 		 * forcefully shutdown the $FABRIC_MOD session/nexus.
 		 */
 		tpg->se_tpg_tfo->close_session(sess);
 
-		spin_lock_bh(&tpg->session_lock);
+		spin_lock_irqsave(&tpg->session_lock, flags);
 	}
-	spin_unlock_bh(&tpg->session_lock);
+	spin_unlock_irqrestore(&tpg->session_lock, flags);
 
 	core_tpg_wait_for_nacl_pr_ref(acl);
 	core_clear_initiator_node_from_tpg(acl, tpg);
@@ -507,6 +508,7 @@ int core_tpg_set_initiator_node_queue_depth(
 {
 	struct se_session *sess, *init_sess = NULL;
 	struct se_node_acl *acl;
+	unsigned long flags;
 	int dynamic_acl = 0;
 
 	spin_lock_irq(&tpg->acl_node_lock);
@@ -525,7 +527,7 @@ int core_tpg_set_initiator_node_queue_depth(
 	}
 	spin_unlock_irq(&tpg->acl_node_lock);
 
-	spin_lock_bh(&tpg->session_lock);
+	spin_lock_irqsave(&tpg->session_lock, flags);
 	list_for_each_entry(sess, &tpg->tpg_sess_list, sess_list) {
 		if (sess->se_node_acl != acl)
 			continue;
@@ -537,7 +539,7 @@ int core_tpg_set_initiator_node_queue_depth(
 				" depth and force session reinstatement"
 				" use the \"force=1\" parameter.\n",
 				tpg->se_tpg_tfo->get_fabric_name(), initiatorname);
-			spin_unlock_bh(&tpg->session_lock);
+			spin_unlock_irqrestore(&tpg->session_lock, flags);
 
 			spin_lock_irq(&tpg->acl_node_lock);
 			if (dynamic_acl)
@@ -567,7 +569,7 @@ int core_tpg_set_initiator_node_queue_depth(
 	acl->queue_depth = queue_depth;
 
 	if (core_set_queue_depth_for_node(tpg, acl) < 0) {
-		spin_unlock_bh(&tpg->session_lock);
+		spin_unlock_irqrestore(&tpg->session_lock, flags);
 		/*
 		 * Force session reinstatement if
 		 * core_set_queue_depth_for_node() failed, because we assume
@@ -583,7 +585,7 @@ int core_tpg_set_initiator_node_queue_depth(
 		spin_unlock_irq(&tpg->acl_node_lock);
 		return -EINVAL;
 	}
-	spin_unlock_bh(&tpg->session_lock);
+	spin_unlock_irqrestore(&tpg->session_lock, flags);
 	/*
 	 * If the $FABRIC_MOD session for the Initiator Node ACL exists,
 	 * forcefully shutdown the $FABRIC_MOD session/nexus.

drivers/target/target_core_transport.c

@@ -252,7 +252,7 @@ struct se_session *transport_init_session(void)
 EXPORT_SYMBOL(transport_init_session);
 
 /*
- * Called with spin_lock_bh(&struct se_portal_group->session_lock called.
+ * Called with spin_lock_irqsave(&struct se_portal_group->session_lock called.
  */
 void __transport_register_session(
 	struct se_portal_group *se_tpg,
@@ -305,9 +305,11 @@ void transport_register_session(
 	struct se_session *se_sess,
 	void *fabric_sess_ptr)
 {
-	spin_lock_bh(&se_tpg->session_lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&se_tpg->session_lock, flags);
 	__transport_register_session(se_tpg, se_nacl, se_sess, fabric_sess_ptr);
-	spin_unlock_bh(&se_tpg->session_lock);
+	spin_unlock_irqrestore(&se_tpg->session_lock, flags);
 }
 EXPORT_SYMBOL(transport_register_session);