iscsi-target: Add login negotiation multi-plexing support

This patch adds support for login negotiation multi-plexing in
iscsi-target code.

This involves handling the first login request PDU + payload and
login response PDU + payload within __iscsi_target_login_thread()
process context, and then changing struct sock->sk_data_ready()
so that all subsequent exchanges are handled by workqueue process
context, to allow other incoming login requests to be received
in parallel by __iscsi_target_login_thread().

Upon login negotiation completion (or failure), ->sk_data_ready()
is replaced with the original kernel sockets handler saved in
iscsi_conn->orig_data_ready.

v3 changes:
  - Convert iscsi_target_sk_data_ready() lock access to
    write[lock,unlock]_bh()
  - Only clear LOGIN_FLAGS_READ_ACTIVE when iscsi_target_do_login()
    returns zero
  - Add LOGIN_FLAGS_READY + LOGIN_FLAGS_CLOSED bit checks to
    iscsi_target_sk_data_ready()
  - Make INIT_DELAYED_WORK() + iscsi_target_set_sock_callbacks() setup
    happen earlier by moving from iscsi_target_start_negotiation() into
    iscsi_target_locate_portal()
  - Set LOGIN_FLAGS_READY bit in iscsi_target_start_negotiation()
    after iscsi_target_do_login() returns zero.

v2 changes:
  - Add login_timer in iscsi_target_do_login_rx() to avoid
    possible endless sleep with MSG_WAITALL for traditional
    iscsi-target in certain network configurations.
  - Convert lprintk() -> pr_debug()
  - Remove forward declarations of iscsi_target_set_sock_callbacks(),
    iscsi_target_restore_sock_callbacks() and iscsi_target_sk_data_ready()
  - Make iscsi_target_set_sock_callbacks + iscsi_target_restore_sock_callbacks()
    static (Fengguang)
  - Make iscsi_target_do_login_rx() safe for iser-target w/o conn->sock

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/target/iscsi/iscsi_target_tpg.c b/drivers/target/iscsi/iscsi_target_tpg.c
index 4bf8913992a..e070ce2de60 100644
--- a/drivers/target/iscsi/iscsi_target_tpg.c
+++ b/drivers/target/iscsi/iscsi_target_tpg.c
@@ -129,7 +129,8 @@ void iscsit_release_discovery_tpg(void)
 
 struct iscsi_portal_group *iscsit_get_tpg_from_np(
 	struct iscsi_tiqn *tiqn,
-	struct iscsi_np *np)
+	struct iscsi_np *np,
+	struct iscsi_tpg_np **tpg_np_out)
 {
 	struct iscsi_portal_group *tpg = NULL;
 	struct iscsi_tpg_np *tpg_np;
@@ -147,6 +148,8 @@ struct iscsi_portal_group *iscsit_get_tpg_from_np(
 		spin_lock(&tpg->tpg_np_lock);
 		list_for_each_entry(tpg_np, &tpg->tpg_gnp_list, tpg_np_list) {
 			if (tpg_np->tpg_np == np) {
+				*tpg_np_out = tpg_np;
+				kref_get(&tpg_np->tpg_np_kref);
 				spin_unlock(&tpg->tpg_np_lock);
 				spin_unlock(&tiqn->tiqn_tpg_lock);
 				return tpg;
@@ -494,6 +497,8 @@ struct iscsi_tpg_np *iscsit_tpg_add_network_portal(
 	INIT_LIST_HEAD(&tpg_np->tpg_np_child_list);
 	INIT_LIST_HEAD(&tpg_np->tpg_np_parent_list);
 	spin_lock_init(&tpg_np->tpg_np_parent_lock);
+	init_completion(&tpg_np->tpg_np_comp);
+	kref_init(&tpg_np->tpg_np_kref);
 	tpg_np->tpg_np		= np;
 	tpg_np->tpg		= tpg;