target: Make locking in transport_deregister_session() IRQ safe

At least the tcm_qla2xxx fabric driver calls into transport_deregister_session()
while holding an IRQ-disabled spinlock, so the inner locking needs to
use spin_lock_irqsave() instead of spin_lock_bh().

This fixes warnings seen with tcm_qla2xxx like:

    WARNING: at kernel/softirq.c:159 local_bh_enable_ip+0x98/0xb0()
    Call Trace:
     [<ffffffff8104e65f>] warn_slowpath_common+0x7f/0xc0
     [<ffffffff8104e6ba>] warn_slowpath_null+0x1a/0x20
     [<ffffffff81055368>] local_bh_enable_ip+0x98/0xb0
     [<ffffffff814d5284>] _raw_spin_unlock_bh+0x14/0x20
     [<ffffffffa027b7f6>] transport_deregister_session+0x96/0x180 [target_core_mod]
     [<ffffffffa00f7731>] tcm_qla2xxx_free_session+0xd1/0x170 [tcm_qla2xxx]
     [<ffffffffa01b9173>] qla_tgt_sess_put+0xc3/0x140 [qla2xxx]
     [<ffffffffa01bf40f>] qla_tgt_stop_phase1+0x8f/0x2c0 [qla2xxx]
     [<ffffffffa00f735e>] tcm_qla2xxx_tpg_store_enable+0x6e/0xd0 [tcm_qla2xxx]
     [<ffffffffa026ca29>] target_fabric_tpg_attr_store+0x39/0x40 [target_core_mod]
     [<ffffffffa00a575d>] configfs_write_file+0xbd/0x120 [configfs]
     [<ffffffff811464a6>] vfs_write+0xc6/0x180
     [<ffffffff811467c1>] sys_write+0x51/0x90
     [<ffffffff814dd382>] system_call_fastpath+0x16/0x1b

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 9cc49d1b5b1f..8d0c58ea6316 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -389,17 +389,18 @@ void transport_deregister_session(struct se_session *se_sess)
 {
         struct se_portal_group *se_tpg = se_sess->se_tpg;
         struct se_node_acl *se_nacl;
+        unsigned long flags;
 
         if (!se_tpg) {
                 transport_free_session(se_sess);
                 return;
         }
 
-        spin_lock_bh(&se_tpg->session_lock);
+        spin_lock_irqsave(&se_tpg->session_lock, flags);
         list_del(&se_sess->sess_list);
         se_sess->se_tpg = NULL;
         se_sess->fabric_sess_ptr = NULL;
-        spin_unlock_bh(&se_tpg->session_lock);
+        spin_unlock_irqrestore(&se_tpg->session_lock, flags);
 
         /*
          * Determine if we need to do extra work for this initiator node's
@@ -407,22 +408,22 @@ void transport_deregister_session(struct se_session *se_sess)
          */
         se_nacl = se_sess->se_node_acl;
         if (se_nacl) {
-                spin_lock_bh(&se_tpg->acl_node_lock);
+                spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
                 if (se_nacl->dynamic_node_acl) {
                         if (!se_tpg->se_tpg_tfo->tpg_check_demo_mode_cache(
                                         se_tpg)) {
                                 list_del(&se_nacl->acl_list);
                                 se_tpg->num_node_acls--;
-                                spin_unlock_bh(&se_tpg->acl_node_lock);
+                                spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
 
                                 core_tpg_wait_for_nacl_pr_ref(se_nacl);
                                 core_free_device_list_for_node(se_nacl, se_tpg);
                                 se_tpg->se_tpg_tfo->tpg_release_fabric_acl(se_tpg,
                                                 se_nacl);
-                                spin_lock_bh(&se_tpg->acl_node_lock);
+                                spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
                         }
                 }
-                spin_unlock_bh(&se_tpg->acl_node_lock);
+                spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
         }
 
         transport_free_session(se_sess);