iscsi-target: Fix iscsit_free_cmd() se_cmd->cmd_kref shutdown handling

With the introduction of target_get_sess_cmd() referencing counting for
ISCSI_OP_SCSI_CMD processing with iser-target, iscsit_free_cmd() usage
in traditional iscsi-target driver code now needs to be aware of the
active I/O shutdown case when a remaining se_cmd->cmd_kref reference may
exist after transport_generic_free_cmd() completes, requiring a final
target_put_sess_cmd() to release iscsi_cmd descriptor memory.

This patch changes iscsit_free_cmd() to invoke __iscsit_free_cmd() before
transport_generic_free_cmd() -> target_put_sess_cmd(), and also avoids
aquiring the per-connection queue locks for typical fast-path calls
during normal ISTATE_REMOVE operation.

Also update iscsit_free_cmd() usage throughout iscsi-target to
use the new 'bool shutdown' parameter.

This patch fixes a regression bug introduced during v3.10-rc1 in
commit 3e1c81a95, that was causing the following WARNING to appear:

[  257.235153] ------------[ cut here]------------
[  257.240314] WARNING: at kernel/softirq.c:160 local_bh_enable_ip+0x3c/0x86()
[  257.248089] Modules linked in: vhost_scsi ib_srpt ib_cm ib_sa ib_mad ib_core tcm_qla2xxx tcm_loop
	tcm_fc libfc iscsi_target_mod target_core_pscsi target_core_file
	target_core_iblock target_core_mod configfs ipv6 iscsi_tcp libiscsi_tcp
	libiscsi scsi_transport_iscsi loop acpi_cpufreq freq_table mperf
	kvm_intel kvm crc32c_intel button ehci_pci pcspkr joydev i2c_i801
	microcode ext3 jbd raid10 raid456 async_pq async_xor xor async_memcpy
	async_raid6_recov raid6_pq async_tx raid1 raid0 linear igb hwmon
	i2c_algo_bit i2c_core ptp ata_piix libata qla2xxx uhci_hcd ehci_hcd
	mlx4_core scsi_transport_fc scsi_tgt pps_core
[  257.308748] CPU: 1 PID: 3295 Comm: iscsi_ttx Not tainted 3.10.0-rc2+ #103
[  257.316329] Hardware name: Intel Corporation S5520HC/S5520HC, BIOS S5500.86B.01.00.0057.031020111721 03/10/2011
[  257.327597]  ffffffff814c24b7 ffff880458331b58 ffffffff8138eef2 ffff880458331b98
[  257.335892]  ffffffff8102c052 ffff880400000008 0000000000000000 ffff88085bdf0000
[  257.344191]  ffff88085bdf00d8 ffff88085bdf00e0 ffff88085bdf00f8 ffff880458331ba8
[  257.352488] Call Trace:
[  257.355223]  [<ffffffff8138eef2>] dump_stack+0x19/0x1f
[  257.360963]  [<ffffffff8102c052>] warn_slowpath_common+0x62/0x7b
[  257.367669]  [<ffffffff8102c080>] warn_slowpath_null+0x15/0x17
[  257.374181]  [<ffffffff81032345>] local_bh_enable_ip+0x3c/0x86
[  257.380697]  [<ffffffff813917fd>] _raw_spin_unlock_bh+0x10/0x12
[  257.387311]  [<ffffffffa029069c>] iscsit_free_r2ts_from_list+0x5e/0x67 [iscsi_target_mod]
[  257.396438]  [<ffffffffa02906c5>] iscsit_release_cmd+0x20/0x223 [iscsi_target_mod]
[  257.404893]  [<ffffffffa02977a4>] lio_release_cmd+0x3a/0x3e [iscsi_target_mod]
[  257.412964]  [<ffffffffa01d59a1>] target_release_cmd_kref+0x7a/0x7c [target_core_mod]
[  257.421712]  [<ffffffffa01d69bc>] target_put_sess_cmd+0x5f/0x7f [target_core_mod]
[  257.430071]  [<ffffffffa01d6d6d>] transport_release_cmd+0x59/0x6f [target_core_mod]
[  257.438625]  [<ffffffffa01d6eb4>] transport_put_cmd+0x131/0x140 [target_core_mod]
[  257.446985]  [<ffffffffa01d6192>] ? transport_wait_for_tasks+0xfa/0x1d5 [target_core_mod]
[  257.456121]  [<ffffffffa01d6f11>] transport_generic_free_cmd+0x4e/0x52 [target_core_mod]
[  257.465159]  [<ffffffff81050537>] ? __migrate_task+0x110/0x110
[  257.471674]  [<ffffffffa02904ba>] iscsit_free_cmd+0x46/0x55 [iscsi_target_mod]
[  257.479741]  [<ffffffffa0291edb>] iscsit_immediate_queue+0x301/0x353 [iscsi_target_mod]
[  257.488683]  [<ffffffffa0292f7e>] iscsi_target_tx_thread+0x1c6/0x2a8 [iscsi_target_mod]
[  257.497623]  [<ffffffff81047486>] ? wake_up_bit+0x25/0x25
[  257.503652]  [<ffffffffa0292db8>] ? iscsit_ack_from_expstatsn+0xd5/0xd5 [iscsi_target_mod]
[  257.512882]  [<ffffffff81046f89>] kthread+0xb0/0xb8
[  257.518329]  [<ffffffff81046ed9>] ? kthread_freezable_should_stop+0x60/0x60
[  257.526105]  [<ffffffff81396fec>] ret_from_fork+0x7c/0xb0
[  257.532133]  [<ffffffff81046ed9>] ? kthread_freezable_should_stop+0x60/0x60
[  257.539906] ---[ end trace 5520397d0f2e0800 ]---

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

4 files changed, 50 insertions, 26 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 262ef1f23b38..d7705e5824fb 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -651,7 +651,7 @@ static int iscsit_add_reject(
         cmd->buf_ptr = kmemdup(buf, ISCSI_HDR_LEN, GFP_KERNEL);
         if (!cmd->buf_ptr) {
                 pr_err("Unable to allocate memory for cmd->buf_ptr\n");
-                iscsit_release_cmd(cmd);
+                iscsit_free_cmd(cmd, false);
                 return -1;
         }
 
@@ -697,7 +697,7 @@ int iscsit_add_reject_from_cmd(
         cmd->buf_ptr = kmemdup(buf, ISCSI_HDR_LEN, GFP_KERNEL);
         if (!cmd->buf_ptr) {
                 pr_err("Unable to allocate memory for cmd->buf_ptr\n");
-                iscsit_release_cmd(cmd);
+                iscsit_free_cmd(cmd, false);
                 return -1;
         }
 
@@ -1743,7 +1743,7 @@ int iscsit_handle_nop_out(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
         return 0;
 out:
         if (cmd)
-                iscsit_release_cmd(cmd);
+                iscsit_free_cmd(cmd, false);
 ping_out:
         kfree(ping_data);
         return ret;
@@ -2251,7 +2251,7 @@ iscsit_handle_logout_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
         if (conn->conn_state != TARG_CONN_STATE_LOGGED_IN) {
                 pr_err("Received logout request on connection that"
                         " is not in logged in state, ignoring request.\n");
-                iscsit_release_cmd(cmd);
+                iscsit_free_cmd(cmd, false);
                 return 0;
         }
 
@@ -3665,7 +3665,7 @@ iscsit_immediate_queue(struct iscsi_conn *conn, struct iscsi_cmd *cmd, int state
                 list_del(&cmd->i_conn_node);
                 spin_unlock_bh(&conn->cmd_lock);
 
-                iscsit_free_cmd(cmd);
+                iscsit_free_cmd(cmd, false);
                 break;
         case ISTATE_SEND_NOPIN_WANT_RESPONSE:
                 iscsit_mod_nopin_response_timer(conn);
@@ -4122,7 +4122,7 @@ static void iscsit_release_commands_from_conn(struct iscsi_conn *conn)
 
                 iscsit_increment_maxcmdsn(cmd, sess);
 
-                iscsit_free_cmd(cmd);
+                iscsit_free_cmd(cmd, true);
 
                 spin_lock_bh(&conn->cmd_lock);
         }
diff --git a/drivers/target/iscsi/iscsi_target_erl2.c b/drivers/target/iscsi/iscsi_target_erl2.c
index ba6091bf93fc..45a5afd5ea13 100644
--- a/drivers/target/iscsi/iscsi_target_erl2.c
+++ b/drivers/target/iscsi/iscsi_target_erl2.c
@@ -143,7 +143,7 @@ void iscsit_free_connection_recovery_entires(struct iscsi_session *sess)
                         list_del(&cmd->i_conn_node);
                         cmd->conn = NULL;
                         spin_unlock(&cr->conn_recovery_cmd_lock);
-                        iscsit_free_cmd(cmd);
+                        iscsit_free_cmd(cmd, true);
                         spin_lock(&cr->conn_recovery_cmd_lock);
                 }
                 spin_unlock(&cr->conn_recovery_cmd_lock);
@@ -165,7 +165,7 @@ void iscsit_free_connection_recovery_entires(struct iscsi_session *sess)
                         list_del(&cmd->i_conn_node);
                         cmd->conn = NULL;
                         spin_unlock(&cr->conn_recovery_cmd_lock);
-                        iscsit_free_cmd(cmd);
+                        iscsit_free_cmd(cmd, true);
                         spin_lock(&cr->conn_recovery_cmd_lock);
                 }
                 spin_unlock(&cr->conn_recovery_cmd_lock);
@@ -248,7 +248,7 @@ void iscsit_discard_cr_cmds_by_expstatsn(
                 iscsit_remove_cmd_from_connection_recovery(cmd, sess);
 
                 spin_unlock(&cr->conn_recovery_cmd_lock);
-                iscsit_free_cmd(cmd);
+                iscsit_free_cmd(cmd, true);
                 spin_lock(&cr->conn_recovery_cmd_lock);
         }
         spin_unlock(&cr->conn_recovery_cmd_lock);
@@ -302,7 +302,7 @@ int iscsit_discard_unacknowledged_ooo_cmdsns_for_conn(struct iscsi_conn *conn)
                 list_del(&cmd->i_conn_node);
 
                 spin_unlock_bh(&conn->cmd_lock);
-                iscsit_free_cmd(cmd);
+                iscsit_free_cmd(cmd, true);
                 spin_lock_bh(&conn->cmd_lock);
         }
         spin_unlock_bh(&conn->cmd_lock);
@@ -355,7 +355,7 @@ int iscsit_prepare_cmds_for_realligance(struct iscsi_conn *conn)
 
                         list_del(&cmd->i_conn_node);
                         spin_unlock_bh(&conn->cmd_lock);
-                        iscsit_free_cmd(cmd);
+                        iscsit_free_cmd(cmd, true);
                         spin_lock_bh(&conn->cmd_lock);
                         continue;
                 }
@@ -375,7 +375,7 @@ int iscsit_prepare_cmds_for_realligance(struct iscsi_conn *conn)
                      iscsi_sna_gte(cmd->cmd_sn, conn->sess->exp_cmd_sn)) {
                         list_del(&cmd->i_conn_node);
                         spin_unlock_bh(&conn->cmd_lock);
-                        iscsit_free_cmd(cmd);
+                        iscsit_free_cmd(cmd, true);
                         spin_lock_bh(&conn->cmd_lock);
                         continue;
                 }
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 2cc6c9a3ffb8..08a3bacef0c5 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -676,40 +676,56 @@ void iscsit_free_queue_reqs_for_conn(struct iscsi_conn *conn)
 
 void iscsit_release_cmd(struct iscsi_cmd *cmd)
 {
-        struct iscsi_conn *conn = cmd->conn;
-
-        iscsit_free_r2ts_from_list(cmd);
-        iscsit_free_all_datain_reqs(cmd);
-
         kfree(cmd->buf_ptr);
         kfree(cmd->pdu_list);
         kfree(cmd->seq_list);
         kfree(cmd->tmr_req);
         kfree(cmd->iov_data);
 
-        if (conn) {
+        kmem_cache_free(lio_cmd_cache, cmd);
+}
+
+static void __iscsit_free_cmd(struct iscsi_cmd *cmd, bool scsi_cmd,
+                              bool check_queues)
+{
+        struct iscsi_conn *conn = cmd->conn;
+
+        if (scsi_cmd) {
+                if (cmd->data_direction == DMA_TO_DEVICE) {
+                        iscsit_stop_dataout_timer(cmd);
+                        iscsit_free_r2ts_from_list(cmd);
+                }
+                if (cmd->data_direction == DMA_FROM_DEVICE)
+                        iscsit_free_all_datain_reqs(cmd);
+        }
+
+        if (conn && check_queues) {
                 iscsit_remove_cmd_from_immediate_queue(cmd, conn);
                 iscsit_remove_cmd_from_response_queue(cmd, conn);
         }
-
-        kmem_cache_free(lio_cmd_cache, cmd);
 }
 
-void iscsit_free_cmd(struct iscsi_cmd *cmd)
+void iscsit_free_cmd(struct iscsi_cmd *cmd, bool shutdown)
 {
+        struct se_cmd *se_cmd = NULL;
+        int rc;
         /*
          * Determine if a struct se_cmd is associated with
          * this struct iscsi_cmd.
          */
         switch (cmd->iscsi_opcode) {
         case ISCSI_OP_SCSI_CMD:
-                if (cmd->data_direction == DMA_TO_DEVICE)
-                        iscsit_stop_dataout_timer(cmd);
+                se_cmd = &cmd->se_cmd;
+                __iscsit_free_cmd(cmd, true, shutdown);
                 /*
                  * Fallthrough
                  */
         case ISCSI_OP_SCSI_TMFUNC:
-                transport_generic_free_cmd(&cmd->se_cmd, 1);
+                rc = transport_generic_free_cmd(&cmd->se_cmd, 1);
+                if (!rc && shutdown && se_cmd && se_cmd->se_sess) {
+                        __iscsit_free_cmd(cmd, true, shutdown);
+                        target_put_sess_cmd(se_cmd->se_sess, se_cmd);
+                }
                 break;
         case ISCSI_OP_REJECT:
                 /*
@@ -718,11 +734,19 @@ void iscsit_free_cmd(struct iscsi_cmd *cmd)
                  * associated cmd->se_cmd needs to be released.
                  */
                 if (cmd->se_cmd.se_tfo != NULL) {
-                        transport_generic_free_cmd(&cmd->se_cmd, 1);
+                        se_cmd = &cmd->se_cmd;
+                        __iscsit_free_cmd(cmd, true, shutdown);
+
+                        rc = transport_generic_free_cmd(&cmd->se_cmd, 1);
+                        if (!rc && shutdown && se_cmd->se_sess) {
+                                __iscsit_free_cmd(cmd, true, shutdown);
+                                target_put_sess_cmd(se_cmd->se_sess, se_cmd);
+                        }
                         break;
                 }
                 /* Fall-through */
         default:
+                __iscsit_free_cmd(cmd, false, shutdown);
                 cmd->release_cmd(cmd);
                 break;
         }
diff --git a/drivers/target/iscsi/iscsi_target_util.h b/drivers/target/iscsi/iscsi_target_util.h
index 4f8e01a47081..a4422659d049 100644
--- a/drivers/target/iscsi/iscsi_target_util.h
+++ b/drivers/target/iscsi/iscsi_target_util.h
@@ -29,7 +29,7 @@ extern void iscsit_remove_cmd_from_tx_queues(struct iscsi_cmd *, struct iscsi_co
 extern bool iscsit_conn_all_queues_empty(struct iscsi_conn *);
 extern void iscsit_free_queue_reqs_for_conn(struct iscsi_conn *);
 extern void iscsit_release_cmd(struct iscsi_cmd *);
-extern void iscsit_free_cmd(struct iscsi_cmd *);
+extern void iscsit_free_cmd(struct iscsi_cmd *, bool);
 extern int iscsit_check_session_usage_count(struct iscsi_session *);
 extern void iscsit_dec_session_usage_count(struct iscsi_session *);
 extern void iscsit_inc_session_usage_count(struct iscsi_session *);