[PATCH-3.10.y 0/3] target: stable backports

[PATCH-3.10.y 0/3] target: stable backports

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

Hi Greg-KH,

Here are three target patches for v3.10.y stable, the first of which
did not originally include a stable CC, and the latter two did not
apply due to a minor context change.

The series has been cut against v3.10.108.  Please apply at your earliest
convenience.

Thank you,

--nab

Bart Van Assche (1):
  target/iscsi: Fix iSCSI task reassignment handling

Mikulas Patocka (1):
  iscsi-target: fix iscsit_del_np deadlock on unload

Nicholas Bellinger (1):
  iscsi-target: Fix iscsi_np reset hung task during parallel delete

 drivers/target/iscsi/iscsi_target.c       | 20 ++++++++------------
 drivers/target/iscsi/iscsi_target_core.h  |  1 +
 drivers/target/iscsi/iscsi_target_login.c | 25 ++++++++++++-------------
 include/target/target_core_base.h         |  1 +
 4 files changed, 22 insertions(+), 25 deletions(-)

-- 
1.8.5.3

[PATCH-3.10.y 1/3] target/iscsi: Fix iSCSI task reassignment handling

[Nicholas A. Bellinger]

From: Bart Van Assche <bart.vanassche@sandisk.com>

commit 59b6986dbfcdab96a971f9663221849de79a7556 upstream.

Allocate a task management request structure for all task management
requests, including task reassignment. This change avoids that the
se_tmr->response assignment dereferences an uninitialized se_tmr
pointer.

Reported-by: Moshe David <mdavid@infinidat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Moshe David <mdavid@infinidat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/iscsi/iscsi_target.c | 19 +++++++------------
 include/target/target_core_base.h   |  1 +
 2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index d74da95..e80ae5d 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1746,7 +1746,7 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	struct iscsi_tm *hdr;
 	int out_of_order_cmdsn = 0, ret;
 	bool sess_ref = false;
-	u8 function;
+	u8 function, tcm_function = TMR_UNKNOWN;
 
 	hdr			= (struct iscsi_tm *) buf;
 	hdr->flags &= ~ISCSI_FLAG_CMD_FINAL;
@@ -1792,10 +1792,6 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	 * LIO-Target $FABRIC_MOD
 	 */
 	if (function != ISCSI_TM_FUNC_TASK_REASSIGN) {
-
-		u8 tcm_function;
-		int ret;
-
 		transport_init_se_cmd(&cmd->se_cmd,
 				      &lio_target_fabric_configfs->tf_ops,
 				      conn->sess->se_sess, 0, DMA_NONE,
@@ -1832,15 +1828,14 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 			return iscsit_add_reject_cmd(cmd,
 				ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
 		}
-
-		ret = core_tmr_alloc_req(&cmd->se_cmd, cmd->tmr_req,
-					 tcm_function, GFP_KERNEL);
-		if (ret < 0)
-			return iscsit_add_reject_cmd(cmd,
+	}
+	ret = core_tmr_alloc_req(&cmd->se_cmd, cmd->tmr_req, tcm_function,
+				 GFP_KERNEL);
+	if (ret < 0)
+		return iscsit_add_reject_cmd(cmd,
 				ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
 
-		cmd->tmr_req->se_tmr_req = cmd->se_cmd.se_tmr_req;
-	}
+	cmd->tmr_req->se_tmr_req = cmd->se_cmd.se_tmr_req;
 
 	cmd->iscsi_opcode	= ISCSI_OP_SCSI_TMFUNC;
 	cmd->i_state		= ISTATE_SEND_TASKMGTRSP;
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 8e27143..0d54f60 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -214,6 +214,7 @@ enum tcm_tmreq_table {
 	TMR_LUN_RESET		= 5,
 	TMR_TARGET_WARM_RESET	= 6,
 	TMR_TARGET_COLD_RESET	= 7,
+	TMR_UNKNOWN		= 0xff,
 };
 
 /* fabric independent task management response values */
-- 
1.8.5.3

[PATCH-3.10.y 2/3] iscsi-target: fix iscsit_del_np deadlock on unload

[Nicholas A. Bellinger]

From: Mikulas Patocka <mpatocka@redhat.com>

commit 81a9c5e72bdf7109a65102ca61d8cbd722cf4021 upstream.

On uniprocessor preemptible kernel, target core deadlocks on unload. The
following events happen:
* iscsit_del_np is called
* it calls send_sig(SIGINT, np->np_thread, 1);
* the scheduler switches to the np_thread
* the np_thread is woken up, it sees that kthread_should_stop() returns
  false, so it doesn't terminate
* the np_thread clears signals with flush_signals(current); and goes back
  to sleep in iscsit_accept_np
* the scheduler switches back to iscsit_del_np
* iscsit_del_np calls kthread_stop(np->np_thread);
* the np_thread is waiting in iscsit_accept_np and it doesn't respond to
  kthread_stop

The deadlock could be resolved if the administrator sends SIGINT signal to
the np_thread with killall -INT iscsi_np

The reproducible deadlock was introduced in commit
db6077fd0b7dd41dc6ff18329cec979379071f87, but the thread-stopping code was
racy even before.

This patch fixes the problem. Using kthread_should_stop to stop the
np_thread is unreliable, so we test np_thread_state instead. If
np_thread_state equals ISCSI_NP_THREAD_SHUTDOWN, the thread exits.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/iscsi/iscsi_target_login.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 2c4db62..dd18956 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1168,7 +1168,7 @@ iscsit_conn_set_transport(struct iscsi_conn *conn, struct iscsit_transport *t)
 static int __iscsi_target_login_thread(struct iscsi_np *np)
 {
 	u8 *buffer, zero_tsih = 0;
-	int ret = 0, rc, stop;
+	int ret = 0, rc;
 	struct iscsi_conn *conn = NULL;
 	struct iscsi_login *login;
 	struct iscsi_portal_group *tpg = NULL;
@@ -1180,6 +1180,9 @@ static int __iscsi_target_login_thread(struct iscsi_np *np)
 	if (np->np_thread_state == ISCSI_NP_THREAD_RESET) {
 		np->np_thread_state = ISCSI_NP_THREAD_ACTIVE;
 		complete(&np->np_restart_comp);
+	} else if (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN) {
+		spin_unlock_bh(&np->np_thread_lock);
+		goto exit;
 	} else {
 		np->np_thread_state = ISCSI_NP_THREAD_ACTIVE;
 	}
@@ -1414,15 +1417,8 @@ old_sess_out:
 	}
 
 out:
-	stop = kthread_should_stop();
-	if (!stop && signal_pending(current)) {
-		spin_lock_bh(&np->np_thread_lock);
-		stop = (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN);
-		spin_unlock_bh(&np->np_thread_lock);
-	}
-	/* Wait for another socket.. */
-	if (!stop)
-		return 1;
+	return 1;
+
 exit:
 	iscsi_stop_login_thread_timer(np);
 	spin_lock_bh(&np->np_thread_lock);
@@ -1440,7 +1436,7 @@ int iscsi_target_login_thread(void *arg)
 
 	allow_signal(SIGINT);
 
-	while (!kthread_should_stop()) {
+	while (1) {
 		ret = __iscsi_target_login_thread(np);
 		/*
 		 * We break and exit here unless another sock_accept() call
-- 
1.8.5.3

[PATCH-3.10.y 3/3] iscsi-target: Fix iscsi_np reset hung task during parallel delete

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit 978d13d60c34818a41fc35962602bdfa5c03f214 upstream.

This patch fixes a bug associated with iscsit_reset_np_thread()
that can occur during parallel configfs rmdir of a single iscsi_np
used across multiple iscsi-target instances, that would result in
hung task(s) similar to below where configfs rmdir process context
was blocked indefinately waiting for iscsi_np->np_restart_comp
to finish:

[ 6726.112076] INFO: task dcp_proxy_node_:15550 blocked for more than 120 seconds.
[ 6726.119440]       Tainted: G        W  O     4.1.26-3321 #2
[ 6726.125045] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 6726.132927] dcp_proxy_node_ D ffff8803f202bc88     0 15550      1 0x00000000
[ 6726.140058]  ffff8803f202bc88 ffff88085c64d960 ffff88083b3b1ad0 ffff88087fffeb08
[ 6726.147593]  ffff8803f202c000 7fffffffffffffff ffff88083f459c28 ffff88083b3b1ad0
[ 6726.155132]  ffff88035373c100 ffff8803f202bca8 ffffffff8168ced2 ffff8803f202bcb8
[ 6726.162667] Call Trace:
[ 6726.165150]  [<ffffffff8168ced2>] schedule+0x32/0x80
[ 6726.170156]  [<ffffffff8168f5b4>] schedule_timeout+0x214/0x290
[ 6726.176030]  [<ffffffff810caef2>] ? __send_signal+0x52/0x4a0
[ 6726.181728]  [<ffffffff8168d7d6>] wait_for_completion+0x96/0x100
[ 6726.187774]  [<ffffffff810e7c80>] ? wake_up_state+0x10/0x10
[ 6726.193395]  [<ffffffffa035d6e2>] iscsit_reset_np_thread+0x62/0xe0 [iscsi_target_mod]
[ 6726.201278]  [<ffffffffa0355d86>] iscsit_tpg_disable_portal_group+0x96/0x190 [iscsi_target_mod]
[ 6726.210033]  [<ffffffffa0363f7f>] lio_target_tpg_store_enable+0x4f/0xc0 [iscsi_target_mod]
[ 6726.218351]  [<ffffffff81260c5a>] configfs_write_file+0xaa/0x110
[ 6726.224392]  [<ffffffff811ea364>] vfs_write+0xa4/0x1b0
[ 6726.229576]  [<ffffffff811eb111>] SyS_write+0x41/0xb0
[ 6726.234659]  [<ffffffff8169042e>] system_call_fastpath+0x12/0x71

It would happen because each iscsit_reset_np_thread() sets state
to ISCSI_NP_THREAD_RESET, sends SIGINT, and then blocks waiting
for completion on iscsi_np->np_restart_comp.

However, if iscsi_np was active processing a login request and
more than a single iscsit_reset_np_thread() caller to the same
iscsi_np was blocked on iscsi_np->np_restart_comp, iscsi_np
kthread process context in __iscsi_target_login_thread() would
flush pending signals and only perform a single completion of
np->np_restart_comp before going back to sleep within transport
specific iscsit_transport->iscsi_accept_np code.

To address this bug, add a iscsi_np->np_reset_count and update
__iscsi_target_login_thread() to keep completing np->np_restart_comp
until ->np_reset_count has reached zero.

Reported-by: Gary Guo <ghg@datera.io>
Tested-by: Gary Guo <ghg@datera.io>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/iscsi/iscsi_target.c       | 1 +
 drivers/target/iscsi/iscsi_target_core.h  | 1 +
 drivers/target/iscsi/iscsi_target_login.c | 7 +++++--
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index e80ae5d..6f95331 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -437,6 +437,7 @@ int iscsit_reset_np_thread(
 		return 0;
 	}
 	np->np_thread_state = ISCSI_NP_THREAD_RESET;
+	atomic_inc(&np->np_reset_count);
 
 	if (np->np_thread) {
 		spin_unlock_bh(&np->np_thread_lock);
diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index bf93e1c..bb71aad 100644
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -767,6 +767,7 @@ struct iscsi_np {
 	int			np_sock_type;
 	enum np_thread_state_table np_thread_state;
 	bool                    enabled;
+	atomic_t		np_reset_count;
 	enum iscsi_timer_flags_table np_login_timer_flags;
 	u32			np_exports;
 	enum np_flags_table	np_flags;
diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index dd18956..dce02ce 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1177,9 +1177,11 @@ static int __iscsi_target_login_thread(struct iscsi_np *np)
 	flush_signals(current);
 
 	spin_lock_bh(&np->np_thread_lock);
-	if (np->np_thread_state == ISCSI_NP_THREAD_RESET) {
+	if (atomic_dec_if_positive(&np->np_reset_count) >= 0) {
 		np->np_thread_state = ISCSI_NP_THREAD_ACTIVE;
+		spin_unlock_bh(&np->np_thread_lock);
 		complete(&np->np_restart_comp);
+		return 1;
 	} else if (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN) {
 		spin_unlock_bh(&np->np_thread_lock);
 		goto exit;
@@ -1212,7 +1214,8 @@ static int __iscsi_target_login_thread(struct iscsi_np *np)
 		goto exit;
 	} else if (rc < 0) {
 		spin_lock_bh(&np->np_thread_lock);
-		if (np->np_thread_state == ISCSI_NP_THREAD_RESET) {
+		if (atomic_dec_if_positive(&np->np_reset_count) >= 0) {
+			np->np_thread_state = ISCSI_NP_THREAD_ACTIVE;
 			spin_unlock_bh(&np->np_thread_lock);
 			complete(&np->np_restart_comp);
 			iscsit_put_transport(conn->conn_transport);
-- 
1.8.5.3

Re: [PATCH-3.10.y 0/3] target: stable backports

[Willy Tarreau]

Hi Nicholas,

On Thu, Nov 16, 2017 at 06:29:48AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Hi Greg-KH,
> 
> Here are three target patches for v3.10.y stable, the first of which
> did not originally include a stable CC, and the latter two did not
> apply due to a minor context change.
> 
> The series has been cut against v3.10.108.  Please apply at your earliest
> convenience.

That's kind of you but v3.10 reached end of life a week ago, it's not
maintained anymore.

Regards,
Willy